Introduction

For centuries, the diversity and wealth of Indonesian medicinal plants have been recognised worldwide. This was first noted by the French botanist Bontius (1658) in the list of Java medicinal plants compilation (de Padua et al. 1999) and the Portuguese botanist Georgius Everhardus Rumphius (1627–1702) in his work entitled Het Amboinsche kruidboek (Herbarium Amboinense) (Rumphius, 1741–1755; Veldkamp 2011). Medicinal plants are still widely used in Indonesian traditional medicine (Jamu), a tradition that is similar to Ayurveda in India and Traditional Chinese Medicine (TCM) in China (WHO 2009). These traditional Indonesian remedies remain widely used today, in urban as well as rural areas and among all social classes. About two-fifths of the national population use traditional medicine, and most traditional healers in Indonesia use Indonesian indigenous medicine (WHO 2009).

As a country rich in medicinal plants, it is difficult to quantify the exact number of plants in Indonesia, but it is estimated that 2,000 (Erdelen et al. 1999; WHO 2009) to 7,500 medicinal plants (Hamid and Sitepu 1990) are regularly used out of a total of around 30,000–40,000 plant species within the country (Ministry of National Development Planning 2016). There are high levels of endemicity and expected medicinal plant uniqueness in Indonesia is estimated to be at about 40%–50% of the total flora of each island, except Sumatera which has only 23% (Ministry of National Development Planning 2016).

Medicinal plants are valuable species not only for personal health care (de Padua et al. 1999) but also for their economic value as they are traded by local communities (Hawkins 2007). Indonesia's medicinal plants' economic value equates to as much as US$14.6 billion annually (Ministry of Environment The Republic of Indonesia 2013). Globally, the trade of medicinal plants in 2005 was more than US$3 billion (Jenkins et al. 2018) and this is estimated to grow to be worth US$5 trillion by 2050 (WHO 2009).

Indonesia is a vast country, with a land area of 1,919,440km2 spread over thousands of islands (Ministry of Environment and Forestry of Indonesia 2014). Conservation of Indonesian species is thus challenging and costly. Human population growth, land conversion, deforestation and climate change all contribute to medicinal plant loss, as well as overharvesting for medicinal trade (Voek 2004; Hawkins 2007; Ma et al. 2010). Hamilton (2004) argues that the loss of local knowledge regarding medicinal plants and their use is a global concern.

The economic value of medicinal plants in Indonesia, coupled with other threats and a lack of resources for their conservation, makes it urgent that active conservation programmes are put in place. An obvious initial step would be for some form of prioritisation of species and an assessment of the criteria which might be used. This has not been previously attempted in Indonesia, however a number of studies have been conducted elsewhere. Dhar et al. (2000) did undertake such an exercise in the Indian Himalayas prioritising consumers (using medicinal plants) and biologists (concerned about their conservation). The outcome was to prioritise conservation for species that are harvested in a destructive manner, that have restricted distribution and for which there are limited propagation techniques. van Andel et al. (2015) prioritised the medicinal plants in West Africa based on commercial demand, whether they are wild-harvested, and their occurrence in undisturbed vegetation types. Dery et al. (1999) conducted prioritisation in the Shinyanga Region of Tanzania involving local people with the necessary knowledge and scored their appraisal. Allen et al. (2014) prioritised European medicinal plants by selecting only native species.

Producing checklists that consist of the name of the species, the author details, inventories and additional information is essential to formulating the conservation strategies (Magos Brehm et al. 2017) and these form the groundwork for further action. Establishing priorities for conservation can be based on current conservation status, the threat of genetic conservation, and legislation (Maxted et al. 1997). Inventory is also needed to describe a country's species richness: an essential tool in conservation management (Magos Brehm et al. 2008). Considering these arguments, the economic value of medicinal plants in Indonesia and the need to prioritise conservation efforts, this project aims to analyse available data concerning Indonesian medicinal plants for active in situ and ex situ conservation and to provide a priority list of species.

Methods

The checklist of medicinal plants of Indonesia was compiled in Excel from relevant literature. The literature used was as follow:

  1. 1.

