Notes on Ipomoea L. (Convolvulaceae) in Cuba and neighbouring islands with a checklist of species found in Cuba

Summary An updated checklist of species of Ipomoea L. found in Cuba is presented with analysis of the different elements represented. I. alterniflora Griseb. is defined broadly to include I. obtusata Griseb. and I. excisa Urb. and its differences from the little-known I. cubensis (House) Urb. are discussed. I. calophylla C. Wright ex Griseb. is reinstated as the correct name for the species generally known as I. lacteola House. I. praecox C. Wright is recognised as a distinct species from I. argentifolia A. Rich. and images are provided to help distinguish the two species. I. flavopurpurea Urb. and I. dajabonensis Alain are shown to be conspecific with I. longeramosa Choisy, whose disjunct distribution is mapped and discussed. The little-known I. montecristina Hadač is described and illustrated and the cited collections show it to be locally common in the Guantánamo region. I. microdonta J. R. I. Wood & Scotland is described as new from Camagüey in central Cuba. Eight species endemic to Cuba collected by Ekman and described by Urban in 1924 – 25 are evaluated but only two, I. balioclada Urb. and I. erosa Urb., are deemed to warrant recognition as distinct endemic species. The origin and typification of I. horsfalliae Hook. are discussed and an epitype designated. Cultivated plants named I. horsfalliae occur in many tropical countries including Cuba but their extreme variation suggests hybrid origin. Four species from Jamaica, I. rubella House, I. lineolata Urb., I. carmesina Proctor and the Jamaican plant called I. horsfalliae are treated as synonyms of a variable I. lineolata, which is endemic to the island. I. saxicola Proctor is treated as var. saxicola J. R. I. Wood & Scotland of I. ternata Jacq. I. cyanantha Griseb. is treated as a synonym of I. lindenii M. Martens & Galeotti. Lectotypes are designated for I. cyanantha, I. lindenii, I. praecox, I. punctata C. Wright, I. geranioides Meisn. and I. grisebachii Urb.


Introduction
There are approximately 430 species of Ipomoea found in the New World, an estimate based on the list published by Austin & Huáman (1996), on various more recent publications and on our own on-going research as part of the Ipomoea "Foundation Monograph" project (Wood et al. 2015(Wood et al. , 2017Wood & Scotland 2017a, 2017b. As a generalisation it can be stated that the genus is more or less restricted to regions with a tropical or subtropical climate and very few species occur at higher latitudes than 30°. However, species diversity is far from uniform. Few species grow above 2000 m and there are remarkably few in the more humid lowland forest areas, particularly the Amazon basin (Wood & Scotland 2017b). The lack of diversity in Colombia appears genuine and is remarkable given the variety of habitats and climates in that country. Diversity is particularly great around the 20 -25°l atitudes in Mexico and in the southern hemi-sphere in southern Bolivia, northern Argentina, Paraguay and south-central Brazil (Wood & Scotland 2017a, b).
Another interesting feature is the presence of around 20 -25 very widespread species in nearly every tropical country both in the Old and New Worlds. These species constitute 50% or more of the Ipomoea flora in countries where the genus is less diverse but usually amount to around 20% of the total even in the countries with the most diverse floras. These very widespread species are often of imprecise origin, grow in disturbed or maritime habitats and are sometimes apparently recent introductions or escapes from cultivation.
