ARTICLE HIGHLIGHTS
Orchidaceae is the largest family of flowering plants facing threats due to habitat destruction, forest fires, over collection etc.
Alkaloids, carbohydrates, flavonoids, glycosides, and other phytochemicals found in orchids play an important role in pharmaceutical and cosmetology sector.
There is an immediate need by public, private sectors and research universities/institutes to conserve these precious species which can be made possible via public awareness programs and various conservation techniques like plant tissue culturing.
1. INTRODUCTION
Orchidaceae is a large, diverse family of angiosperms known for its distinctive flower morphologies. Worldwide, there are approximately 28,484 species and 850 genera of orchids [1]. Orchids grow in various habitats, including lithophytic, epiphytic, or terrestrial. Among them, 25% are terrestrial, and approximately 70% are epiphytic or lithophytic [2]. Orchids are cultivated for their ornamental value due to their exotic beauty and high durability [3,4]. Chinese was the first researchers to discover and develop orchids with therapeutic properties [5]. Orchids contain a wide range of bioactive substances that have been utilized to treat various diseases [6]. The bioactive components extracted from orchids include alkaloids, dactylorhins, sinensols, and spiranthols. These diverse metabolites found in different orchid species provide benefits in the treatment of conditions such as rheumatoid arthritis, bacterial infections, inflammation, neuroprotection, anti-carcinogenesis, diuretic effects, anti-aging properties, wound healing, hypoglycemia, and anti-tumor activities in humans as mentioned in Table 1 [7-10]. Orchids also hold cultural value in various nations and tribes worldwide, where they are used as food and herbal medicines [11].
Table 1: Medicinal uses of some orchids.
| Botanical name | Medicinal uses | References |
|---|---|---|
| Aerides multiflora Roxb | The leaf paste is used to treat rheumatism. | [8] |
| Calanthe tricarinata Lindl | The paste of the leaf is used to treat sores and eczema. | [6] |
| Coelogyne cristata Lindl | Treat wounds, burns, and skin disease. | [9] |
| Coelogyne prolifera Lindl | Headache and fever relief using the paste of pseudobulbs. | [9] |
| Dendrobium amoenum Wall. ex Lindl. | The whole plant powder is employed to treat burnt skin and broken bones. | [9] |
| Eulophia dabia (D.Don) Hochr | Rhizome paste is used to treat cough and cold. | [9] |
| Habenaria furcifera Lindl | The plant is used for wound healing. | [9] |
| Liparis odorata (Willd.) Lindl. | The leaf paste is used for diabetic ulcer. | [8] |
| Pholidota imbricata Hook | Pseudobulb with mustard oil is used to treat joint discomfort. | [8] |
| Rhynchostylis retusa (L.) Blume | The juice of leaf is used to treat constipation. | [8] |
| Spiranthes sinensis (Pers.) Ames | The root and stem paste is used for curing sores. | [9] |
| Vanda cristata Wall. ex Lindl. | Fresh juice is consumed as a tonic to promote body growth and treat cough and cold. | [10] |
Globally, orchids are flowering plant species at risk of extinction. It is important to promote conservation efforts for the diverse and significant plant family Orchidaceae [12]. In many regions, the number of orchids with medicinal and horticultural significance is declining due to habitat destruction, overexploitation, and climate change and is classified as rare, endangered, or threatened in the international union for conservation of nature (IUCN) Red List [13,14]. There is an urgent need to preserve these orchids and different conservation methods have been developed to safeguard their biodiversity. The different in vitro strategies such as micropropagation, synthetic seed formation, and cryopreservation are highly valuable techniques in preserving these plants from extinction [15]. According to the Orchid conservation alliance, preserving natural orchid habitats is essential for the survival of orchids [16]. This review aims to narrate the threats, in situ and ex situ conservation measures employed to protect the orchids.
