Neotropical Anacardiaceae (cashew family)

Anacardiaceae is an ecologically and economically important plant family of about 200 species in 32 genera in the Neotropics. The family is particularly diverse in leaf architecture and fruit morphology, making it a model family to study the evolution of structural diversity as it correlates with lineage diversification. This fruit diversity is the primary reason 11 of the Neotropical genera are monotypic and that so many genera are recognized in the Anacardiaceae. The economic value of the family is driven by the global markets for cashews, mangoes, and pistachios, but there is great potential value in its medicinal properties. At least 10 Neotropical genera cause contact dermatitis, which is a rich area for research in the family. Here presented is a review of the systematics and structural diversity of the family. Particular attention is given to the morphology, economic botany, paleobotany, ecology, and taxonomy of native and naturalized genera. Keys to Neotropical Anacardiaceae subfamilies and genera are provided along with descriptions of native genera.


Introduction
Accounting for nearly 200 species and 32 genera in the Neotropics (ca. 800 species and more than 80 genera globally), the Anacardiaceae is an ecologically and economically important plant family. The family includes valuable global fruit and seed crops such as cashew (Anacardium occidentale L.), mango (Mangifera indica L.), pink peppercorn (Schinus areira L. and Schinus terebinthifolia Raddi), and pistachio (Pistacia vera L.), and Neotropical fruit crops such as jocote/ciruela/siriguela (Spondias purpurea L.), cajá/jobo (Spondias mombin L.), umbu (Spondias tuberosa Arruda), and jobo dos Indios/pomme cythére (Spondias dulcis Parkinson). Members of the family are also used for medicine, timber, industrial applications, and much more. Anacardiaceae are notorious for causing contact dermatitis, but many of the toxic species are also useful.
The family is distributed from temperate North America, Asia, and Europe to temperate South America, Africa, and Australia. However, the greatest diversity of lineages occurs in the world's tropical areas and the center of diversity for the family is Southeast Asia. Approximately one quarter of all Anacardiaceae species are native to the Neotropics, with Schinus being the largest genus with 42 species. Eleven of the 32 Neotropical genera are monotypic, which is primarily a reflection of the great fruit diversity in the family, and seven genera are disjunct between the Old and New Worlds, presenting excellent opportunities for testing biogeographic hypotheses.
Here, we present an overview of the Neotropical Anacardiaceae. Synopses are provided for evolution, taxonomy, morphology, anatomy, ecology, paleobotany, phytochemistry, and economic and ethnobotany. John Mitchell and Susan Pell edited the entire manuscript, while the numerous authors have each contributed their Anacardiaceae expertise in individual sections and provided key insights across the manuscript. Some of the text presented here is adapted and updated from the two lead authors' Anacardiaceae treatment for the Families and Genera of Vascular Plants series ).

Phylogenetic and taxonomic overview
The family Anacardiaceae has a rich history of evolutionary and taxonomic study beginning before Linnaeus and extending to the present day. The family was first recognized by Lindley in 1830 upon his subdivision of Terebinthaceae, a large family described by Jussieu (1789) that included genera from taxa now classified in Anacardiaceae, Burseraceae, Simaroubaceae, Rutaceae, Connaraceae, Euphorbiaceae, and Averrhoaceae. The taxonomic history of Anacardiaceae is complex, with Anacardiaceous taxa historically placed in other families including Blepharocaryaceae, Comocladiaceae, Julianiaceae, Pistaciaceae, Podoaceae, Rhoaceae, Schinaceae, and Spondiadaceae ). Bentham and Hooker (1862) were the first to propose generic groupings within Anacardiaceae, dividing the family into two tribes-Anacardieae and Spondieae-based on the number of ovary locules and ovule insertion on the placenta. These characters were then used in Marchand's (1869) classification in which he recognized nine tribes (Spondieae, Thyrsodieae, Tapirieae, Semecarpeae, Astronieae, Rhoideae, Pistacieae, Mangifereae, and Buchananieae). This tribal classification was modified by Engler in 1876 in his treatment of Brazilian Anacardiaceae, then later in 1881, 1883 and finally in 1892 where he recognized five tribes: Mangifereae (= Anacardieae), Rhoideae (= Rhoeae), Semecarpeae, and Spondieae (= Spondiadeae), and Dobineeae (= Dobineae). Like Bentham and Hooker, Engler used the number of ovary locules and ovule insertion on the placenta to circumscribe these tribes, in addition to other characters including the phyllotaxy, leaf morphology, presence of a perianth in the female flower, number of staminal whorls, stylar insertion on the ovary, carpel number, and embryo morphology.
Engler's tribal classification was generally accepted in subsequent treatments of Anacardiaceae (see additional references) and was most recently revised by Mitchell and Mori (1987). However, based on pericarp structure, wood anatomy, and biflavonoid data, Quinn (1990, 1991) suggested that Engler's tribal classification was artificial, and that the small families previously considered to be sister to Anacardiaceae-Julianiaceae and Blepharocaryaceaeshould be sunk into Anacardiaceae. They tentatively identified two major groups of genera, each divided into two subgroups. The genera previously included in Julianiaceae (Amphipterygium and Orthopterygium) and Blepharocaryaceae (Blepharocarya), as well as Engler's tribes Anacardieae, Dobineae, Rhoeae, and Semecarpeae, were placed in Group A, with the exception of Androtium, Buchanania, Campnosperma, and Pentaspadon. These four genera and all Spondiadeae were placed in Group B. Two genera-Faguetia and Pseudoprotorhus (= Filicium, Sapindaceae)-were not assignable to either group in this treatment. Terrazas (1994) used rbcL sequences and morphological and wood anatomical data to study the phylogeny of the family. Her combined rbcL-morphology phylogeny elucidated a monophyletic Anacardiaceae of two major clades. One clade (A1) contains taxa from tribes Anacardieae, Dobineae, Rhoeae, and Semecarpeae and is supported by two synapomorphies: unicellular stalked leaf glands and having both septate and nonseptate fibers in the wood. The other clade (A2) contains Spondiadeae plus Pentaspadon and is supported by the synapomorphy of leaves with multicellular stalked glands. Terrazas (1994) proposed, but never formally named, these two clades as subfamilies Anacardioideae and Spondioideae, respectively. Pell (2004) found support for these subfamilies based on phylogenetic analysis of three plastid genes and formally circumscribed and described them. Each of Engler's tribes (sensu Mitchell and Mori 1987) was assigned to a subfamily, with Anacardieae, Dobineae, Rhoeae, and Semecarpeae grouped into Anacardioideae, and Spondiadeae ranked as Spondioideae; however, it was noted that some tribes were polyphyletic in some gene trees. This subfamilial classification was altered in Mitchell et al. (2006; see also Pell et al. 2011), where Buchanania was recognized as a member of Spondioideae on the basis of unpublished molecular data, in line with the morphological groupings of Quinn (1990, 1991). It was also noted in Pell et al. (2011) that the unpublished molecular analysis retrieved Spondioideae as polyphyletic, although without complete resolution of Anacardiaceae relationships the two-subfamily classification system was maintained in the treatment.
The placement of Buchanania in Spondioideae and polyphyly of Spondioideae was later supported in the molecular analysis of one nuclear and three chloroplast markers by Weeks et al (2014). This study also challenged the tribal classification of Anacardiaceae, and as in previous studies, retrieved only Dobineae and Semecarpeae as monophyletic. Recent, target sequence capture data of 353 nuclear genes and 83% of Anacardiaceae genera generally support the subfamilial classification of Pell et al. (2011), retrieving Spondioideae as monophyletic (Joyce 2021, Joyce et al. unpublished). However, these data suggest Anacardioideae is polyphyletic, retrieving Campnosperma as an early diverging lineage in Spondioideae in support of the findings of Quinn (1990, 1991) and Weeks et al. (2014). Like the molecular analyses of Pell (2004) and Weeks et al. (2014), this recent molecular data indicate that all tribes are polyphyletic with the exception of Dobineae (Campylopetalum and Dobinea) and Semecarpeae (including samples of Semecarpus, Drimycarpus, Nothopegia, and Melanochyla, but missing Holigarna), suggesting that the tribal classification of the family is in need of revision in order to be reflective of resolved clades (Joyce 2021;Joyce et al. unpublished). At the genus level, the phylogenetic data (Joyce 2021;Joyce et al. unpublished) and morphological analyses (Herrera et al. 2018) also suggest that Cyrtocarpa and Poupartia are polyphyletic and confirm the findings of previous authors that Rhus is polyphyletic and in urgent need of taxonomic revision (Yi et al. 2007).