Island endemism is also interesting. In the New World there are single endemics in the Galapagos Islands (Ipomoea habeliana Oliv.), Hawaii (I. tuboides O. Deg. & Ooststr.), St Eustatius (I. sphenophylla Urb.) and Puerto Rico (I. steudelii Millsp.). None of the other smaller islands has a single endemic species. However, high levels of endemism are reported from larger islands, that is Jamaica (4 species), the island of Hispaniola (7 or 8 species) and Cuba (15 species) by our conservative estimates. The level of endemism in Cuba is remarkable and only rivalled by the large continental countries of Mexico, Bolivia and Brazil. Most, but not all, of the endemic species of Cuba, Hispaniola and Jamaica as well as several species found in other Caribbean islands belong to a single clade of Ipomoea characterised by having coriaceous, concave, equal or only slightly unequal sepals, referred to below as the "coriaceous sepal clade". There is a clear radiation of this clade in the islands of this region, but it is represented by only a few species in continental Central America and Mexico. The clade also boasts a number of unusual features uncommonly or never found elsewhere in Ipomoea; several species are remarkable for developing leaves on brachyblasts (most obviously I. tenuifolia (Vahl) Urb., I. steudelii Millsp. and I. eggersiana Peter but also I. microdonta J. R. I. Wood & Scotland described as new below), all four, perhaps coincidentally, remarkable for their small leaves. Others show a remarkable plasticity in leaf form, most notably I. microdactyla Griseb. and I. clausa Rudolphi ex Ledeb., but this is also a feature of the Cuban endemic I. alterniflora Griseb. discussed below. Deeply lobed corollas occur in some species (especially in I. repanda Jacq.) while contrasting corolla shapes as a result of different pollination syndromes (I. eggersiana and I. steudelii) are also noteworthy. These unusual features sometimes aid species delimitation but in other cases lead to uncertainty, most notably in the case of I. horsfalliae Hook. discussed below.
We consider there are 50 species of Ipomoea definitely occurring in Cuba with another nine excluded for one reason or another. These are listed below in six informal categories: Introduced species present in cultivation, which may or may not have escaped (6) Widespread, often weedy, species found in both the neotropics and palaeotropics, which are well established and which in several cases may be native (probably introduced species are indicated by asterisks) (14): Ipomoea alba L., *I. aquatica Forssk., and HAJB) and one in Sweden (S), where Ekman's specimens are held. We have seen many of Wright's collections at HAC and at K and we have studied the particularly rich holdings of Jamaican collections at BM. Specimens have been examined using binocular dissecting microscopes to observe floral and indumentum details. We have also made considerable use of digital images, principally of types which are available through JSTOR (www.jstor.org/) but have also received images of important individual specimens held at IJ and LE.
NOTE ON SPECIMEN NUMBERS. Most specimens at HAJB are without collection numbers and are stored under accession numbers. In order to indicate this, specimens, principally from HAJB but occasionally at HAC, are cited by the herbarium acronym followed by the accession number.
Numbers in square brackets after Wright's original numbers are those by which Wright's collections are cited by Sauvalle (1870).
As understood here Ipomoea alterniflora is a variable species characterised by its glabrous stem, leaves and corolla. The leaves are usually ovate, cordate and shortly acuminate to an obtuse apex but are sometimes lobed as in the possible isotypes in HAC and NY. The inflorescence consists of lax, few-to many-flowered cymes. The sepals are subequal to slightly unequal, ovate, coriaceous, concave and glabrous. The corolla appears to be always narrowly funnel-shaped with included anthers. The corolla colour in the holotype is whitish-green ("albida" according to Grisebach) and this is clearly the same in the GH and HAC isotypes but the NY isotype is more darkly coloured and could be red. The seeds are pilose on the margins with long whitish hairs.
The most variable aspects of this species lie in the leaf shape. In the type of Ipomoea obtusata the leaves are ovate-elliptic with a rounded to cuneate base and obtuse apex. In the type of I. excisa the leaves are ovate but the apex is retuse. Although the extreme forms are rather distinct, there are many specimens which connect these with more common forms typified by Wright 3099 and the type of I. alterniflora. It is worth noting that almost from the time of their original descriptions by Grisebach, Wright (in Sauvalle 1870: 45) regarded I. obtusata and its varieties as synonyms of I. alterniflora but this was ignored by later authors.
Ipomoea alterniflora is endemic to western Cuba from where all collections come. It appears to be a plant of forest relics.