    Plant Resources of South-East Asia (PROSEA) book series, specifically: Medicinal and Poisonous Plants 1 (de Padua et al. 1999), Medicinal and Poisonous Plants 2 (van Valkenburg and Bunyapraphatsara 2002), Medicinal and Poisonous Plants 3 (Lemmens and Bunyapraphatsara 2003), and Spices (de Guzman and Siemonsma 1999). Only species distributed in Indonesia were selected. Poisonous plants were included but in lower number and only if they had a medicinal function (de Padua et al. 1999). Spice plant species were included as well because traditional people use them in medication (de Guzman and Siemonsma 1999).

  2. 2.

    Indonesian Medicinal Plant Indexes (Eisai 1986; 1995).

  3. 3.

    Atlas of Indonesian Medicinal Plants series 1–6 (Dalimartha 1999, 2000, 2003, 2006, 2008, 2009). Ganoderma lucidum (Curtis) P.Karst. (Ganodermataceae) was excluded from the list as it is fungi.

  4. 4.

    The Useful Plants of Indonesia (Heyne 1987). Only species with records of medicinal use was selected.

  5. 5.

    Rare Indonesian Medicinal Plants stated in IBSAP (Indonesia Biodiversity Strategy and Action Plan) based on Rifai et al. (1992) and Zuhud et al. (2001) (The National Development Planning Agency 2003). Usnea misaminensis (Vain.) Motyka, the Parmeliaceae family, was excluded as it belongs to the fungi kingdom rather than the plant kingdom.

The taxonomic names were checked against the online taxonomic name resolution service tool by checking "Constrain by higher taxonomy" under "Best match settings", which is effective for spelling errors and for merging all the synonyms into a single accepted name (Boyle et al. 2013). The steps are described in Fig. 1.

Fig. 1
figure 1

Flowchart of setting checklist of medicinal plants of Indonesia

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After the literature review, prioritising the checklist was done serially with the collected information, namely, (a) occurrence status, (b) rarity, (c) part of the plant harvested, (d) threat status, and (e) legislation (Fig. 2).

  1. a.

    Native status. Similarly to Allen et al. (2014), only species native to Indonesia were prioritised.

  2. b.

    Rarity. This criterion is based on the distribution of the species in Indonesia. Only medicinal plant species that are endemic, distributed on seven major areas in Indonesia (i.e. the main islands of Sumatera, Java, Kalimantan, Sulawesi, and Papua, and the area of the Lesser Sunda Islands and Maluku) regardless of their global distribution, and that have never been introduced elsewhere (with data obtained from literature and online through http://powo.science.kew.org/; POWO 2019) are listed as a priority. Plants never introduced elsewhere could describe their slow natural distribution and unavailability of propagation technique.

  3. c.

    Part of the plant harvested. The species for which the root or non-aerial parts such as tuber and rhizomes, complete bark, or whole plants are harvested were prioritised (as suggested by Dhar et al. 2000) as this is detrimental to the persistence of the species in the wild.

  4. d.

    Threat status. Since Indonesia does not have a national red list, the threat status at the global level for each species was retrieved from the IUCN Red List (https://www.iucnredlist.org/).

    The medicinal plant species that have been assessed as Critically Endangered (CR), Endangered (EN) and Vulnerable (VU) are considered a priority.

  5. e.

    Legislation. This criterion refers to the prioritisation of those species included in national or global legislation. This is very important because it depicts that the listed species need conservation and the government should be responsible to them (Magos Brehm et al. 2010). At a global level, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was used. Thus, the species threatened with extinction (listed in Appendix I) and the species which may be threatened with extinction if their trade is not closely monitored (listed in Appendix II of CITES (UNEP-WCMC (Comps.) 2014)) were prioritised. At the national level, the legislation related to medicinal plant conservation included the following:

    1. 1.

      Indonesian Government Regulation Act. 7 of 1999 regarding Natural Genetic Resources and Its Ecosystem.

    2. 2.

      Decree of Forestry Ministry No 57/MENHUT-II/2008 regarding Strategy Direction of National Species Conservation 2008–2018.

    3. 3.