Androtium, Haematostaphis, Haplospondias, Holigarna, Koordersiodendron, and Solenocarpus have never been included in molecular studies, and their relationships within Anacardiaceae as defined by morphology are yet to be corroborated with molecular data. The classification of Pentaspadon remains controversial because morphological studies have placed the genus contrastingly in Anacardioideae (Mitchell and Mori 1987) and Spondioideae (Wannan and Quinn 1991), and the molecular study of Weeks et al. (2014) retrieved it as sister to all Anacardiaceae. Further study of Pentaspadon and inclusion in a next-generation molecular study is needed to elucidate the placement of this genus.
At higher taxonomic levels, Anacardiaceae is most closely related to Burseraceae, sharing vertical intercellular secretory canals in the primary and secondary phloem and the ability to synthesize biflavonyls (Wannan et al. 1985;Quinn 1990, 1991;Terrazas 1994). Additionally, members of these families are often resinous and possess ovules whose funicles typically have a dorsal bend projecting toward the base of the style, referred to as a ponticulus Bachelier and Endress 2009;Pell et al. 2011). The close relationship of Anacardiaceae and Burseraceae has been supported by numerous morphological, anatomical, biochemical, and molecular studies (Gadek et al. 1996;Pell 2004;Bachelier and Endress 2009;Weeks et al. 2014;APG 2016;Joyce 2021, Joyce et al. unpublished). Morphological similarities between the gynoecia of some Spondioideae and Beiselia, which is sister to all other Burseraceae, support a close relationship between the two families and support their affinities with Kirkiaceae Endress 2007, 2009). However, Anacardiaceae can be distinguished from Burseraceae by the presence of a single apotropous (syntropous) ovule per locule instead of two epitropous (antitropous) ovules per locule as in Burseraceae. Some Anacardiaceae members can also be separated from most Burseraceae members by the presence of 5-deoxyflavonoids and contact dermatitis-causing compounds, indehiscent fruits, and a lack of stipules, pseudostipules, and terminal pulvinuli subtending the leaflet laminae . Historically, Anacardiaceae has variously been classified within the orders of Burserales, Rutales, Sapindales, or Terebinthinae; molecular studies support its placement within Sapindales (Gadek et al. 1996;APG 2016;Muellner et al. 2016;Joyce 2021).
Leaf architecture within Anacardiaceae is extremely diverse (Martínez-Millán and Cevallos-Ferriz 2005;Ellis et al. 2009), and the terminology used here to describe it is based on the Manual of Leaf Architecture (Ellis et al. 2009). Primary leaf venation is pinnate, and secondary venation is most commonly eucamptodromous, brochidodromous (usually festooned), craspedodromous, semi-craspedodromous, or cladodromous (when present in Sapindales, the latter is usually diagnostic of Anacardiaceae; e.g., Astronium, Comocladia, Cotinus, Pseudosmodingium, Rhus, Schinus). Some authors have noted the need to reevaluate cladodromous venation to further distinguish it into different categories (Martínez-Millán and Cevallos-Feriz 2005). A relatively rare but quite distinctive character is craspedodromous with an intramarginal secondary vein, which occurs in Attilaea and Spondias, and has recently been reported in Lithrea (Mercado et al. 2014). Marginal secondary veins are rarely present (e.g., Lithrea, Spondias radlkoferi Donn. Sm.). Venation in Spondias exemplifies the utility of leaf architecture for distinguishing species in the family (Mitchell and Daly 2015).
Trichomes in Neotropical Anacardiaceae may be simple, lepidote, or stellate; unicellular or multicellular; sessile or stalked; and glandular or non-glandular. Two types of trichomes were described in detail for Rhus subgenus Rhus: acicular and bulbous gland type (Hardin and Phillips 1985). Stellate trichomes occur in some taxa (e.g., Campnosperma, Pseudosmodingium) (Aguilar-Ortigoza and Sosa 2004a). Lepidote scales are rarely present in the family, but are characteristic of Campnosperma and Tapirira lepidota Aguilar & Hammel.
Leaf anatomy in Anacardiaceae has been researched by many authors, including Metcalfe and Chalk (1950), who provided an overview, and Wilkinson (1971) who studied epidermal features. Many others covered specific genera or habitats (Paula and Alves 1973;Silva 1973;Gibson 1981;Muñoz 1990). Hairy tuft domatia (e.g., Mauria, Spondias, Toxicodendron) or marsupiform domatia (e.g., Anacardium, Schinus) are sometimes present in the secondary vein axils abaxially or associated with the petiole or the base of the leaflet (Mitchell and Daly 2015).
Leaf extrafloral nectaries have also been documented in the secondary vein axils of the leaves and on the adaxial surface of the petiole where it meets the blade of Anacardium humile and A. occidentale. They are composed of several multicellular and multiseriate nectariferous trichomes that produce glucose-for this reason, they have sometimes been interpreted as extrafloral nectaries rather than as domatia (e.g., Lacchia et al. 2016).

Reproductive morphology -Inflorescences and flowers.
Inflorescences of Anacardiaceae can be terminal or axillary and tend to be clustered with the leaves toward the tips of the branches. They are often branched and range from panicles to thyrsoids or thyrses and racemes, ending in lax to compact cymose units sensu Endress (2010), or are spicate. In two dioecious Neotropical genera of Anacardioideae, female inflorescences can also develop into a cupular involucre formed by the subtending bracts of the (female) flowers in Amphipterygium and Orthopterygium Quinn 1991, 1992;Bachelier and Endress 2007;Herrera and Bachelier 2016). Extrafloral nectaries have also been reported at the junctions of the panicle branches in Anacardium occidentale.
Flowers can be few to numerous, or rarely solitary in a few Schinus species (Barkley 1957;Silva-Luz et al. 2019), and are relatively small (< 1 cm in diameter in the Neotropics). They are usually bisexual to functionally or morphologically unisexual, with an isomerous pentamerous perianth and androecium, and a fleshy annular or lobed intrastaminal disk (lobed extrastaminal disk in Mangifera). Both the perianth and/or disk can be absent or severely reduced in wind-pollinated taxa (e.g., Amphipterygium, Orthopterygium, Pistacia), which are found only in Anacardioideae that primarily occur in at least seasonally dry habitats (see below for more information on the disk). The gynoecium is syncarpous (or rarely monomerous) with a superior ovary and as many carpels as there are styles and stigmas or stigmatic lobes (Wannan and Quinn 1991;Endress 2007, 2009;Tölke et al. 2021a). The flowers in Neotropical Spondioideae are usually obdiplostemonous with as many carpels as there are petals facing them and usually have an ovary with as many locules as styles and stigmas (Wannan and Quinn 1991;Bachelier and Endress 2009;Tölke et al. 2021a). In contrast, in Anacardioideae the androecium is usually haplostemonous (e.g., Astronium, Comocladia, Cotinus, Pseudosmodingium, Rhus), diplostemonous (Lithrea, Mauria, Schinus), or reduced to four stamens (Anacardium excelsum) or a single (Mangifera indica, other Anacardium spp.) fertile stamen. In some taxa (Anacardium, Mangifera), additional sterile stamens are present. The gynoecium of Anacardioideae is typically trimerous and the ovary pseudomonomerous formed by one carpel with a fertile locule and ovule and two sterile carpels reduced to more or less well-developed styles and stigmas (Wannan and Quinn 1991;Bachelier and Endress 2009;Tölke et al. 2021a). However, pseudomonomerous gynoecia have also been reported in Neotropical Spondioideae, in which species usually have carpel dimorphism and reduction in the number of fertile ovules (e.g., some Cyrtocarpa s.l. spp., Tapirira). Truly monomerous gynoecia have been reported in both subfamilies (e.g., Campnosperma in Spondioideae, or Anacardium and Mangifera in Anacardioideae) (Wannan and Quinn 1991;Bachelier and Endress 2009;Tölke and Demarco 2020;Tölke et al. 2021a).
In all Anacardiaceae, each fertile locule typically contains a single apotropous ovule (or also syntropous, see Endress 2011). The ovule is regularly bitegmic and crassinucellate with a round inner integument and a hood-shaped outer integument that sometimes has large lateral flaps. However, some Anacardioideae are unitegmic, as in Mangifera and Anacardium where the ovule is also pachychalazal, or in Pistacia, Amphipterygium, and Orthopterygium where the funicle tends to increase dramatically in size after fertilization and form large spongy tissue (Bachelier and Endress 2007;Herrera and Bachelier 2016). After fertilization, the development of the endosperm is free nuclear (Copeland 1959(Copeland , 1961. However, the endosperm is usually entirely consumed during embryo development and mature seeds are typically exalbuminate. The dicotyledonous embryos are usually well-developed and are up to 5 cm in length and weigh about 20 g in some cultivars of Mangifera (Kennard 1955).
