Overview

India has one of the richest plant medical cultures in the world. In the oral traditions local communities in every ecosystem from the trans Himalayas down to the coastal plains have discovered the medical use of thousands of plants found locally in their ecosystem. The tremendous passion for the medicinal plants made the people to use them for a wide range of health related applications from a common cold to memory improvement and treatment of poisonous snake bites to a cure for muscular dystrophy and the enhancement of body's general immunity.

Ancient Indian literatures incorporate a remarkably broad definition of medicinal plants and considers 'all' plants as potential sources of medicinal substances ("Jagatyevananaoushadham na kincit vidyate dravyam vasannaanartha yogayoh" - Source: Ashtanga hirdaya. SU.9-10). But, at a practical level, only those plants whose medicinal use has already been discovered for human or veterinary application are considered "medicinal". There are estimated to be around 8000 species of medicinal plants that are used in different systems of Indian medicine.

Medicinal plant has traditionally occupied an important position in the socio cultural, spiritual and medicinal arena of rural and tribal lives of India. The remarkable fact is that it is still a living tradition. This is borne out by the fact that there still exist around a million traditional, village-based carriers of herbal medicine systems in the form of traditional birth attendants, bonesetters, herbal healers and wandering monks. Apart from these specialised carriers there are millions of women and elders who have traditional knowledge of herbal-remedies and of food and nutrition.

Complementing the village based carriers, there are around 6 lakh licensed, registered medical practitioners of the codified systems of Indian Medicine like Ayurvedic, Siddha, Unani and the Tibetan system of medicine.  These codified systems have sophisticated theoretical foundation and there are hundreds of medical tests in the form of Nighantus (Lexicons) and texts on Bhaisajya Kalpana (pharmacy) that specifically deal with plants and plant's products.

There are estimated to be around 25000 effective plant based formulations used in folk medicine and known to rural communities all over India and around 10000 designed formulations are available in the indigenous medical texts.

Traditionally medicinal plants have been used for human, veterinary and plant health.  There are medical texts that deal with the treatment of cows, horses, elephants and birds.  There are also texts on subjects like Vrksh-ayurveda that deal with use of plants for controlling pests, treating plant diseases and as bio-fertilizers.

It may be worth observing that the knowledge of the Indians about plants and plant-products is not based on the application of western system of knowledge or scientific approaches to natural products like chemistry or pharmacology.  It is based on a sophisticated, indigenous knowledge category called "Dravya Gun Shastra".  Unfortunately due to lack of rigorous cross cultural studies and in the absence of a well accepted methodology for such cross cultural studies, there exists no  "reliable bridge" to cross over from chemistry and pharmacology to "Dravya Gun Shastra" or vice-versa, although functional links have been established. 

 

AYURVEDA

FOLK

HOMEO

MODERN

SIDHA

TIBETAN

UNANI

AYURVEDA

2351

900

189

80

1028

341

880

FOLK

900

5137

164

86

971

235

573

HOMEO

189

164

506

100

167

77

173

MODERN

80

86

100

204

65

25

75

SIDHA

1028

971

167

65

1785

277

641

TIBETAN

341

235

77

25

277

350

275

UNANI

880

573

173

75

641

275

979

Count of medicinal plants usage across different systems of Indian Medicine

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Medicinal Plant resources of India

Medicinal plants as a group comprise approximately 8000 species and account for around 50% of all the higher flowering plant species of India. The largest number of medicinal plants are known to occur in dry deciduous forest as compared to the evergreen or temperate forests.

Macro analysis of the distribution of medicinal plants show that they are distributed across diverse habitats and landscapes across the country.  Around 70% of them are found in tropical areas mostly in the various forest types spread across the Western and Eastern Ghats, the Vindhyas, Chotta Nagpur plateau, Aravalis & Himalayas.  Although less than 30% of the medicinal plants are found in the temperate and alpine areas and higher altitudes they include species of high medicinal value. A smaller number is also seen in aquatic habitats and mangroves.     