      Decree of Environmental and Forestry Ministry No. P.20/MENLHK/SETJEN/KUM.1/6/2018 regarding the Protected Flora and Fauna Species.

    4. 4.

      Decree of Environmental and Forestry Ministry P.106/MENLHK/SETJEN/KUM.1/12/2018 revised decree of Environmental and Forestry Ministry P.92/MENLHK/SETJEN/KUM.1/8/2018 (replaced the Decree of Environmental and Forestry Ministry No. P.20/MENLHK/SETJEN/KUM.1/6/2018) regarding the Protected Flora and Fauna Species.

    5. 5.

      IBSAP (Indonesia Biodiversity Strategy and Action Plan) based on Rifai et al. (1992) and Zuhud et al. (2001) in The National Development Planning Agency (2003).

Fig. 2
figure 2

Flowchart of setting prioritisation of medicinal plants of Indonesia

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The listed plant species protected by Indonesian laws are classified as requiring protection due to their limited or small population, decreasing number of individuals and endemicity. The medicinal plants that were included in the CITES appendices I or II or any native medicinal plants that are listed in any national legislation were included in the priority list.

Due to the primary data for prioritisation, the checklist that consists of a scientific name and author are obtained online from POWO (2019). An inventory of priority medicinal plant species was compiled with their vernacular names, plant habit, used plant parts, uses, and DNA barcoding data (http://www.boldsystems.org/; Ratnasingham and Hebert 2007). Group plants that were selected based on criteria of limited distribution, destructive harvest, CITES, IUCN, and National legislation were showcased with a Venn diagram generated by Bioinformatics and Evolutionary Genomics (http://bioinformatics.psb.ugent.be/cgi-bin/liste/Venn/calculate_venn.htpl).

Ex situ conservation status information on whether the species has been collected or not was obtained from Indonesian botanic gardens through direct communication with Bogor Botanic Gardens, and by mining data online from Purwodadi Botanic Garden (http://www.krpurwodadi.lipi.go.id/koleksi/) and Cibodas Botanic Garden; http://sindata.krcibodas.lipi.go.id/Cibodas-Botanic-Gardens-Record/CBGR/) as well as from Genesys (https://www.genesys-pgr.org/).

Results

Establishing the checklist of Indonesian medicinal plants

Indonesia has a total of 5490 medicinal plant taxa, of which 5408 are identified species, and 82 can only be identified at the genus level. No further information can be identified for the 82 genus-level species; hence it cannot be concluded that they are new species. The 5408 Indonesian medicinal plant species are within 245 families and 1809 genera; 3312 are native (61.24%), 1754 (32.43%) are introduced, and 342 species (6.32%) are of unknown status. Most medicinal plants (8.84%) belong to the Fabaceae family (Fig. 3) since it is one of the biggest families of medicinal plants in the world (Willis 2017). There is estimated to be a total of 27,734 medicinal plant species around the world (MPNS 2020), meaning that Indonesia's medicinal species make up around 20% of the global population.

Fig. 3
figure 3

The families represented in the Indonesian Medicinal Plant Species Checklist. The species with a higher priority for conservation can be identified

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Prioritising and inventorying Indonesian medicinal plants

A total of 233 species of Indonesian medicinal plants, within 161 genera and 71 families, were prioritised for conservation (Table Appendix 1) according to the criteria discussed above (Fig. 3). The higher priority medicinal plant families belong to the Orchidaceae (34 species or 14.59%) and Dipterocarpaceae (26 species or 11.16%). Most of these are included in Appendix II of CITES or have been assessed as threatened in the IUCN Red List (Table Appendix 2). Some 127 out of the 233 priority species are known as medicinal plants worldwide (MPNS 2020), whereas 106 species are used as commercial timber (Dipterocarpaceae), ornamental plants (Orchidaceae) and sources of fibre (Nepenthaceae).

Some 96 out of 233 (41.20%) major priority medicinal plants are distributed in one major area/island and harvested in a destructive manner. Some species are included in the priority list solely based on the IUCN threatened list (2), CITES Appendix II list (25), and in Indonesian legislation (11) (Fig. 4).