2. CONSERVATION STATUS AND THREATS
According to the APG III classification system (2009), Orchidaceae is divided into five subfamilies, namely, Apostasioideae, Cypripedioideae, Vanilloideae, Epidendroideae, and Orchidoideae [17]. In present, there are 28,484 recognized and accepted species within the family [18]. These plants are highly sensitive to pollution in their habitats and require special attention to ensure their survival [19]. The entire group of orchids faces threats due to the severe reduction of forest areas. In addition, habitat degradation and various human activities have led to a decline in a number of certain orchid species in India [20]. According to reports, over 50% of orchid species face threats due to their extensive use in traditional medicine. Primarily due to habitat degradation and extensive collection, approximately 90% of Cypripedioideae species (slipper orchids) in the Global Red List are declared as threatened [21]. Appendix I of the Red List includes Renanthera imschootiana (commonly known as “Red Vanda” in Manipur), and approximately ten species of Paphiopedilum. The Liparis olivacea has become extinct and Dactylorhiza hatagirea (Himalayan medicinal orchid) is critically endangered listed in Appendix I of convention on international trade in endangered species (CITES) [22,23]. Many orchid species are classified as endangered, rare, and included in Appendix II of CITES due to natural and human-induced threats. The Appendix II lists 1295 species from 179 genera found in India, including Aerides, Acampe, Androcorys, Bulbophyllum, Ceratostylis, Cymbidium, Dactylorhiza, Epipactis, Gastrochilus, Goodyera, Habenaria, Herminium, Liparis, Malaxis, Nervilia, Ornithochilus, Peristylis, Pholidota, and Rhynchostylis retusa [24]. By the end of 2017, 948 orchid species had been mentioned in the IUCN Global Red List, with approximately 56.5% classified as threatened [25]. Therefore, to prevent these rare plants continued extinction, their protection and conservation must be given the highest priority.
3. CONSERVATION MEASURES
The legislative measures, in situ preservation in sanctuaries/reserves and ex situ preservation in orchidaria/botanical gardens are the three primary approaches for safeguarding the genetic resources of orchid species [26].
3.1. Governmental Action
The IUCN maintains a protection program for CITES of wild plants and animals. Orchids are recognized as threatened species under this agreement. The endangered and extinct species are listed in Appendix I, where the trade of wild plants is strictly prohibited. However, the trade of cultivated and artificially propagated plants is allowed with proper authorization. The species listed in Appendix II may be at risk if trade is not carefully regulated. Almost, all members of the Orchidaceae family are listed in Appendix II. In India, the Wildlife Protection Act (1972) enacted by the government includes R. imschootiana (Red Vanda) and Vanda coerulea (Blue Vanda) in Schedule VI. The laws have played a crucial role in illegally collecting orchids from the wild [27].
3.2. In situ Conservation
In situ conservation aims to protect all living things, particularly wild flora, fauna, and threatened species within their natural environment. Turkey is the first to have a national strategy for preserving genetic diversity in its natural habitat [28]. Examples of in situ preservation include biosphere reserves, sanctuaries, and national parks. A biosphere reserve is a large protected area for the preservation of plant and animal resources where certain activities such as plantation, agriculture, grazing, tree cutting, hunting, and poaching are strictly prohibited. The “Man and Biosphere” initiative, proposed by United Nations educational, scientific, and cultural organization (UNESCO), introduced the concept of biosphere reserves in 1971. The first biosphere reserve in the world was established in 1979 [27]. At present, there are 738 biosphere reserves in 134 countries, including 22 transboundary locations. In India, there are 18 biosphere reserves, namely, Agasthyamalai, Kachchh, Cold Desert, Great Nicobar, Manas, Sunderbans, Similipal, Dibru-Saikhowa, Panna, Seshachalam hills, Achanakmar Amarkantak, Nanda Devi, Nilgiri, Nokrek protecting rare, endangered, and vulnerable orchid species. Similipal is the ninth biosphere reserve in India, containing 96 orchid species listed by UNESCO. It serves as a reservoir for epiphytic and terrestrial orchids in Odisha. Eria meghasaniensis and Tainia hookeriana are endemic orchids found exclusively in Similipal Biosphere Reserve [29].