Although Urban (1925: 427) treated Wright 3099, Wright 12563 and Ekman 13494 as Ipomoea cubensis, this species is quite distinct as is clearly seen in the image of the type available through JSTOR and in the illustration in the Bull. Torrey Bot. Club (House 1908a: plate 2, at end). These both show a plant with deeply laciniate leaves, a broadly funnel-shaped corolla and strongly exserted stamens. We have seen no material that matches this very convincingly but H. Manitz (HAJB51284) from "Soroa cerca del Orquideario", Pinar del Río, in western Cuba could well be this species. However, a search needs to be made in the gorge of the Yamurí River above Matanzas where the type was collected to relocate authentic examples of this species. In passing it should be noted that it is just possible that I. cubensis represents an example of extreme variability in I. alterniflora, a feature of the "coriaceous sepal" clade discussed in the introduction above and under I. horsfalliae below.
At Stockholm (S) there is a set of interesting specimens from the early 19th century which match the type of Ipomoea obtusata; these come from the Swartz herbarium and at least one of these was apparently collected by Forrström. According to Álvarez Conde (1958), Swartz visited Cuba so he, rather than Forrström, may have made these collections.
Type: based on I. calophylla C. Wright ex Griseb.

Ipomoea praecox
Most of Charles (Carlos) Wright's new species from Cuba were published by Grisebach (1866) in the Catalogus plantarum cubensium. Two species of Ipomoea, however, were described by Wright and published by Sauvalle (1870) in the Anales de la Academia de Ciencias Medicas, Fisicas y Naturales de la Habana. One of these was Ipomoea praecox, a species normally treated as a synonym of I. argentifolia. Examination of the type specimen and a series of collections in the Cuban herbaria shows that these two species are distinct. This was presumably also Wright's opinion as he had already collected and recognised I. argentifolia (Sauvalle 1870). I. praecox differs from I. argentifolia in being leafless when flowering, in having the flowers arranged in dense, very shortly pedunculate, axillary subracemose cymes with up to six flowers, smaller, broadly ovate to suborbicular sepals 7 -8 × 5 -7 mm, which are hirsute only in the lower part and often reddish ( Fig. 1). In contrast I. argentifolia has fully developed leaves at anthesis, the flowers arise on short, leafy axillary branchlets and the sepals are elliptic, longer, c. 10 -11 × 6 -7 mm, silvery in colour, the whole abaxial surface being covered in silvery hairs (Fig. 2). These differences are all clearly visible on the images of the types of the two species, which are available on JSTOR. Additionally the two species appear to be distributed differently. I. argentifolia is found on the Isla de Juventud (Pinos) off the west coast of Cuba but also occurs in the east of Cuba in the Sierra Maestra and Sierra de Nipe. In contrast, I. praecox is a plant of the Pinar del Río region.

Ipomoea punctata
Ipomoea punctata was a second species described by Wright (1870) after the publication of Grisebach's Catalogus Plantarum Cubensium (1866). Although the epithet punctata had already been used by Poiret it was in fact quite appropriate for this species as the abaxial surface of the younger leaves is clearly punctate. Within the Cuban context, the species is very distinct, being annual, the corolla cream with a purple centre (hence Urban's nomen novum flavopurpurea), the sepals with acute, strongly mucronate tips and the seeds shortly tomentellous and very different from the long pilose seeds of other Cuban endemics. We have never had material of this species available for sequencing so had not considered the possibility that it might be conspecific with a South American species until we noticed that Ekman 1876 (S) from Santa Clara in Cuba had been identified as I. longeramosa Choisy by O'Donell. Examination of Brazilian material of I. longeramosa showed that it matched the Cuban plant exactly and the leaves even have the same punctate lower surface which Wright observed. We have also been able to review an isotype of I. dajabonensis at Berlin through JSTOR and this is clearly also conspecific, something confirmed by the illustration in La Flora Hispaniola (Liogier 1994: 80 possibilities of its occurrence elsewhere, particularly in the north of Colombia cannot be discounted. The wide distribution but apparent rarity everywhere except in parts of NE Brazil is remarkable. This rather odd distribution pattern is also shared to some extent by two other species that occur in Cuba. One, Ipomoea subrevoluta Choisy, is a widespread but never very common South American species of stream sides in savanna which has been known in Cuba from the Isla de Pinos (Juventud) since Wright's time. It occurs in scattered populations in Bolivia, Brazil, Colombia, Guyana, French Guiana, Paraguay, Peru, Trinidad and Venezuela, but is often only known from one or two locations in each country. The other is Ipomoea heptaphylla Sweet (= I. wrightii A. Gray). This is widespread in tropical and subtropical America from Argentina to the United States but likewise occurs in scattered populations and is generally uncommon.