Fig. 4
figure 4

Venn diagram of priority medicinal plant species grouped into prioritisation criteria

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The rest of the species in the CITES Appendices may represent global demand, and da Silva and Conde (2019) have used it for their own prioritisation. Moreover, the CITES Appendices are managed based on trading data and are very important in Indonesia. Throughout Asia, as Ma et al. argue (2010), the illegal trade in medicinal plants like orchids cause losses in plant diversity. However, it is difficult to assess this adequately in Indonesia due to its size and large remote areas.

Most of the medicinal plants that can be classed as priority (77.25%) are harvested destructively either by removing the rooting parts (root, rhizome, or tuber), bark, or harvesting the entire plant. The remaining plants (14.59%) are harvested through other parts such as their leaves, sap, stems, fruits, or flowers. Some 8.15% of the priority species have no information regarding how they are harvested, as their harvesting methods were not necessarily designed solely for medicinal use. Harvesting non-aerial parts of the plant (root, rhizome and tuber, bark and rhizome) makes the plants highly susceptible to failure or can directly kill the plants. Other parts of the plant, such as leaves, flowers, and seeds, are excluded from the prioritisation criteria, although they can also affect the plant's vigour and fitness. Nevertheless, the harvesting of root and bark might affect mostly shrubs and trees, whereas the collection of seed affects mainly annuals and biannuals (Schippmann and Cunningham 2002).

In term of the habit types of priority medicinal species, the majority type consists of trees (32.62%), shrubs (27.03%), herbs (24.03%), lianas (6.44%), climbers (6.01%), tree like-palms (3.00%), and holoparasite (0.86%). Some 97 of the 233 priority species have been identified through DNA barcoding and provided online (http://www.boldsystems.org/; Ratnasingham and Hebert 2007). The taxonomic identification via DNA barcoding is of high importance for conservation. Since plant phenotypic characteristics are affected by physiology and environmental factors (Chen et al. 2010 and Techen et al. 2014) it may become difficult to identify certain species. Thus, for conservation purposes, consistent results of DNA barcoding can help to prevent deception and theft of protected and commercial species (Kress et al. 2014 and Mishra et al. 2016). Furthermore, it also protects the rights of consumers to use authentic plant species for their medicines, as the barcoding can be conducted on both fresh and dried plants (Dick and Webb 2012) as well as on market products (Eurlings et al. and Newmaster et al. 2013).

Regarding their distribution, 53 priority species are endemic to Indonesia (see Table 1), 179 species are distributed in both Asia and Australia, and one species (Dodonaea viscosa Jacq. subsp. angustifolia (L.f.) J.G.West) is distributed worldwide. Sundaland and Wallacea, with 93 and 24 endemic medicinal plant species respectively, are included in the hotspot areas identified by Myers et al. (2000) and Mittermeier et al. (2011) as having significant endemism and threats. The number of native medicinal plants in Indonesia showcases how rich Indonesia's biodiversity is, a point also noted by Vavilov (1935) who identified it as a centre of origin/diversity of cultivated plants.

Table 1 Level of endemism of priority medicinal plant species within Indonesia
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Indonesian people in villages often intensively use a traditional medicinal plant that they collect from the wild and plant in their home gardens (Astutik et al. 2019). Nevertheless, we could not identify the priority species data regarding their collection and planting locally as medicinal plants. In addition, ex situ conservation institutions have been actively collecting priority medicinal plants. More than half of the 233 species have been planted in nurseries or botanical gardens either nationally or internationally. Some 137 priority species are cultivated in the Indonesian Botanic Garden–Indonesian Institutes of Sciences and one species [Phyllodium elegans (Lour.) Desv.] can be found at the International Livestock Research Institute (ILRI) (Ethiopia) with Forages as its common name. Despite being distributed in more than two islands/areas, 107 priority species that are threatened globally have been listed in national legislation. Likewise, Borassus flabellifer L. (Arecaceae) and Dalbergia latifolia Roxb. (Fabaceae) are threatened but have been introduced to other parts of Indonesia as well as to other countries.