Breeding systems. In both subfamilies, flowers can be functionally unisexual with rudimentary stamens or carpels (type I sensu Mitchell and Diggle 2005) and are thus more or less cryptic (Wannan and Quinn 1991;Endress 2007, 2009). Herein, we refer to vestigial gynoecia as pistillodes because this term is used much more widely than carpellodes, which may sometimes be more accurate and is somewhat gaining popularity in use. Flowers that are morphologically and functionally unisexual with no vestigial stamens or carpels (type II sensu Mitchell and Diggle 2005) are only found in Astronium section Astronium and in a few other Anacardioideae taxa (Pistacia, Amphipterygium, Orthopterygium) that are strictly wind-pollinated (Barkley 1968;Bachelier and Endress 2007;Pell et al. 2011;Weeks et al. 2014;Mitchell and Daly 2017, Joyce unpublished data).
There is a tremendous diversity of flower morphologies and breeding systems in Neotropical Anacardiaceae. In Spondias, for example, breeding systems include hermaphrodite in S. dulcis, andromonoecious in S. tuberosa (Nadia et al. 2007) and S. macrocarpa Engl. (Tavares et al. 2020), and dioecious in S. purpurea (Bachelier and Endress 2009;Pell et al. 2011;Mitchell and Daly 2015). The literature for S. mombin is even more complicated with some studies describing it as gynodioecious (Tavares et al. 2020) and others as andromonoecious (Ramos 2009). In Pistacia, where unisexual flowers are of type I (Mitchell and Diggle 2005), a study recently found a range of breeding systems across the genus and even within species (Bai et al. 2019). These included hermaphrodite, dioecious, monoecious, gynomonoecious, and trimonoecious.
Perianth. In both subfamilies, sepals tend to be connate at the base, whereas petals are usually entirely free. The perianth is most commonly glabrous, although in some taxa it 1 3 is pubescent only on the sepals (e.g., Tapirira) or on both petals and sepals (e.g., Actinocheita, Campnosperma, Thyrsodium) (Wannan and Quinn 1991;Bachelier and Endress 2009;Pell et al. 2011). Peltate scales are reported on the flowers of Tapirira lepidota and on the ovary of Campnosperma (Bachelier and Endress, 2009;Hammel et al. 2014).
In most Anacardiaceae, petals often become longer than the sepals during floral development and take over the protection of the inner reproductive organs. However, the sepals are persistent and greatly enlarged in the fruits of Astronium (Leite 2002;Mitchell and Daly 2017) and aid dispersal. In some wind-pollinated members of Anacardioideae, the perianth can be reduced to a single whorl of organs interpreted as tepals in Haplorhus , sepals in male flowers of Amphipterygium and Orthopterygium, and sepals or bracts in Pistacia (Bachelier and Endress 2007). Only rarely is the perianth entirely lacking, as in female flowers of Amphipterygium and Orthopterygium (Bachelier and Endress 2007;Herrera and Bachelier 2016).
Androecium. In virtually all Anacardiaceae, stamens are free, and only in Anacardium the bases of the filaments fuse together and form a short staminal tube around the ovary. In all members of the family with a diplostemonous androecium, stamens often appear to be arranged in a single whorl around the disk, with antepetalous stamens regularly shorter than the antesepalous ones (Wannan and Quinn 1991;Bachelier and Endress 2009). In haplostemonous flowers, the single whorl of stamens is usually facing the sepals and alternating with the petals (e.g., Actinocheita, Astronium, Comocladia, Cotinus, Loxopterygium, Pseudosmodingium, Rhus, and Toxicodendron). Even in flowers with a single perianth whorl, stamens are either facing sepals (or bracts) like in Pistacia, or alternating with perianth lobes interpreted as sepals in male flowers of Amphipterygium and Orthopterygium (Bachelier and Endress 2007). In Mangifera and Anacardium, the fertile androecium comprises only one fertile antesepalous stamen that is distinctively larger than the others, which are often reduced or sterile (Wannan and Quinn 1991;Bachelier and Endress 2009;Tölke and Demarco 2020).
Stamens are usually glabrous, but the filaments of some species (e.g., Anacardium excelsum, some Thyrsodium) and the anthers of others (e.g., Amphipterygium, Orthopterygium) are pubescent (Bachelier and Endress 2007;Herrera and Bachelier 2016). Anthers of all Anacardiaceae are bithecal, tetrasporangiate, and usually H-shaped or sometimes sagittate. The dorsal side of the theca is often more or less larger than the ventral one, and anther dehiscence is latrorse to ventrorse with a longitudinal dehiscence line extending from the tip down to the base of each theca. The connective can be conspicuous as in some Cyrtocarpa. Anthers are either connected at the base (basifixed) or on the median dorsal side (dorsifixed) and may be more or less versatile as in Spondias and Tapirira in Spondioideae, or Anacardium and Mangifera in Anacardioideae (Bachelier and Endress 2009;Tölke et al. 2021a).
Pollen is usually tricolporate and spheroidal with long, narrow colpi, with or without ornamentation. In part because of their distinct pollen morphologies, the wind-pollinated genera Amphipterygium, Orthopterygium, and Pistacia have historically been segregated as the distinct families Julianiaceae (Amphipterygum and Orthopterygium) and Pistaciaceae (Pistacia). Adapted for wind dispersal, their pollen grains thus have a large number of small, shallow colpi, much like a golf ball, in contrast to those more typical of insect-pollinated genera which typically have a combination of striations and reticulations. For additional information on Anacardiaceae pollen, see Heimsch (1940), Marticorena (1968), Anzótegui (1971), and Olivera et al. (1998).
Intrastaminal disk, osmophores, and secretions. The flowers of most Anacardiaceae have an intrastaminal disk, often referred to as a nectary disk. In the Neotropics, it is missing in Amphipterygium, Anacardium, Orthopterygium, and Pistacia and is extrastaminal in Mangifera (Bachelier and Endress 2007). When present, the disk is typically more or less fleshy and lobed between the bases of the filaments and the gynoecium, and smooth to extremely papillate. The surface is usually glabrous and may be densely covered in stomata that are sometimes referred to as nectarostoma because of their secretory function (Wannan and Quinn 1991;Bachelier and Endress 2009;Tölke et al 2018b;Tölke and Demarco 2020). Mangifera has an extrastaminal nectary disk that is sometimes described as five antesepalous fleshy lobes. Anacardium flowers lack a disk, but have multicellular glandular trichomes. Both genera have osmophores on the base of their petals, which were recently reported for the first time in the family (Tölke et al. 2018a).
The role of the intrastaminal disk as a nectary has long been assumed. A comparative study in seven genera and thirteen species encompassing both subfamilies of Anacardiaceae recently confirmed this by showing that the secretions contain at least three sugars (Tölke et al. 2018a(Tölke et al. , b, 2021b. They found that relative concentrations of fructose, glucose, and sucrose are more or less the same in different floral morphs of the same species, but vary strongly from one species to another. In most species, other substances such as lipids and/or phenolic compounds are also part of these mixed secretions, and in Tapirira guianensis, the disk persists in young fruits but produces only lipids and no sugars (Tölke et al. 2015(Tölke et al. , 2018b. However, whether these mixed secretions could also produce a floral scent remains unknown, and their potential evolutionary and ecological significance needs to be evaluated in the context of the most recent phylogenies of the family. Gynoecium. In Anacardiaceae, the gynoecium is typically syncarpous and comprises a single ovary with as many styles and stigmas as there are carpels. In addition, there are usually as many carpels as there are petals in Spondioideae; whereas, in Anacardioideae the gynoecium typically comprises three carpels, out of which only one is fertile and forms a locule and the other two are reduced each to a style and stigma. Anacardioideae gynoecia are thus typically pseudomonomerous, whereas truly pseudomonomerous (unilocular) gynoecia are relatively rare in Spondioideae and, to date, have been documented in New World taxa only in Tapirira (Wannan and Quinn 1991;Bachelier and Endress 2009;Tölke et al. 2021a) and some species of Cyrtocarpa (Herrera et al. 2018). In some Spondioideae (e.g., Attilaea and some Cyrtocarpa), not all carpels are fertile and often only one seed is produced, while in others (e.g., Antrocaryon and Spondias) all carpels typically produce seed (Herrera et al. 2018;Tölke et al. 2021a). The gynoecium can be truly monomerous in both subfamilies, as in Campnosperma in Spondioideae, and in Anacardium, Mangifera (Wannan and Quinn 1991;Pell 2004;Bachelier and Endress 2009;Tölke and Demarco 2020), and other members of Anacardioideae (e.g., Orthopterygium; Herrera and Bachelier 2016).