A national park is a highly significant area with stunning landscapes protected and maintained by the government to conserve flora and fauna. The human activities such as mining, hunting, and fishing are prohibited in national parks to preserve their natural areas. The Jim Corbett National Park, established in 1936, was the first national park in India. At present, there are 106 active national parks in India, including Rani Jhansi Marine, Mount Harriett, Papikonda, South Button Island, Indravati, Khirganga, and Great Himalayan, which collectively cover an area of 44,402.95 km2 (National Wildlife Database 2023). Ninety-Six different orchid species inhabit the Similipal National Park in Odisha, while the Buxa Tiger Reserve in West Bengal has 150 different orchid species [27]. The Kaziranga Orchid National Park is the largest orchid national park having approximately 600 types of wild orchids collected from North-east India.
Sacred groves are small areas holding religious importance to preserve various plants and animal species useful for food, medicine, and other purposes [30]. The various states of India, including Himachal Pradesh, Karnataka, Maharashtra, West Bengal, and Chhattisgarh are well-known for their sacred groves. There are 13,270 known sacred groves in India, and 5627 are located in the Indian Himalayan area. In Arunachal Pradesh, Sessa Orchid Sanctuary is the first and only protected area in the country for the preservation of naturally growing orchids. Hadimba Devi (Kullu District of Himachal Pradesh) recorded Calanthe tricarinata, Epipactis helleborine, and Herminium lanceum, while Rupasana Devi reported E. helleborine, Habenaria edgeworthii, and H. lanceum. The sacred groves of Jamdagni Rishi are inhabited by H. edgeworthii, Goodyera repens, E. helleborine, and Spiranthes sinensis while C. tricarinata, and H. edgeworthii are found in the sacred groves of Shangchul Rishi [31].
3.3. Ex situ Conservation
Ex situ conservation is a method of protecting species (plants or animals) outside their original environment. It involves relocating genetic material from its native location, allowing for easy access to germplasm for research and utilization. It is considered the most practical, cost-effective, and widely practiced form of conservation. In India, the Botanical Survey of India maintains three National Orchidaria and Experimental Gardens, located in Yercaud, Howrah, and Shillong. The State Forest Research Institute of Arunachal Pradesh carries out ex situ conservation by preserving a variety of orchid species in the Orchid Research Centre situated in Tipi, Itanagar, Dirrang, Jenging, and Sessa [27].
The most popular ex situ conservation techniques include a botanical garden, in vitro propagation, cryopreservation, gene banks, and seed storage. A botanical garden, also referred to as a botanic garden, is a collection of living plants and plays a key role in conservation. Organizations like the New York Botanical Garden and Royal Botanic Garden (Kew) maintain living orchid collections, and conduct ongoing research initiatives [31]. In India, there are currently 13 botanical gardens that preserve various orchid species. The Lloyd Botanical Garden in Darjeeling, West Bengal, has 43 collected orchid species [27]. The Botanical Garden and National Orchidarium, located near Umiam Lake in Barapani, is approximately 22 km from Shillong has 419 orchid species from 94 genera collected from various states in North-east India. Each species is documented with its botanical name, place of collection, flowering-fruiting season, habitat, and IUCN status. The major orchid genera preserved in the garden include Bulbophyllum, Dendrobium, Coelogyne, Cymbidium, Liparis, Oberonia, and Paphiopedilum. In addition, the orchidarium recorded other fascinating genera such as Anoectochilus brevilabris, Acanthephippium sylhetense, Armodorum senapatianum, Bulbophyllum rothschildianum, Cymbidium dayanaum, Neogyna gardneriana, Paphiopedilum venustum, and R. imschootiana.
A seed bank is designed to preserve and protect the genetic diversity of seeds. The largest seed bank is the Millennium Seed Bank, located in Sussex, which is operated and supervised by the Royal Botanic Gardens, Kew. Orchids produce numerous seeds within a single capsule. However, these seeds lack a viable endosperm under natural conditions and require a specific mycorrhizal association for germination. As a result, the germination rate of orchid seeds is typically low. The orchid seeds (Dactylorhiza, Dendrobium, Eulophia, and Paphiopedilum) are preserved at −70°C to maintain their high viability. These seeds have shown excellent potential for long-term storage at low temperatures [27].