Discussion

Checklist of Indonesian medicinal plants

As Paton et al. (2016) have argued, plant species names serve as "a key to communicating and managing information about plants". Creating a national checklist of Indonesian medicinal plant species, and annotating with additional data to allow for prioritisation, is essential groundwork for conservation. As the information is currently located in different sources and is arguably incomplete, there are many areas of literature and numerous journals that discuss medicinal plants that need to be collected and reviewed. The Medicinal Plant Names Services (MPNS 2020) can be useful to access the global information for medicinal plants and to build up understanding amongst both scientific and non-scientific users. Many journals report ethnobotanical studies of Indonesian people that are rich in ethnicity, but the MPNS to date has little information regarding Indonesia plants. For this project, the literature that is estimated to have a complete species list of Indonesian medicinal plants was selected for further study.

Using the TRNS tool (Taxonomic Name Resolution Service; Boyle et al. 2013) to help with the taxonomical check name was helpful for this research but some issues were unable to be resolved. Homonyms and ambiguous names needed to be checked manually. Some plant names are Rumphius-related names such as Sampacea montana Rumph. and Arbor spiculorum aeruginea Rumph. that are pre-binomial names, not binomial. This is because Rumphius works had not been recorded in Species Plantarum, the starting point of binomial names by Linnaeus (1753) (Raven and Margulis 2009) and was resolved by available synonyms in the available literature (Eisai 1986). The value of this "resolution" is also constrained by the quality of the underlying taxonomic resources available. To resolve the taxonomic status would allow for better tracking of the plant to the names employed in original publications, enabling them to be matched to modern comprehensive nomenclatural and taxonomic datasets.

Allkin (2014) and Rivera et al. (2014) describe the frequent use of ambiguous names and even misleading names that exist in the literature, scientific journals, and international legislation in terms of medicinal plant names. Some 3,445 names out of 9,178 Latin names from 308 scientific articles were incorrect, as identified by Rivera et al. (2014). This might happen because, in certain circumstances more than one name can refer to a plant, while on the other hand one name can refer to more than one plant, or the name can keep changing (Allkin 2014). Dauncey et al. (2016) suggested authors use the proper and unambiguous scientific plant(s) names of medicinal plants or their products before publishing their articles in order to maintain scientific integrity. The confusion concerning the identity of plants employed is made even more complex because of the widespread use in health legislation of common, trade, product and pharmaceutical names (the latter also written in Latin) which are inherently ambiguous (Allkin 2014). Labelling plant materials correctly and unambiguously is a key step in researching medicinal plant use (Allkin and Patmore 2018).

The checklist resulting from this study might not be perfect, and can only reduce the pitfall of medicinal scientific names, that is synonym names and homonyms (Allkin and Patmore 2018). However, it can also be a reasonable basis for future research and coordination in discussing whole species to conserve, considering many medicinal plants can be found in Indonesia. As the ethnobotanical knowledge, especially regarding new medicinal plants, is still increasing this study serves as a foundation for future work.

Priority of Indonesian medicinal plants, their current conservation and conservation planning.