In Anacardioideae, the asymmetric development of the carpels makes it difficult to compare their pseudomonomerous gynoecia to other syncarpous gynoecia in Spondioideae, where all carpels usually develop more or less symmetrically (at least up to ovule initiation or rarely earlier). In most Anacardioideae, the bases of the three styles are usually united above the ovary and form a symplicate zone with an internal compitum. Whereas in Schinopsis, the unusual development of the ovary above the single locule and the displacement and separation of the three styles and stigmas prevents the formation of a symplicate zone and internal compitum. There is also no symplicate zone or internal compitum in any syncarpous gynoecia of Spondioideae, in which all carpels either form a locule and share a welldeveloped synascidiate zone or like in Tapirira, they form a pseudomonomerous gynoecium (Bachelier and Endress 2009;Tölke et al. 2021a). Sometimes, as in Spondias purpurea, the synascidiate zone exposes the former center of the floral apex between the free styles and stigmas (Bachelier and Endress 2009).
Ovule and ponticulus. A defining feature of Anacardiaceae is the presence of a single ovule per locule. It is typically pendulous and anatropous (syntropous), and curved with the micropyle facing the base of the funicle below its connection to the median axile and apical placenta. Only in some taxa the insertion of the ovule is lower, toward the base of the inner ventral side of the locule, as in Anacardium, Mangifera, or Pistacia (Bachelier andEndress 2007, 2009). In all Anacardiacaeae studied to date, the funicle always appears relatively long and with a bend on the dorsal side that comes in close contact with the base of the style and the pollen tube transmitting tract and sometimes even forms a dorsal projection resembling the fin of a shark (Bachelier and Endress 2009). This zone of contact is called the ponticulus because it may function as a bridge in the pollen tube pathway between the base of the style and the ovule. In contrast with other angiosperms in which the pollen tube enters the locule and follows the morphological surface of the ovule until it reaches the micropyle, in some Anacardiaceae one pollen tube can penetrate directly inside the funicle via the ponticulus and follow the trace of procambium up to the chalaza and the female gametophyte (de Wet et al. 1986;Gonzalez 2016, Lora et al. 2021. To date, the ponticulus has only been looked for and documented in a few genera of Anacardioideae and seems not to be functional in Spondioideae studied to date ). More research on the ponticulus is needed to determine whether or not it is a synapormophy for any Anacardiaceae clades and has any functional or evolutionary significance.
In Anacardiaceae, ovules are crassinucellar and regularly bitegmic. Unitegmic ovules have only been reported in a few genera of Neotropical Anacardioideae (Amphipterygium, Anacardium, Mangifera, Orthopterygium, Pistacia), and while the developmental origin of their single integument is still debated, it seems to be often associated with pachychalazy Endress 2007, 2009, andreferences therein). However, pachychalazal seeds have also been reported in genera with bitegmic ovules (see below). In bitegmic ovules, the inner integument is typically circular and forms a straight endostome, while the outer integument is rather hood-shaped, sometimes with two more or less flattened "flaps" and an exostome that is variable in form (Bachelier and Endress 2009). In some genera, the funicle is massive (Amphipterygium and Pistacia) and develops a basal (lower) appendage, sometimes with lobes, that expands dramatically after fertilization (Bachelier and Endress 2007).
Fertilization is typically porogamous (through the micropyle). However, in some Anacardioideae it is chalazogamous, especially in genera where a functional ponticulus has been documented (Copeland 1961;Aleksandrovski and Naumova 1985). The function of the ponticulus has not yet been investigated in all species in which it has been documented. In Schinopsis balansae, an intermediate pathway called chalazoporogamy was described recently for the first time in the family (Gonzalez 2016). All species studied to date typically have a single monosporic Polygonum-type female gametophyte, which after fertilization yields a single embryo and a triploid free nuclear endosperm (Johri 1963).
Fruits and seeds. In Neotropical Anacardiaceae, fruits are typically drupes or samaras (rarely syncarps, utricles, nutlike, or baccate) that are fleshy or dry. Fruits of the family are often edible (e.g., Antrocaryon, Cyrtocarpa, Mangifera, Rhus, Schinus, Spondias, Tapirira). The exocarp varies in thickness and may be soft to lignified, pubescent or glabrous, and variously colored. It is brittle and separates from the mesocarp at maturity in some taxa (Lithrea, Schinus, Toxicodendron). The mesocarp is typically fleshy or fibrous and varies in thickness; it is edible in a number of species. In taxa that cause dermatitis, the mesocarp often has resin canals appearing brown or black, also called secretory ducts (e.g., Anacardium, Comocladia, Lithrea, Metopium, Toxicodendron).
Endocarps can be chartaceous, fibrous, cartilaginous, or bony, sometimes with opercula in Spondioideae. Wannan and Quinn (1990) described two anatomically distinct endocarp types that corresponded to the two subfamilies. The Spondias type typically has irregularly oriented sclerenchyma and is lignified, and the Anacardium type is regularly oriented into discrete layers including palisadelike sclereids. However, a recent comparative study of fruit anatomy in Spondioideae showed that the endocarps of Campnosperma (and Paleotropical Buchanania) are quite distinct from those found in other members of the subfamily (Herrera et al. 2018). Another study detailed the endocarp secretions produced in various stages of development in Tapirira guianensis Aubl. (Tölke et al. 2017), highlighting their potential role in seed protection and dispersal.
All Anacardiaceae typically produce a single seed per locule. Thus, in Anacardioideae, the fruit typically contains a single seed, whether the locule is derived from a pseudomonomerous or monomerous gynoecium Quinn 1990, 1991;Endress 2007, 2009). In contrast, the number of fertile carpels varies from one to several in Spondioideae. Attilaea and some Cyrtocarpa have more than one locule but produce only one seed (Martínez and Ramos 2007;Herrera et al. 2018), whereas Antrocaryon and Spondias have five or more locules and typically produce five seeds. In species of Pistacia (Verdù and Garcia-Fayos 1998), Schinopsis (González and Vesprini 2010), and Spondias (Juliano 1932), parthenocarpic development of seedless fruits is common and a study of a member of the sister family Burseraceae suggests that parthenocarpy may be more common in both families and may have an adaptive value to avoid seed predation (Ramos-Ordoñez et al. 2012).
Native Neotropical Anacardiaceae seeds vary in length from 2 mm to more than 4 cm and are typically straight or curved. Endosperm is generally lacking, and the seeds are exalbuminate, with a well-differentiated dicotyledonous embryo. Germination occurs through irregular or regular splitting of the endocarp or via specialized mechanisms (many of which are opercula) that open small portions of the endocarp (Hill 1933(Hill , 1937. Opercula are found only in Spondioideae; they are usually apparent on the endocarp surface, but are covered by fibrous endocarpic and mesocarpic projections in some Spondias taxa. In Neotropical Anacardiaceae, the whole operculum detaches with the emerging radicle (e.g., Antrocaryon, Cyrtocarpa, Spondias; Hill 1933Hill , 1937Herrera et al. 2018). Germination in Neotropical Anacardiaceae is typically epigeal, as in the rest of the family, but may be hypogeal, and in both types the plano-convex (rarely flat) cotyledons are equal in size, free, and may be either cryptocotylar or phanerocotylar, typically straight or curved (Carmello-Guerreiro and Paoli 1999;Garwood 2009).
Secretory ducts. In all Anacardiaceae, secretory ducts (resin canals) are derived either from the phloic procambium in vegetative and reproductive structures, or from the ground meristem behind the shoot or root apical meristem (medullary meristem). Their development can also vary from schizogenous to lysigenous, and authors often have different interpretations of similar results. For instance, their development is described as schizolysigenous in stems of Anacardioideae, such as Anacardium, Rhus (Copeland 1961;Paula and Alves 1973), and the invasive Toxicodendron succedaneum (L.) Kuntze (Harada 1937). Other studies of Anacardium (Nair et al 1983), Toxicodendron (McNair 1918), and Schinus (Venning 1948) reported their development as being schizogenous. However, Anacardium hypocarp secretory ducts were reported to be lysigenous (Varghese and Pundir 1964), as were vegetative and reproductive organs of Mangifera (Venning 1948;Fahn and Joel 1976), and shoots of Schinus (Joel 1978).
The development of secretory ducts seems to be independent from their origin, but there appears to be a correlation between their derivation and the type of secretions they produce. Tölke et al (2021a, b) found that in Anacardium, Lithrea, Spondias, and Tapirira, ducts originating from phloic procambium tend to secrete lipids (resin sensu stricto of Tölke et al. 2021b), and those derived from ground meristem tissue tend to secrete mostly carbohydrates (gums). In addition, they showed that the composition of phloic duct secretions also tends to be similar in both vegetative and reproductive structures and are often a mix of compounds (e.g., lipids and carbohydrates) that are collectively referred to as resin sensu lato, like those of the medullary ducts of Tapirira. However, gums comprising only polysaccharides were also identified in medullary ducts of Anacardium and Spondias, and a resin sensu stricto comprising only lipids was found in fruits of Anacardium. Given these results, the current classification of mixed secretions should not be used for taxonomic inferences (Tölke et al. 2021b).