RECOGNITION.
Although originally identified as Ipomoea cavanillesii Roem. & Schult., a synonym of I. cairica (L.) Sweet, this species differs in many significant ways including the absence of stipule-like outgrowths at the base of the petiole, the tiny, minutely toothed leaves borne on short brachyblasts, the small corolla and the seeds with long marginal hairs. These characters, combined with the subequal, glabrous, rather rigid sepals, suggest it belongs to the "coriaceous sepal" clade.

Urban's Cuban Ipomoeas
Urban (1924,1925)   the main Cuban herbaria (HAC, HAJB). We have evaluated these species as follows: Ipomoea arnoldsonii Urb. (Urban 1925: 424) This species is only known from the type collection (Ekman 18029) from Pinar del Río. It is a good flowering specimen and it seemed strange that it had not been recollected as it comes from the well-known area of Viñales in Pinar del Río. Examination of the type and the sequence of Ekman's collections at Stockholm shows that Ipomoea arnoldsonii is a nearly glabrous form of I. fuchsioides with only a few hairs on the young stems and leaves. It was collected along with Ekman 18031 which is perfectly typical I. fuchsioides and shares exactly the same collection details. It seems that Ekman must have selected a nearly glabrous plant from a colony of I. fuchsioides and collected it under a separate number. We, therefore, regard it as a synonym of I. fuchsioides.
Ipomoea balioclada Urb. (Urban 1924: 245) This is still only known from the type (Ekman 8080) and two further collections, Ekman 8749 and 14805, the latter the only collection with flowers. No recent collections of this species were found in either HAC or HAJB. Despite this and O'Donell's tentative determination of it as Ipomoea alterniflora we accept I. balioclada as a good species. It is superficially identical to red-flowered forms of I. alterniflora but differs in the presence of conspicuous black glands on the stems. Geographically it is a species of extreme eastern Cuba from the Sierra Maestra above Daiquirí, 14 km E of Santiago de Cuba, a long distance from the known populations of Ipomoea alterniflora.
Ipomoea beyeriana Urb. (Urban 1924: 425) This species is only known from the type (Ekman 18234) which is in fruit. O'Donell annotated the specimen with doubt as Ipomoea alterniflora. We think it is much more likely to be an entire-leaved form of I. microdactyla Griseb., based on the leaf shape and the reddish sepals. Urban (1925: 425) suggested an affinity with I. fuchsioides and it is not unlike I. fuchsioides var. glabrata Griseb., which we regard as a form of I. microdactyla. It is an even better match for Wright 3102, the type of Exogonium microdactylum var. integrifolium House, which we also regard as a synonym of I. microdactyla. I. beyeriana was collected in Pinar del Río where I. microdactyla is not uncommon.
Ipomoea erosa Urb. (Urban 1925: 425). This is only known from the type specimen collected in the Sierra de Nipe in the extreme east of Cuba. We recognise this as a distinct endemic species distinguished by the greenish-white corolla and hirsute, mostly denticulate leaves. It should be relatively easily recognisable like Ipomoea balioclada even when sterile because of the distinctive leaves. No further specimen, however, has been seen despite search in the Cuban herbaria and collections of other species from the Sierra de Nipe.
Ipomoea excisa Urb. (Urban 1924: 246) We consider this to be a not very distinct form of Ipomoea alterniflora with retuse leaves and have treated it as a synonym of that species above.
Ipomoea lindmannii Urb. (Urban 1924: 248). This sterile shoot (Ekman 7508) was collected at Mir in eastern Cuba. No flowering or fruiting material has ever been found and it cannot even be certain that it is a species of Ipomoea. It is remarkable, however, for the shiny, silvery abaxial surface of the ovate-deltoid, cordate leaves. At HAC there is a similar sterile specimen (Alberto Alonso 26585) but this comes from Guanahacabibes, Pinar del Río, far from the type locality of I. lindmannii. Until flowering material can be found to confirm the identity of these plants, I. lindmannii should be treated as a dubious species of Ipomoea.