Cryopreservation is a technique used to preserve plant organs and reproductive components by storing them in liquid nitrogen at a temperature of −196°C. Cryopreservatives are particularly useful for preserving seeds with high moisture content. The orchid tissues and explants can be successfully cryopreserved in liquid nitrogen cylinders by treating them with cryoprotectants and plant vitrification solutions. In India, Cryobank facilities have been established by the national bureau of plant genetic resources, which preserves 2.5 lakh germplasm lines [27]. This technique has become an affordable method for preserving endangered species.
The in vitro technique is a biotechnology method used for secondary metabolite production, virus eradication, and mass propagation [32]. The various types of explants, including seeds, shoots, roots, leaf apexes, nodal segments, rhizomes, and pseudobulbs have been commonly used to micropropagate different orchid species [33]. This technique enables the production of healthy and disease-free plants on a large scale. It is highly effective for conserving the gene pool and biodiversity. The in vitro culture is the only viable method to preserve and reintroduce threatened genetic material into the environment. It is considered the best technique for conserving rare or endangered orchids with ornamental and medicinal significance [34].
4. CONCLUSION AND FUTURE PERSPECTIVES
The conservation of orchids is a critical task that demands immediate attention and action. By implementing effective conservation strategies, we can secure the survival of orchid species and preserve the benefits they provide to the environment and society. It is vital to prevent the extinction of orchids and safeguard their ecological and cultural significance. These strategies should encompass habitat preservation, particularly in areas abundant with orchids, and regulation of harvesting practices. The local people should be made aware to protect the wild orchids in their area. Hence, public awareness can play a significant role in promoting orchid conservation. Overall, orchid conservation necessitates collaborative efforts from governments, organizations, scientists, and the general public to preserve these exquisite and ecologically significant medicinal plants for future generations.
5. AUTHORS’ CONTRIBUTIONS
All authors made substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; took part in drafting the article or revising it critically for important intellectual content; agreed to submit to the current journal; gave final approval of the version to be published; and agreed to be accountable for all aspects of the work.
6. FUNDING
There is no funding to report.
7. CONFLICTS OF INTEREST
The authors report no financial or any other conflicts of interest in this work.
8. ETHICAL APPROVALS
This study does not involve experiments on animals or human subjects.
9. DATA AVAILABILITY
All data generated and analyzed are included within this review article.
10. PUBLISHER’S NOTE
This journal remains neutral with regard to jurisdictional claims in published institutional affiliation.
REFERENCES
1. Sharma A, Pathak P. The budding potential of orchids in the cosmeceutical sector: Role of orchids in skincare and health. J Orchid Soc India 2020;34:79-85.
2. Swarts ND, Dixon KW. Perspectives on orchid conservation in botanic gardens. Trends Plant Sci 2009;14:590-8. [https://doi.org/10.1016/j.tplants.2009.07.008]
3. Sarmah D, Kolukunde S, Sutradhar M, Singh BK, Mandal T, Mandal N. A review on:In vitro cloning of orchids. Int J Curr Microbiol Appl Sci 2017;6:1909-27. [https://doi.org/10.20546/ijcmas.2017.609.235]
4. Maitra S, Sairam S, Shankar T, Gaikwad DJ. Growing of Dendrobium orchids in greenhouse. In:Protected Cultivation and Smart Agriculture. New Delhi, India: New Delhi Publishers;2020. 270-7. [https://doi.org/10.30954/NDP-PCSA.2020.30]
5. Bulpitt CJ. The uses and misuses of orchids in medicine. QJM 2005;98:625-31. [https://doi.org/10.1093/qjmed/hci094]
6. Pant B. Medicinal orchids and their uses: Tissue culture a potential alternative for conservation. Afr J Plant Sci 2013;7:448-67. [https://doi.org/10.5897/AJPS2013.1031]
7. Pathak P, Bhattacharya A, Vij SP, Mahant KC, Dhillon MK, Piri H. An update on the medicinal orchids of Himachal Pradesh with brief notes on their habit, distribution and flowering period. J Non Timber For Prod 2010;17:365-72.