Ecology
Distribution and habitats -Neotropical Anacardiaceae are distributed from southern Canada and the USA in North America south to the West Indies and South America. All Spondioideae occur in subtropical and/or tropical habitats, while Anacardioideae are found in temperate, subtropical, and/or tropical habitats. Some species, such as Malosma laurina (Nutt.) Nutt. ex Abrams, Metopium toxiferum (L.) Krug & Urb., Pistacia mexicana Kunth, multiple species of Rhus, Toxicodendron radicans, and T. diversilobum (Torr. & A.Gray) Greene, occur primarily in temperate and/or subtropical areas of the USA and extend into the Neotropics. Of these, Metopium toxiferum, Rhus copallinum L., and Toxicodendron radicans occur on both the mainland and in the West Indies. Lithrea, Schinopsis, and Schinus are the southernmost genera, occurring primarily in the subtropics and tropics, but also reaching temperate areas in southern South America. Schinus occurs as far south as Patagonia with taxa distributed in lowland habitats and a few reaching an altitude up to 4000 m.
Anacardiaceae adapted to living in dry habitats in the Neotropics are particularly rich in morphological diversity, which corresponds to greater taxonomic diversity in these habitats versus in wet habitats. The number of Anacardiaceae species in Neotropical dry habitats (e.g., caatinga, chaco, chaparral, campo rupestre, desert, grassland, matorral, Patagonian steppe, pine-oak forest, restinga, savanna, tropical dry forest) is nearly double the number in wet habitats (e.g., flooded forest, gallery forest, wet lowland and montane forests, tropical wet, and moist forests).
Organismal and ecological interactions -Ecological interactions occur between Neotropical Anacardiaceae and numerous other organisms including ants and other insects, mites, endophytic, and endomycorrhizal fungi, and a diversity of vertebrates. Anacardium has associations with endomycorrhizal and endophytic fungi (Faria et al. 2016), and endophytic fungi have been isolated from leaf blades of Astronium (mentioned as Myracrodruon), Schinus, and Spondias (Rodrigues and Samuels 1999;Lima et al. 2012;Pádua et al. 2019). Ants forage nectar from extrafloral nectaries of Anacardium and protect the plant against herbivores in this mutualistic relationship (e.g., Lacchia et al. 2016).
A great diversity of galls can be observed on South American Anacardiaceae, including barrel-shaped leaf rolls, lenticular, nipple-shaped, or pit galls on the leaves, or globoid or spindle-shaped galls enclosed within swollen stems. Anacardium, Astronium, Lithrea, Schinopsis, Schinus, Spondias, Tapirira, and Thyrsodium are particularly heavily attacked by insects, in some cases with host-specific gallinducing insect species ( Pollination syndromes. Most Neotropical Anacardiaceae are entomophilous, but wind pollination occurs in some members of Anacardioideae, such as Amphipterygium, Orthopterygium, and Pistacia. Some Anacardium, Astronium, and Schinus species are ambophilous (combination of insect and wind pollination; Torretta and Basilio 2009). Haplorhus appears to be at least partially wind-pollinated and may also be ambophilous, but additional study is needed for confirmation. Insects important for Anacardiaceae pollination in the Neotropics include bees (frequently stingless bees), wasps, and flies, with an assortment of other insects pollinating flowers to a lesser degree. Most Anacardiaceae flowers attract generalist pollinators, and in some cases multiple orders of insects have been found carrying the pollen of one taxon (Lenza and Oliveira 2005;Chiapero et al. 2021).
Anacardium species are typically pollinated by moths and butterflies (Mitchell and Mori 1987), and secondarily by bats (Gardner 1977). Heteranthery has been documented in Anacardium and Mangifera where some species have emergent large stamens and a set of smaller stamens, both of which have pollen (Mitchell and Mori 1987).
Dispersal. Both animal and wind dispersal are prevalent in Neotropical Anacardiaceae. Nineteen of the 32 genera have fleshy, vertebrate-dispersed drupes. The rest of the genera are wind-dispersed, or their mechanism of dispersal is yet to be determined.
Like wind pollination, wind dispersal is found exclusively in Anacardioideae, but the two only occur together in Amphipterygium and Orthopterygium. Wind-dispersed taxa display a variety of morphological adaptations that evolved for this purpose (Weeks et al. 2014). These include subtending enlarged sepals (Astronium), trichome-covered margins on a globose fruit (Actinocheita), laterally compressed samaras with trichome-covered margins (Ochoterenaea), samaras with two lateral wings (Cardenasiodendron, Pseudosmodingium), samaras with a single lateral wing (Loxopterygium, Schinopsis), and dry samaroid syncarps of nutlets (multiple fruit, Amphipterygium, Orthopterygium; Augspurger 1986, Burnham andCarranco 2004). Wind is the most likely dispersal mechanism of the small, dry fruit of Apterokarpos (a dry achene-like drupe without a wing) and Pachycormus (dry utricle fruits), but reports for these are lacking and further research must be done to confirm this conjecture.
Wind-dispersed Anacardiaceae genera are often associated with tropical dry forests (Actinocheita, Amphipterygium, Apterokarpos, Astronium, Cardenasiodendron, Loxopterygium, Pseudosmodingium, Schinopsis) or other types of arid habitats (Orthopterygium; Weeks et al. 2014). Some of these wind-dispersed genera have species that occur in moist habitats like tropical moist forests and tropical rain forests as well. In these habitats, the species tend to be emergent or canopy trees (e.g., Astronium concinnum Schott, A. glaziovii Mattick, A. graveolens, A. lecointei Ducke, A. obliquum Griseb., A. ulei Mattick, Loxopterygium sagotii Hook.f.). The winged fruits of Schinopsis balansae Engl. have been recorded as traveling 60-150 m away from the parent tree (Galarza 1915). In some cases, wind-dispersed fruits are consumed by animals that may or may not also disperse the seed (macaws, Pitter and Christiansen 1995;parrots, Villaseñor et al. 2010).
Rodents and parrots mostly function as seed predators rather than dispersers, but they do occasionally effectively disperse seeds (e.g., agoutis; Smythe 1970). Bearded capuchin monkeys in Brazil have been reported as seed predators, and they have been observed using tools to open the endocarps of Anacardium (Luncz et al. 2016). Some birds, such as macaws and parrots, have beaks strong enough to break open even very hard Anacardiaceae endocarps and eat the seeds inside (e.g., Ragusa-Netto 2011).
Anacardium has an especially interesting adaptation that facilitates animal dispersal: an enlarged edible hypocarp that subtends the drupe. This vegetative structure is a fleshy, expanded pedicel and is the source of cashew juice. One species of Anacardium, A. microsepalum Loes., grows in the flooded forests of the Amazon and lacks a hypocarp. The fruits fall into the water at maturity and may be fishdispersed (Mitchell and Mori 1987), but are more likely fishpredated and water-dispersed (Gottsberger 1978).
Conservation -As with other threatened plants, the primary drivers endangering Neotropical Anacardiaceae are habitat loss and overexploitation, primarily for wood and charcoal harvesting. There are eight species of Neotropical Anacardiaceae currently listed as Endangered (EN) by the International Union for Conservation of Nature (IUCN); however, some of these are in need of further evaluation. Haplorhus peruviana Engl. occurs in inter-Andean valleys on the western slope of the Andes from central Peru south to northern Chile and has been determined by the IUCN to be Endangered. Similarly, Orthopterygium huaucui (A. Gray) Hemsl. is endemic to the western slope of the Andes in central Peru at mid-elevations and, although it has not yet been evaluated by IUCN, it is a Species of Concern due to habitat destruction (León et al. 2013). Species that are restricted to the Caatinga and other dry habitats in Central and South America are also under great pressure from habitat destruction and conversion to agricultural use. Taxa endemic to islands are also under particular threat due to habitat loss. For example, numerous taxa in Jamaica are listed as Near Threatened to Critically Endangered (e.g., Comocladia cordata Britton, C. parvifoliola Britton, C. velutina Britton). Tapirira chimalapana T. Wendt and J.D. Mitch. from Mexico is listed as Critically Endangered by the IUCN due to habitat loss in the wet forests in the area around the Isthmus of Tehuantepec.