In order to have a broad picture of the medicinal plant diversity of the country, an attempt has been made to enlist them under different bio-geographic zone or region. The 'Trans Himalayan' bio-geographic zone is estimated to harbour approximately 700 known medicinal plant species.  Some of the well known ones, existing in the very cold and desert like conditions of this region are Ephedra gerardiana Wall., Hippophae rhamnoides L., Arnebia euchroma (Royle) John etc. The 'Himalayan' zone consists of North-West Himalayas, West Himalayas, Central Himalayas and East Himalayas biotic provinces. The North-West and West Himalayas region is estimated to have approximately 1,700 known medicinal plant species.  Some of the well-known species of these regions are Aconitum heterophyllum Wall. Ex Royle, Ferula jaeschkeana Vatkeand Saussurea costus (Balc.) Lipsd.  S. costus (syn. S. lappa C. B. Clarke) is in fact confined to only the Himalayan region of Jammu & Kashmir state and is cultivated elsewhere, including Lahaul district of Himachal Pradesh. This critically endangered variety, in the wild, is enlisted in Appendix I of CITES (Convention on International Trade in Endangered Species of flora and fauna).  The Central and Eastern Himalayan biotic provinces, put together, are estimated to harbour around 1,200 known medicinal plant species.  A few of the well known ones are Nardostachys grandiflora DC., Taxus wallichiana Zucc., Rhododendron anthopogon D.Don and Panax pseudoginseng Wall.  While Panax pseudoginseng is seen only in the Eastern Himalayas, Nardostachys grandiflora DC and Taxus wallichiana Zucc have already been included in Appendix II of CITES.

Despite the fact that the 'Desert' bio-geographic zone consisting of Kutch and Thar biotic provinces support only sparse vegetation, it is a haven for almost 500 known medicinal plant species.  Some of the well-known ones of this region are Convolvulus microphyllus Seib ex Spreng (Syn C. pluricaulis Chois), Tecomella undulata (Sm.)Seem, Citrullus colocynthis (L.) Schraderand Cressa cretica L.

The 'Semi-Arid' zone consists of biotic provinces of Punjab and Gujarat - Rajwar and is estimated to be a home for around 1,000 known medicinal plant species. Commiphora wightii (A.) Bhandari, Caesalpinia bonduc (L.) Roxb., Balanites aegyptiaca (L.) Delile and Tribulus rajasthanensis Bhandari & Sharma are some of them. Tribulus rajasthanensis is almost endemic to this region in India while extending into adjoining areas of Pakistan.

Known for its rich bio-diversity, the "Western Ghats" bio-geographic zone consisting of Malabar coast and Western Ghats is one of the eighteen hot spots of bio-diversity recognized across the globe. Approximately 2000 known medicinal plant species, many of these are endemic to this region, are seen here.  Among its endemic species are Myristica malabarica Lam., Garcinia indica (Dup.) Choisy, Utleria salicifolia Bedd.and Vateria indica L. These species have been assessed to be under varying degree of threat of extinction ranging from Vulnerable (VU) in case of Vateria indica L. to Critically Endangered (CR) Utleria salicifolia Bedd.

The 'Deccan Peninsula' covers the largest chunk of land mass amongst all the ten bio-geographic zones consists of five biotic provinces - Deccan Plateau South, Central Plateau, Eastern Plateau, Chhota Nagpur and Central Highlands.  This zone has the highest proportion of India's entire medicinal plant diversity and the total number of known species is estimated to be around 3000.  The well known endemic species of this region are Pterocarpus santalinus L.f., Decalepis hamiltonii Wight & Arn., Terminalia pallida Brandisand Shorea tumbuggaia Roxb of which Pterocarpus santalinus L.f is already included in Appendix II of CITES.

The 'Gangetic Plain' consisting of Upper Gangetic Plain and Lower Gangetic Plain biotic provinces is estimated to have around 1000 known medicinal plant species. A few of the well known ones of this region are Holarrhena pubescens (Buch-Ham.) Wallich ex DC., Mallotus philippensis (Lam.) Muell.-Arg., Pluchea lanceolata C. B.Clarkeand Peganum harmala L.