8. Panda AK, Mandal D. The folklore medicinal orchids of Sikkim. Anc Sci Life 2013;33:92-6. [https://doi.org/10.4103/0257-7941.139043]
9. Chakraborty A, Pal N, Thanvi HA, Dhal A, Debi C, Kumar S, et al. Medicinally important common orchids of India. In:Medico-biowealth of India. Vol. 5. Cuttack, Odisha:Ambika Prasad Research Foundation;2022. 25-9.
10. Singh B. Therapeutic Himalayan herbs:Folklore uses, bioactive phytochemicals, and biological activities of medicinal orchids used by Nomads. Indian J Nat Prod Resour 2022;13:94-104.
11. Kasulo V, Mwabumba L, Cry M. A review of edible orchids in Malawi. J Hortic For 2009;1:133-9.
12. Swarts ND, Dixon KW. Terrestrial orchid conservation in the age of extinction. Ann Bot 2009;104:543-56. [https://doi.org/10.1093/aob/mcp025]
13. Prakash A, Pathak P. Orchids of Water Catchment Wildlife Sanctuary, Shimla (Himachal Pradesh), Northwestern Himalayas: Their diversity, status, indigenous uses, and conservation status. J Orchid Soc India 2019;33:65-77.
14. Chase MW, Cameron KM, Freudenstein JV, Pridgeon AM, Salazar G, van den Berg C, et al. An updated classification of Orchidaceae. Bot J Linn Soc 2015;177:151-74. [https://doi.org/10.1111/boj.12234]
15. Anuprabha PP, Prakash A, Kumar J. Regeneration competence of Dendrobium nobile Lindl. through pseudobulb segments:A study in vitro. J Orchid Soc India 2017;31:71-5.
16. Marks TR, Seaton P, Pritchard HW, Kendon JP, Puspitaningtyas DM. Orchid conservation:The next ten years. Lankesteriana 2013;13:93-101.
17. Li MH, Zhang GQ, Lan SR, Liu ZJ, China Phylogeny Consortium. A molecular phylogeny of Chinese orchids. J Syst Evol 2016;54:349-62. [https://doi.org/10.1111/jse.12187]
18. Faruk A, Papikyan A, Nersesyan A. Exploring effective conservation of charismatic flora:Orchids in Armenia as a case study. Diversity 2021;13:624. [https://doi.org/10.3390/d13120624]
19. Barua KN, Bora B, Borah A. Diversity and ex situ conservation of orchid species in Lekhapani reserve forest under Makum coal field, Assam. J Orchid Soc India 2019;33:113-9.
20. Bhandari PK, Thakur J, Sharma S, Uniyal PL. Orchid diversity in Basukedar region (Rudraprayag district) of Uttarakhand. J Orchid Soc India 2018;32:73-9.
21. Fay MF. Orchid conservation: How can we meet the challenges in the twenty-first century?Bot Stud 2018;59:16. [https://doi.org/10.1186/s40529-018-0232-z]
22. Subedi A, Kunwar B, Choi Y, Dai Y, Van Andel T, Chaudhary RP, et al. Collection and trade of wild-harvested orchids in Nepal. J Ethnobiol Ethnomed 2013;9:64. [https://doi.org/10.1186/1746-4269-9-64]
23. Giri D, Arya D, Tamta S, Tewari LM. Dwindling of an endangered orchid Dactylorhiza hatagirea (D. Don) Soo:A case study from Tungnath Alpine meadows of Garhwal Himalaya, India. Nat Sci 2008;6:6-9.
24. Hagsater E, Dumont V, Pridgeon AM, editors. Orchids:Status Survey and Conservation Action Plan. Vol. 28. Cambridge, UK:IUCN;1996.
25. Herrera H, Garcia-Romera I, Meneses C, Pereira G, Arriagada C. Orchid mycorrhizal interactions on the Pacific side of the Andes from Chile. A review. J Soil Sci Plant Nutr 2019;19:187-202. [https://doi.org/10.1007/s42729-019-00026-x]
26. De LC, Rao AN, Singh DR. Endangered orchids and their conservation in North East India. In:Bioprospecting of Indigenous Bioresources of North-East India. Germany:Springer;2016. 61-75. [https://doi.org/10.1007/978-981-10-0620-3_5]
27. De LC, Pathak P. Conservation, management, and utilization of orchid genetic resources. J Orchid Soc India 2018;32:81-91.