Species that have not been evaluated by IUCN but are Species of Concern are Apterokarpus gardneri (Engl.) Rizzini, Cardenasiodendron brachypterum (Loes.) F.A. Barkley, Loxopterygium huasango Spruce ex Engl., Spondias admirabilis J.D. Mitch. and Daly, and Spondias expeditionaria J.D. Mitch. and Daly. Much work remains to be done to evaluate the conservation status of Neotropical Anacardiaceae. Many of the Caribbean islands have been particularly neglected, including most dramatically Cuba and Hispaniola.
Mauria provides a good case study for the importance of resolving taxonomic questions in preparation of conservation assessments. Several species of Mauria are listed by IUCN, but the genus is in need of taxonomic revision. Unfortunately, some IUCN assessments are based on incorrect or unresolved taxonomy. Schinopsis haenkeana Engl. is listed as vulnerable, but it is a synonym of Schinopsis marginata Engl., which is not listed (Hunziker 1998). Further confusing this issue is that Schinopsis quebracho-colorado (Schltdl.) F.A. Barkley and T. Mey. is listed as being of Least Concern by the IUCN, but the correct name for this taxon is Schinopsis lorentzii (Griseb.) Engl. (Mogni et al. 2017), and Schinopsis marginata is recognized within it by some authorities.

Paleobotany
Due to its fossil diversity, prevalence, and uniquely identifying characters, Anacardiaceae have been the focus of many paleobotanical studies. The family is well-represented in the fossil record by wood, leaves, flowers, pollen, and fruits. Studies of these fossils have contributed to a better understanding of the family's evolution and biogeography (e.g., Weeks et al. 2014). This evidence points to a Cretaceous origin of the family, which is present in the fossil record through the Cenozoic. Martínez-Millán (2000) proposed a Southeast Asian origin for the family, but this finding is somewhat controversial given the fossil record that has been discovered to date and some contradictory phylogenetic data (see Phylogeny, Taxonomy and Evolution section above).
As with all organisms, not all Anacardiaceae fossil identification should be treated with the same degree of confidence. Because our taxonomic system is based on reproductive characters, fruit and flower fossils are somewhat easier to assign to an extant taxon than are vegetative fossils. Within Anacardiaceae, wood fossils have proven to be particularly challenging due to the similarity of Burseraceae and Anacardiaceae wood (Kryn 1952;Terrazas 1994). For these reasons, some fossils identified in the literature as Anacardiaceae need to be reevaluated.
The fossil record shows that Anacardiaceae were an important component of Paleogene floras in various parts of the world (Manchester 1999). The family was particularly widespread during climatically warm intervals of the Eocene in Europe and North America (Manchester 1994;Collinson and Cleal 2001). As with other organisms, some Anacardiaceae fossil evidence reported in the literature is suspect and requires reevaluation (see Supplementary Information for additional references).
Anacardiaceae are an important element of the Paleocene flora of the Salamanca Formation in Chubut Province, Argentina (Iglesias et al. 2021). This flora was first interpreted by Berry in 1937, but some of his identifications are questionable. Iglesias et al. (2021) used a more robust set of morphological characters to taxonomically compare and assign the fossils in this flora to extant genera. For example, diagnostic leaf architectural characters, such as admedial branching of the tertiary veins and the presence of an intramarginal secondary vein, were used for identifications. Iglesias et al. (2021) assigned some of the fossil specimens to extant genera currently restricted to the Paleotropics including Sorindeia, Dracontomelon, and Micronychia.
Fossils of Rhus, a currently widely distributed genus in the Northern Hemisphere, are found as fossilized wood, leaves, pollen, and fruit from the Eocene through the Miocene-Pliocene from the Northern Hemisphere (see additional references). This stratigraphic range includes the Eocene in Western North America, the Oligocene of North America and Europe, and the Miocene-Pliocene of Europe (Wolfe and Wehr 1987; Meyer and Manchester 1997;Tosal et al. 2019 (Meyer and Manchester 1997).
Various early Eocene samples of Rhus fossil leaves have also been described from the Republic flora of Washington, USA that have leaf characteristics comparable with extant species (Flynn and DeVore 2019). These include shape, margin, venation, and a winged petiole. This study provides the earliest documentation (early Eocene) of hybridization within Rhus (Flynn and DeVore 2019). Manchester (1994) described silicified endocarps of sumac fruits (Rhus rooseae Manchester) from the middle Eocene Nut Beds Flora, Clarno Formation, Oregon. His work was the first report of fossilized Anacardiaceae fruits in North America.
Several other Anacardiaceae genera also make their appearances in the Eocene. In the Florissant deposits in Colorado (USA), a fossil leaf was identified as Cotinus fraterna (Lesquereux) Cockerell due to its cladodromous secondary venation (Meyer 2003). From the early Middle Eocene of Messel, Germany, there are reports of compressed fruits of Anacardium (Manchester et al. 2007), a genus that is today restricted to the Neotropics (Mitchell and Mori 1987). The fossil shares characters with extant Anacardium that in combination are diagnostic: a reniform drupe with a subtending enlarged pedicel called a hypocarp (''cashew apple''). Previous reports of Anacardium were described from leaves by Berry (e.g., 1924a, b) in the fossil record of Texas, USA and in northern South America. Manchester (1977) described fossil wood of Tapirira from the Eocene of the Clarno Formation in Oregon, USA. This is the oldest record for the genus. The form genus Bosquesoxylon from the Eocene of Chiapas, Mexico, is based on wood fossils (Pérez-Lara et al. 2017).
Diverse Oligocene fossil leaves of Anacardiaceae have been reported from Tepexi de Rodríguez, Puebla, Mexico. These samples were assigned to Pseudosmodingium, Haplorhus, Rhus, Comocladia, and Pistacia. The diagnostic characters include several leaf architectural features: asymmetrical lamina, pinnate primary venation, craspedodromous or cladodromous secondary venation, poorly developed areolation, and entire or serrate margin. These fossils indicate that Anacardiaceae were a diverse and important component of the Oligocene flora (Ramírez et al. 2000;Ramírez and Cevallos-Ferriz 2002). The form genus Llanodelacruzoxylon from the Oligocene-Miocene of Panama is based on fossilized wood (Rodríguez-Reyes et al. 2020). Tapirira has also been reported from permineralized wood from the Oligocene-Miocene of Baja California Sur, Mexico (Martínez-Cabrera and Cevallos-Ferriz 2004), and Miranda (1963) depicted a complete flower embedded in amber from the late Oligocene and early Miocene of Simojovel de Allende, Chiapas, Mexico.
Anacardiaceae Miocene fossil fruits have been reported from Panama and Ecuador. Permineralized endocarps belonging to the subfamily Spondioideae have been found in Panama (Herrera et al. 2019), including Spondias, Antrocaryon, and Dracontomelon. The first two have extant disjunct distributions between the Neotropics and Paleotropics, while the third is currently restricted to the Paleotropics. From Ecuador Burnham and Carranco (2004) described laterally winged fossil fruits with a remnant stigma on the backbone of the wing as a new species of Loxopterygium (L. laplayense Burnham and Carranco). This record is the only known fossil evidence of wind dispersal in the Anacardiaceae, and the authors suggest that their findings support the hypothesis that tropical dry forests date back to the Miocene in this area.
In Patagonia, Argentina, fossil leaves/leaflets from the middle Miocene were identified as Lithrea, which is extant and endemic to South America. The identification was possible because of leaf architectural features, such as craspedodromous secondary venation, several secondary veins (some of them forming exmedial branching), parallel intersecondaries, and acute cuneate to decurrent base (Passalia et al. 2019).

Economic botany and phytochemistry
The Anacardiaceae have a rich diversity of uses, primarily involving their edible fruits, phytochemistry, and wood (Sweet and Barkley 1936;Gillis 1975). Indigenous people have utilized Neotropical Anacardiaceae for millennia for food, firewood, timber, medicine, and many other purposes. These plants have also been the subject of much research investigating compounds that are useful and/or injurious to humans.