Ipomoea perichnoa Urb. (Urban 1925: 426) Collected from the Guanahacabibes peninsula in Pinar del Río, the type of this species (Ekman 18781) is a fruiting specimen with densely lanate seeds, the hairs covering the whole surface of the seeds. Apart from the unusual seeds there is nothing in the type specimen to suggest it is distinct from Ipomoea jalapa (L.) Pursh, the species with which Ekman compared it (under the name I. calantha Griseb.). Two flowering specimens (Ekman 13521 and 18176) from different localities in Pinar del Río and Havana were cited as probably conspecific but these cannot be distinguished from I. jalapa. We have seen hardly any specimens of I. jalapa with seeds so it is very difficult to be certain that the seeds of Ekman 18781 lie outside the range of variation found in I. jalapa. They are similar to the seeds of the closely related I. macrorhiza Michx., which is endemic to the United States but unknown from Cuba so it seems quite likely that similar seeds are found in I. jalapa. I. perichnoa, therefore, remains an uncertain species although it is probably a form of I. jalapa, a species known from Pinar del Río and Habana in Cuba (Sauget & Liogier 1957: 240).
Ipomoea robusta Urb. (Urban 1925: 424). This is based on a relatively unremarkable sterile shoot (Ekman 18220) collected in Pinar del Río. While this could be a species of Ipomoea, it too should be treated as a dubious species unless fertile matching material can be found.

Mrs Horsfall's Ipomoea
Amongst the cultivated species of Ipomoea occurring in Cuba is Ipomoea horsfalliae Hook. This is grown in many tropical countries under various names including "briggsii" (after Sir Thomas Graham Briggs), "Lady Doorly's Morning Glory", "Cardinal Creeper" and "Prince Kuhio Vine" (Hawaii), the various names representing local names, cultivars or explanations of its supposed origins. It is a woody liana with digitate leaves composed of (3 -) 5 (-7) sessile, glabrous leaflets and large branched inflorescences of very attractive pink flowers, viewable on numerous internet sites. The sepals are coriaceous, concave and glabrous, equal or somewhat unequal in size, thus placing I. horsfalliae in the "coriaceous sepal" clade with I. mauritiana Jacq. and many Caribbean species, something confirmed by our molecular studies. Ipomoea horsfalliae shows many kinds of variation. The leaflets are usually sessile (as in the type) but in many forms the leaves are merely lobed (Fig. 5A). In some specimens the corolla is deeply lobed but in others it is much more shallowly lobed. This variation can be appreciated by viewing images on the internet. Powell (1979: 268) noted that one such specimen, Fairchild 2768 from St Lucia, appeared to be intermediate between I. horsfalliae and I. repanda and was presumably a hybrid between the two. There was "progression in leaf-lobing from 3 to weakly 7-lobed. Each flower had a slightly curved cylindrical corolla tube… with the limb ... lobed for its entire length, the pistil and stamens exserted." She suggested that "Herbarium material often inaccurately (sic) labelled 'Ipomoea horsfalliae (Cult)' and collected throughout the tropics is mostly of similar hybrid material with lobed leaves and narrow-tubed flowers, scarcely to deeply lobed. The cultivated var. briggsii is perhaps this hybrid." The existence of hybrids has also been mentioned by Acevedo-Rodríguez (2005: 167). The apparent rarity of fruits in cultivated plants together with extreme variation in corolla characters tends to support the view that cultivated I. horsfalliae is of hybrid origin. It seems that propagation is mostly from cuttings and very rarely from seeds.