28. Kaya Z, Raynal DJ. Biodiversity and conservation of Turkish forests. Biol Conserv 2001;97:131-41. [https://doi.org/10.1016/S0006-3207(00)00069-0]
29. Kumar S, Mishra S, Mishra AK. Diversity of orchid species of Odisha state, India. With note on the medicinal and economic uses. Richardiana 2021;5:1-26.
30. Kumar D, Kumari P, Samant SS, Paul S. Assessment of orchid diversity in selected sacred groves of Kullu district, Himachal Pradesh, India. J Orchid Soc India 2016;30:89-95.
31. Swarts ND, Dixon KW. Conservation Methods for Terrestrial Orchids. Fort Lauderdale:J Ross Publishing;2017. 240.
32. Oseni OM, Pande V, Nailwal TK. A review on plant tissue culture, a technique for propagation and conservation of endangered plant species. Int J Curr Microbiol Appl Sci 2018;7:3778-86. [https://doi.org/10.20546/ijcmas.2018.707.438]
33. Lal N, Singh M. Prospects of plant tissue culture in orchid propagation:A review. Indian J Biol 2020;7:103-10.
34. Bhowmik TK, Rahman MM. Effect of different basal media and PGRs on in vitro seed germination and seedling development of medicinally important orchid Cymbidium aloifolium (L.) Sw. J Pharmacogn Phytochem 2017;6:167-72.
APPENDIX
Appendix I
| Botanical name | IUCN Status |
|---|---|
| Renanthera imschootiana (Rolfe) | Endangered |
| Paphiopedilum charlesworthii (Rolfe) | Endangered |
| Paphiopedilum druryi (Bedd.) Stein | Critically Endangered |
| Paphiopedilum fairrieanum (Lindl.) Stein | Critically Endangered |
| Paphiopedilum hirsutissimum (Lindl. ex Hook.) Stein | Vulnerable |
| Paphiopedilum insigne (Wall. ex Lindl.) Pfitzer | Endangered |
| Paphiopedilum spicerianum (Rchb. f.) Pfitzer | Endangered |
| Paphiopedilum venustum (Wall. ex Sims) Pfitzer | Endangered |
| Paphiopedilum villosum (Lindl.) Stein | Vulnerable |
| Paphiopedilum wardii Summerh | Endangered |
| Liparis olivacea Lindl. | Extinct |
| Dactylorhiza hatagirea (D. Don) Soo | Critically Endangered |
Appendix II
| Botanical name | IUCN Status |
|---|---|
| Aerides odorata Lour | Endangered |
| Acampe praemorsa (Roxb.) Blatt. & Mc Cann | Least Concern |
| Androcorys angustilabris (King & Pantl.) | Near threatened |
| Bulbophyllum helenae (Kuntze) J.J. Sm | Endangered |
| Ceratostylis subulata Blume | Near threatened |
| Cymbidium iridioides (D. Don) | Near threatened |
| Dactylorhiza hatagirea (D. Don) Soo | Critically endangered |
| Epipactis helleborine (L.) Crantz | Threatened |
| Gastrochilus calceolaris (Buch.-Ham. ex Sm.) D. Don | Critically endangered |
| Goodyera repens (L.) R.Br. | Near threatened |
| Habenaria intermedia D. Don | Endangered |
| Malaxis acuminata D. Don | Endangered |
| Liparis odorata (Willd.) Lindl. | Near threatened |
| Nervilia crociformis (Zoll. ex Moritzi) Seidenf | Near threatened |
| Ornithochilus difformis (Wall. ex Lindl.) Schltr | Near threatened |
| Pholidota pallida Lindl. | Near threatened |
| Peristylis lacertiferus (Lindl.) | Endangered |
| Peristylis lacertiferus (Lindl.) J.J. Sm. | Endangered |
| Rhynchostylis retusa (L.) | Endangered |