Edible plants -Neotropical Anacardiaceae include a few fruits of global significance, with cashew, Anacardium occidentale, being the most well known and widely utilized. The seed of A. occidentale (cashew nut) is a valuable agricultural commodity, with an estimated global value reaching over $2.75 billion USD in 2018 (FAOSTAT). Despite cashew being native to Brazil, global production of cashew nut is highest in South and Southeast Asia and sub-Saharan Africa. Beyond direct consumption of cashew nuts, cashew milk, oil, and butter are important food products, and trends toward plant-based diets have also highlighted cashew's utility in vegan alternatives to animal products like cashew cheese. The hypocarp of A. occidentale, commonly called cashew apple, is also an important crop, with an estimated value of $272 million USD in 2018 (FAOSTAT). Cashew apples are eaten fresh or used to make juice, jam, or jelly. Widely popular in Brazil, cashew apple is beginning to gain popularity in other regions of the world (Strom 2014 Since its introduction in the 1700s, mango (Mangifera indica) has become one of the most economically important species of Anacardiaceae in the Neotropics, with a combined regional production value of over $1 billion USD in 2018 (FAOSTAT). Along with cashew and mango, the fruits of the Neotropical species Spondias mombin and S. purpurea are also global crops. The introduced range of cultivation of S. purpurea is limited to the Philippines, where the species was introduced by the Spanish in the sixteenth century, while S. mombin is cultivated throughout Southeast Asia and in parts of sub-Saharan Africa. Other species of Spondias are consumed locally in the Neotropics, including S. tuberosa (umbu), S. globosa J.D. Mitch. and Daly (taperibá), S. testudinis J.D. Mitch. and Daly (cajarana, cajá do jabuti), and the non-native S. dulcis (cajarana, jobo dos Indios) (Lévi-Strauss 1952;Mitchell and Daly 2015). Fruits of Spondias species can be eaten fresh, but are typically processed into juice, jam, pulp, and ice cream, or are sometimes used to make a slightly fermented alcoholic beverage (Ramírez-Guzmán et al. 2019). A minor yet noteworthy global product, pink peppercorn, is a gourmet spice produced from the dried drupes of two Schinus species, S. areira and S. terebinthifolia (Giuffrida et al. 2020). The drupes of these Schinus species are prized for their complex flavor profile with fruity, evergreen/pine, citrus, and spicy notes, and are an alternative to black peppercorn. Additionally, the essential oils derived from pink peppercorns are marketed for aromatherapy and used in perfumery (Giuffrida et al. 2020).
Numerous other species of Neotropical Anacardiaceae are important local sources of food and medicine.  (Kramer 1957;Casas et al. 2001;Chamorro and Ladio 2020).
Phytochemistry -Compounds identified in and isolated from Anacardiaceae are used in traditional and Western medicine, industrial applications, cosmetics, nutrition, textile dyes, leather and wood preservation, and cultural applications and have been the basis of taxonomic publications. Anacardiaceae are also well known for causing contact dermatitis (see review below and Mitchell 1990) and nut allergies (cashew and pistachio seeds; see Weinberger and Sicherer 2018 for a review).
Prior to the invention of PCR and widespread application of DNA-based phylogenetic studies, phytochemistry was an important taxonomic tool for understanding the evolution of the Anacardiaceae. For example, comparative analysis of flavonoids was used in placing Julianiaceae (Amphipterygium and Orthopterygium) in the cashew family (Wannan and Quinn 1988). Serotaxonomy was another line of evidence used to place the Julianiaceae within Anacardiaceae (Peterson and Fairbrothers 1983). David Young combined the study of flavonoids and morphology in his taxonomic study of Rhus subgenus Lobadium, which is particularly diverse in Mexico (Young 1976(Young , 1979. There is a diversity of industrial uses for extracts of Neotropical Anacardiaceae, especially of the exudate extracted from cashew mesocarp (cashew nutshell liquid), for which the global market value is predicted to reach $489.63 million by 2026 (Fior Markets 2020). Uses of cashew nutshell liquid are primarily petrochemical alternatives such as plant-based plastics and fuel (Lomonaco et al. 2017;Krishnan 2020), but also include other applications such as larvicides (Vani et al. 2018). Other Anacardiaceae have been investigated for industrial product development, such as insecticides, cosmetics, meat additives, nematicides, chromatographic gels, and adhesives (Lima et al. 2002;Ferrero et al. 2006, and see additional references). Tannin extracts from Schinopsis are used in a variety of applications from food additives to improve color and shelf life (Fruet et al. 2020), to tanning agents to dye and preserve wood and leather, to dietary supplements to reduce bovine flatulence (Beauchemin et al. 2007). The high tannin content of Schinopsis (Streit and Fengel 1995) makes it a popular rot-resistant wood for outdoor applications such as posts, poles, and railroad ties (Barberis et al. 2012). Schinopsis wood has many interesting properties that make it useful. The specific gravity of some taxa is so high (1.00 to 1.28) that the wood sinks in water (Muñoz et al. 2019a, b), and it is an excellent source of dendroclimatological data (López and Villalba 2016).
Medicinal uses -Traditionally and today, Neotropical Anacardiaceae are used, or have been investigated for potential use, as interventions for a variety of medical conditions. One of the most important traditional medicinal plants of this group is Amphipterygium adstringens (Schltdl.) Schiede ex Standl. (cuachalalate), the bark of which is widely used in Mexico and has also developed an international market as an anti-inflammatory, anti-bacterial, and obesity treatment (Oviedo-Chávez et al. 2004;Alonso-Castro et al. 2015). Both Schinus areira and Spondias mombin have been used as stimulants (Casas et al. 2001, wherein Schinus areira is called Schinus molle sensu lato, which we are recognizing as a synonym of Schinus areira in most cases and recognizing Schinus molle sensu stricto as being restricted to southern Brazil, Uruguay and northeastern Argentina). Other species of Schinus (S. fasciculata, S. longifolia (Lindl.) Speg., S. molle, S. terebinthifolia) appear commonly in surveys of folk medicine and are used for a wide range of ailments, including as an analgesic, anti-inflammatory agent, antiseptic, antiparasitic, sedative, digestive, and even (in the case of S. terebinthifolia, as an antidote for ciguatera fish poisoning (Kramer 1957, Casas et al. 2001, Ferrero et al. 2006, Trillo et al. 2010, Medeiros et al. 2018. Other commonly used taxa include species of Rhus (e.g., R. aromatica, R. ovata, R. pachyrrhachis Hemsl., R. standleyi F.A. Barkley and R. terebinthifolia), Schinopsis (e.g., S. balansae, S. brasiliensis Engl., S. lorentzii, S. marginata), and Spondias (e.g., S. mombin, S. purpurea, S. tuberosa) (Casas et al 2001;Albuquerque et al. 2007;Trillo et al. 2010;Wilken 2012;Alonso-Castro et al. 2015;Marisco and Pungartnik 2015).
For several genera, data are lacking in either the phytochemical analysis supporting the ability to cause contact dermatitis, or in reports of cases of contact dermatitis. For Actinocheita and Mosquitoxylum, urushiols have been isolated, and in Campnosperma alkylquinols have been found (Lamberton 1959), but we could find no Neotropical cases of contact dermatitis documented in the literature for Mosquitoxylum or Campnosperma. For Actinocheita, there are some reports of it causing a rash similar to other Neotropical Anacardiaceae genera (Medina-Lemos and Fonseca 2009). In Spondias, there are many reports of contact dermatitis, but no phytochemicals have been isolated that are known to cause this condition in humans.

Timber -
The most important timber-producing taxa within Neotropical Anacardiaceae are species of Astronium, commonly called gonçalo alves, muiracatiara, aroeira, or tigerwood because of characteristic dark stripes that run through the reddish wood (Molinos et al. 2021). Astronium species are widely available in the international market and have a variety of uses, including as flooring and veneers in furniture and cabinetry, and in knife handles, bows, pool cues, craft jewelry, and guitars (Meier 2021). The wood of Schinopsis is also harvested for timber, along with species of Anacardium, Antrocaryon amazonicum, Campnosperma panamense Standl., Loxopterygium sagotii, Metopium brownei (Jacq.) Urb., Schinus areira, Schinus molle, Spondias mombin, and Tapirira guianensis (Molinos et al. 2021).

Horticultural and invasive plants -A few species of Neotropical Anacardiaceae are common in the horticulture trade.
Pachycormus discolor is a popular species for bonsai and succulent enthusiasts (Rowley 1975), and seed is widely available from online retailers. Rhus integrifolia (Nutt.) Benth. & Hook.f. is used for hedges, Schinus areira is a popular ornamental tree that has become invasive in some areas, and Schinus polygama is also planted and of concern for its tendency to escape. Anacardium excelsum is planted in some Neotropical cities as a street tree. Rhus aromatica is planted widely, and there are numerous cultivars on the market; one of the most popular is Rhus aromatica "Gro-Low." Several Neotropical Anacardiaceae have great potential to be successful horticultural plants. Examples include numerous Schinus and Rhus species, Anacardium spruceanum Benth. ex Engl. with its beautiful white to pink bracts that subtend the inflorescence and give a similar appearance as poinsettia, Ochoterenaea colombiana F.A. Barkley has large purplefringed infructescences, and Actinocheita filicina has fernlike leaves and large red to purple infructescences. Some horticultural species have the potential to become invasive in their introduced ranges. This is the case for the Asian species Toxicodendron succedaneum, a popular street tree with bright fall foliage that is now considered invasive in Brazil and Cuba as well as other parts of the world (Rojas-Sandoval 2016). Native to central and eastern South America, Schinus terebinthifolia was introduced into the horticultural trade and has since become an extremely problematic invasive in many parts of the world including California, Florida, and Hawaii in the USA and in parts of the Caribbean, Australia, New Zealand, Portugal, and Spain (Morton 1978). Some evidence suggests that the success of S. terebinthifolia may in part be due to allelopathy (Morgan and Overholt 2005). Much research has been done to identify and test the effectiveness of biological controls for S. terebinthifolia (Wheeler et al. 2016). Schinus areira has also become naturalized and potentially invasive in parts of its introduced range (Bañuelas et al. 2019), and naturalization of S. polygama has been noted in California (Martin 2000). Lithrea caustica (Molina) Hook. and Arn. appears to be naturalizing at the University of California Santa Cruz Arboretum and Botanic Garden and is a taxon to watch as a nascent invasive (Mitchell personal observation).