Prioritisation has been done for some plant taxa in Indonesia, but this research was not specifically for medicinal plants. Studies include those by Mogea (2001), Risna et al. (2010), and Hamidi et al. (2019). Mogea et al. (2001) listed 200 rare plant species in Indonesia and 29 priority medicinal plants are included in his list, namely Anaxagorea javanica Blume (Annonaceae), Pimpinella pruatjan Molk. (Apiaceae), Alstonia scholaris (L.) R.Br., Alyxia halmaheirae Miq., A. reinwardtii Blume, Rauvolfia serpentina (L.) Benth. ex Kurz, Urceola laevigata (Juss.) D.J.Middleton & Livsh., Voacanga grandifolia (Miq.) Rolfe (Apocynaceae), Caryota no Becc., Phoenix paludosa Roxb. (Arecaceae), Oroxylum indicum (L.) Kurz (Bignoniaceae), Cibotium barometz (L.) J.Sm. (Cibotiaceae), Shorea palembanica Miq. (Dipterocarpaceae), Euchresta horsfieldii (Lesch.) Benn., Koompassia malaccensis Maingay, Parkia intermedia Hassk., P. timoriana (DC.) Merr. (Fabaceae), Scutellaria javanica Jungh. (Lamiaceae), Cinnamomum culilaban (L.) J.Presl, C. sintoc Blume, Cryptocarya massoy (Oken) Kosterm. (Lauraceae), Strychnos ignatii Bergius, S. lucida R.Br. (Loganiaceae), Vanda miniata (Lindl.) L.M.Gardiner (Orchidaceae), Kadsura scandens (Blume) Blume (Schisandraceae), Symplocos odoratissima (Blume) Choisy ex Zoll (Symplocaceae), Aquilaria hirta Ridl. (Thymelaeaceae), Amomum sumatranum (Valeton) Skornick. & Hlavatá, and Curcuma petiolata Roxb. (Zingiberaceae). Risna et al. (2010) prioritised the family of Arecaceae, Cyatheceae, Nepenthaceae, and Orchidaceae as a taxa unit considering the nature of each plant and the natural habitat, with the result of ex situ conservation recommendations on some taxa. Three priority medicinal plants are in line with other results and are Nepenthes reinwardtiana Miq., Johannesteijsmannia altifrons (Rchb.f. & Zoll.) H.E. Moore, and Nepenthes ampullaria. Anisoptera costata Korth. (Dipterocarpaceae), Castanopsis argentea (Blume) A.DC. (Fagaceae), and Eusideroxylon zwageri Teijsm. & Binn.(Lauraceae) are also included in priority plant taxa that need to be conserved in Indonesia (Hamidi et al. 2019). Moreover, the Ministry of Agriculture published Decree No. 511 Year 2006, which was first revised with Decree No. 141 Year 2019, and finally revised with Decree No. 104 Year 2020, which lists horticultural plants grown in Indonesia. This includes a number of medicinal plants that are produced and processed for market. Three priority species, Curcuma aeruginosa Roxb., Lunasia amara Blanco, and Rauvolfia serpentina (L.) Benth. ex Kurz, have already been included in horticulture plant priority lists since 2006. Thus, some priority Indonesian medicinal plants identified in this study have been confirmed as priority species by other studies. These depict the need for a priority conservation list for sustainable use.

This priority list can be used to help formulate in situ and ex situ conservation plans through the National Priority Program included in the Mid-Term National Development Plans of Indonesia, in line with the Convention on Biological Diversity regarding the conservation of biodiversity and its sustainable use (CBD 2010). The priority list also helps to achieve the Global Strategy for Plant Conservation 2011–2020 objectives and its targets: objective I ("Plant diversity is well understood documented and recognised"), II ("Plant diversity is urgently and effectively conserved"), III ("Plant diversity is used in a sustainable and equitable manner"), IV ("Education and awareness about plant diversity, its role in sustainable livelihoods and importance for all life on earth is promoted"), and V ("The capacities and public engagement necessary to implement the strategy have been developed").

The stakeholders involved in the conservation and use of medicinal plants, particularly in Indonesia, can use the priority list of medicinal plants developed here as a basis for coordinated and systematic active conservation work. It is clear that conservation efforts on Indonesian medicinal plants have already been made, but the information and network of stakeholders either does not currently exist or is difficult to access, hence the need to make it more widespread and strengthened. This network will find what has and what has not been done regarding conservation so that active conservation may utilise its limited resources on the conserving those Indonesian medicinal plants that most need it.

Conclusion

This study has identified a total of 5490 medicinal plant species of which 233 are a priority for conservation. Not all priority species are well-known as medicinal plants, such as those that belong to Dipterocarpaceae (mostly timber plants) and Orchidaceae (mostly ornamental plants). An inventory of priority medicinal species was developed, and it is hoped that this can be used to help the medicinal plant's stakeholders, mainly comprising researchers and government officials working on the systematic conservation of priority Indonesian medicinal plants. This priority list can be used to help formulate in situ and ex situ conservation plans at regional and national levels. Furthermore, dissemination to a wider public will help in raising knowledge and awareness of medicinal plants, which is essential towards the conservation of these valuable resources.