The origin of Ipomoea horsfalliae has been uncertain from the beginning. Hooker (1834) reported that the seeds were thought to come "from either Africa or from the East Indies" and as recently as 2012, Acevedo-Rodríguez & Strong (2012: 241) suggested it was South American. However, a Caribbean origin has usually been proposed and this is supported by its inclusion in a clade of mostly Caribbean species with coriaceous sepals. Urban (1903) suggested it might have originated in Puerto Rico, where it grows "in moist forests of the Cordillera Central and in the zone of mogotes" but was treated as "possibly exotic and naturalized" (Acevedo-Rodríguez 2005: 167). However, the only place where plants similar to I. horsfalliae occur as definitely native species is Jamaica (Adams 1972;Austin 1980). Examination of a good number of specimens of apparently naturally occurring plants from Jamaica shows that these consistently differ from I. horsfalliae collected elsewhere in their petiolate leaflets. We were unable to find any Jamaican specimen that matched the numerous cultivated examples of I. horsfalliae and we do not think they represent the same taxon, even though the cultivated I. horsfalliae may well have arisen as a result of hybridisation involving the Jamaican plant. There is a clear need for more intensive study making use of DNA sequencing to resolve this issue. In the meantime we treat the cultivated plant as a distinct taxon of unknown but probably hybrid origin, nowhere occurring certainly as a native species.
Ipomoea horsfalliae Hook. (Hooker 1834: t. 3315 No type was preserved so the illustration by Mrs Horsfall in Curtis' Botanical Magazine is here chosen as the lectotype. This image is slightly ambiguous about the fusion of leaflets at their base and is relatively few-flowered with inflorescences of 3 -7 flowers. The exsertion of the stamens is slightly different in the two corollas, being distinctly exserted in one case but held at the mouth in the other. In order to clarify the characteristics of this species we have selected the specimen at Kew (K000612699) as an epitype (Fig. 6). This specimen originates from Hooker's herbarium and is dated 1858, so, although it is not the original material used by Mrs Horsfall, it may well be derived from the same plant. In any case it matches the original painting well and no more suitable specimen is available. ETYMOLOGY. Unusually, Ipomoea horsfalliae was named for the artist, Mrs Horsfall, who prepared the painting from a plant cultivated by her husband's "very skilful gardener Henry Evans at Everton…"

A Jamaican complex
Although Ipomoea horsfalliae, as defined above, has not been recorded from Jamaica, the situation on the island is somewhat complicated by the presence of four closely related taxa, all clearly close to I. horsfalliae. Two of these have leaves divided into five leaflets, I. horsfalliae sensu Adams (1972) and I. rubella House, which Adams distinguished by differences in  corolla size and the relative length of the sepals. Examination of a range of specimens show that these differences do not hold up and, as there exist intermediates, noted also by Adams, the two species cannot be separated satisfactorily. Two further species endemic to Jamaica differ only in having leaves divided into three leaflets. These are I. lineolata Urb. and I. carmesina Proctor. I. lineolata is reported to be relatively slender with few-flowered cymes but this is not apparent from herbarium specimens. I. carmesina is known only from the type and differs from I. lineolata in its many-flowered cymes, a characteristic placing it somewhat intermediate with the plant Adams called I. horsfalliae. None of the four species discussed here show any marked geographical or ecological pattern in their distribution in Jamaica and there seems no reason to treat them as separate species and so we treat them as single species under the oldest accepted name: subsequent students of the genus. Formal synonymy and lectotypification are set out below: Ipomoea lindenii M. Martens & Galeotti (1845: 264 LECTOTYPIFICATIONS. Grisebach cited collections by Purdie and Wullschlägel after the description of Ipomoea cyanantha. We have designated the Purdie collection at Kew as lectotype as it is annotated by Grisebach and is the source of the quotation "fine blue" to describe the corolla colour quoted by Grisebach in the protologue and which was presumably the inspiration for the specific epithet "cyanantha". We have also taken the opportunity to lectotypify I. lindenii. Martens & Galeotti cited two types, Galeotti 1360 and Linden 301 from Zacuapan in Mexico. We have selected Galeotti 1360 (BR00006973308) as lectotype as Linden 301 is not represented at Brussels and Galeotti is likely to have based the description on his own collection. There are isolectotypes at BR, G, K and P, the Kew specimen mounted on the lower half of a sheet on which Linden 301 is also mounted. The lectotype has been incorrectly annotated as the holotype. As a result of the decisions in this paper the number of Ipomoea species endemic to Jamaica is reduced to four: I. lineolata, I. ternata Jacq., I. jamaicensis G. Don and I. tenuifolia.