Other uses -Beyond the uses stated above, Neotropical Anacardiaceae possess other attributes that make them an important component of ethnobotanical practices throughout their range. Species of Mauria contain a resin that is used to make candles, while the fruits of Cyrtocarpa were used to make a soap in the Aztec empire (Janick and Tucker 2018). Handicrafts are made from Pseudosmodingium andrieuxii and Spondias mombin (Casas et al. 2001), while Rhus aromatica is used for basketry (Wilken 2012) and Toxicodendron species are used for basket and textile dyes (Senchina 2006). Some Neotropical Anacardiaceae have religious significance, such as Astronium lecointei, which, in parts of northwestern Guyana, is used to drive away evil spirits (van Andel 2000). The macerated bark of Anacardium excelsum can reportedly be used as fish bait (Allen 1956), while Schinus fasciculata has been used in traditional veterinary medicine (Scarpa 2000). There are even historical accounts of Toxicodendron species being used in tattooing and other skin marking/dyeing practices, though the veracity of these reports may be questioned (Senchina 2006).
Four to five species in tropical dry forests in western Mexico south to northwestern Costa Rica.
Together with Orthopterygium, this genus is often segregated into the family Julianiaceae, but morphological and molecular data place it well within Anacardiaceae (Pell 2004;Bachelier and Endress 2007;Weeks et al. 2014).
Twelve or more species in tropical moist forest (including restinga and along rivers in sandy soils in the Amazon basin), gallery forest, rocky outcrops, and savanna (including cerrado and campo rupestre) in Honduras south to Paraguay, Brazil, and Bolivia.
Anacardium occidentale is cultivated pantropically. See Fig. 1 for illustrations of A. humile and A. occidentale.
A single species, A. gardneri, endemic to the Caatinga of Northeastern Brazil.
Eleven species in tropical dry to moist forests and savannas in Mexico south to Paraguay and northern Argentina. See Fig. 1 for illustrations of A. graveolens and Astronium urundeuva (Allemão) Engl. and Fig. 2 for illustrations of A. concinnum.
A single species, C. brachypterum, endemic to tropical dry forest in Bolivia.
Two species in the Neotropics (Cotinus chiangii (Young) Rzedowski & Calderón and Cotinus carranzae Rzedowski & Calderón) are endemic to open scrubland on steep limestone slopes of northern to central Mexico. Four species occur outside of the Neotropics: one in the temperate southern USA; one in central to southern Europe, east to China; and two in southwestern China. The two Mexican taxa are so morphologically distinct from Cotinus elsewhere (including the type species of the genus) and from each other, that they warrant further study to reevaluate their recognition in the same genus. The species outside the Neotropics have fruiting panicles that are wind-dispersed, much like a tumbleweed, via elongated plumose pedicels of numerous aborted flowers.
Sixteen Andean and Central American species from El Salvador south to eastern Venezuela and extreme northern Argentina, primarily in montane tropical forest.
Three species in the West Indies, southern Florida (US), Mexico, and northern Central America.
A single species, M. jamaicense Krug and Urb., southern Mexico south to northwestern Ecuador and Jamaica. Morphological and molecular evidence suggests that Mosquitoxylum is closely related to Rhus. There is one report of urushiol being present in this genus, but we can find no reports of M. jamaicense causing contact dermatitis (Aguilar-Ortigoza et al. 2003). Barkley, Bull. Torrey Bot. Club 69: 442 (1942).
A single species, O. colombiana, in Panama and Venezuela south to Bolivia.
Without nomenclatural conservation, the species name may change if Rhus samo Tul. is shown to be an earlier basionym, as expected.
A single species, O. huaucui, endemic to mid-elevation arid slopes of the Andes of western Peru.

Pachycormus Coville
A single species, P. discolor, endemic to patches of lava fields and on hillsides in the Sonoran Desert of central Baja California, Mexico.
One species in pine-oak forest, often associated with limestone, in Texas, USA, south to Guatemala. Eleven species in Mediterranean Europe, and North and East Africa; Southwest and Central Asia (former Soviet Republics) east to Afghanistan and temperate central and southern China, south to peninsular Malaysia and the Philippines.
Pistacia vera is cultivated in the Neotropics and worldwide in dry, warm climates.
Twenty-four or more species from southern Canada south to Panama and Cuba; two additional species restricted to temperate North America; one in North Africa to Mediterranean Europe east to Asia; six or more species from South Asia and western China east to Japan and Korea, south to Java and the Philippines; one endemic to the Hawaiian islands.
Seven species in dry forests of northern Peru, and sub-Amazonian and eastern Brazil south to central Argentina. Often the dominant canopy tree in Chaco forests of Bolivia, Paraguay, and northern Argentina.
Forty-two or more species, endemic to South America, ranging from the central Andes to southern South America, with exception of Schinus areira and S. terebinthifolia, which are native to this region but have become widespread invasive species outside their native range. Schinus species are distributed along the Andes in Argentina, Bolivia, Chile and Peru, where they can be found in the inter-Andean valleys and cloud forests, as well as at low altitudes from eastern Brazil to Patagonia. A few endemic Chilean species occur also in sclerophyllous forests under a Mediterranean climate. Schinus areira, S. polygama, and S. terebinthifolia are cultivated throughout the tropical, subtropical, and warm temperate regions of the world.
Six to seven species in lowland tropical moist forests east of the Andes in Colombia, Peru, Bolivia, southern and eastern Venezuela, the Guianas, and Amazonian and eastern Brazil.
Three species: two from southern Canada south to Mexico, one from Mexico to Bolivia. Two additional species in temperate North America; seventeen species in India and Nepal; Bhutan and Myanmar; and temperate East Asia to New Guinea. One species, Toxicodendron succedaneum, is naturalized in Brazil.
Several taxa published in other genera, including Rhus, belong in Toxicodendron but have not yet been transferred. Three sections are recognized within the genus: Simplicifolia, Toxicodendron, and Venenata (Gillis 1971;Gandhi 2021). The genus has been included in numerous phylogenetic studies, which have consistently found it to be monophyletic and quite distinct from Rhus (Miller et al. 2001;Yi et al. 2007).
One species in Amazonian Brazil, Colombia, and Peru (A. amazonicum) primarily in Amazonian tropical moist forest. Two species in tropical west and central Africa.
One species, Attilaea abalak, in tropical deciduous forests in primarily calcareous soils of Mexico and Guatemala. This species is very similar to Spondias purpurea, but can be distinguished by its often scandent habit and by its bicarpellate gynoecium, which differs from all other Anacardiaceae.
Two species in gallery forests and swamps from Honduras to northwest Ecuador (C. panamense) and in blackwaterflooded forests (igapó) in Amazonia (Campnosperma gummiferum (Benth.) Marchand). Eleven or more species in the Seychelles and Madagascar to Sri Lanka; southern Thailand and Malaysia, east to Micronesia and the Solomon Islands.
Five species in dry forests to open arid habitats: 1 endemic to southern Baja California; 2 in western Mexico; 1 in northern Colombia east to Guyana, Venezuela, and northern Brazil; 1 endemic to the Caatinga of Northeast Brazil.
Ten or more species in tropical moist forests, montane forests, gallery forests, campo rupestre, white sand campinas, and restinga from southern Mexico to southeastern Brazil, Bolivia, and Paraguay.
Tapirira lepidota differs from the other species in having 3-4(-5) styles, leaves and flowers covered in lepidote scales, and green fruit. Tapirira mexicana Marchand has a distinctly different endocarp from the other species in the genus and instead resembles that of Cyrtocarpa caatingae (Herrera et al. 2018). See Fig. 5 for illustrations of T. guianensis and Tapirira obtusa (Benth.) J.D.Mitch.