The 'North-East India' with an estimated 2000 medicinal plant species population is yet another high bio-diversity region of the country. Like the Western Ghats, this zone is also one of the eighteen hot spots with high levels of endemism.  It consists of two biotic provinces namely Brahmaputra Valley and Assam Hills. Aquilaria malaccensis Lam., Smilax glabra Roxb., Ambroma augusta  (L.) L.f. and Hydnocarpus kurzii (King) Warb are some of the well-known medicinal plants found here. Out of these, A. malaccensis Lam., is already included in Appendix II of CITES.

Andaman, Nicobar and Lakshadweep Islands form the 'Island' bio-geographic zone. Calophyllum inophyllum L., Adenanthera pavonina L., Barringtonia asiatica (L.) Kurzand Aisandra butyracea (Roxb.) Baehni are some of the important medicinal plants of this zone which is estimated to have around 1000 species.

The 'Coasts' bio-geographic zone comprising West Coast and East Coast is estimated to harbour around 500 plant species of known medicinal value.  A few of the well known ones amongst these are Rhizophora mucronata Lam., Acanthus ilicifolius L., Avicennia marina Vierh and Sonneratia caseolaris  (L.) Engl.

Studies show that a large percentage of the known medicinal plants occur in the dry and moist deciduous vegetation as compared to the evergreen or temperate habitats.  This is perhaps due to more intensive human (anthropological) interaction with plants in the deciduous tracts as compared to evergreen forests and also there is a greater degree of speciation in tropical forests as compared to the temperate vegetation.

Life forms:

Majority of the medicinal plant are higher flowering plants. Of the known plants of medicinal value little more than one third are trees and an equal portion shrubs and climbers. While herbs constitutes around one third of the total population, medicinal species are also found in lower plants like algae, fungi, lichens, bryophytes, pteridophytes, gymnosperms and angiosperms.

Families:

Of the 386 families and 2200 genera recorded, the families Asteraceae, Euphorbiaceae, Lamiaceae, Fabaceae, Rubiaceae, Poaceae, Acanthaceae, Rosaceae and Apiaceae share the larger proportion of medicinal plant species, with the highest number of species (419) falling under Asteraceae.

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Need for conservation:

Medicinal plants are living resource, exhaustible if overused and sustainable if used with care and wisdom. Their sustainability is essential to sustain one of world's oldest medical traditions, a priceless legacy of the Indians. Millions of rural households still use medicinal plants in a self-help mode. Over one and a half million practitioners of the Indian systems of medicine, in the oral and codified streams, use medicinal plants in preventive, promotive and curative applications.

There are estimated to be over 8000 herbal product-manufacturing units in India with a combined annual turnover of over Rs.4000 crores/year.  In recent years, the growing demand for herbal products has led to a quantum jump in volumes of plant material traded within and across countries.  Conservative estimates put the economic value of medicinal plant related International trade to be of the order of US $ 880 million and this is growing. 

While the demand for medicinal plants is increasing, their survival in their natural habitats is under growing threat. Several medicinal plants have been assessed as endangered, vulnerable and threatened due to over harvesting in the wild. Rapid loss and fragmentation of natural habitats is an added danger. Species like Coscinium fenestratum, Janakia arayalpathra, Dactylorhiza hatagirea, Saussurea costus are critically endangered in the wild. It is expected that around a 1000 species of medicinal plants are facing threat to their existence in the wild and some of them like Plectranthus vettiveroides have become extinct. For meeting the future needs cultivation of medicinal plant has to be encouraged.

Medicinal plants are potential renewable natural resources.  Therefore, the conservation and sustainable utilisation of medicinal plants must necessarily involve a long-term programme. A holistic and systematic approach envisaging interaction between social, economic and ecological systems will be a more desirable one.  The most widely accepted scientific technologies of biodiversity conservation are the in-situ conservation and cultivation methods.

The best and cost-effective way of protecting biological and genetic diversity is the 'in-situ' or on the site conservation wherein a wild species or stock of a biological community is protected and preserved in its natural habitat.  The prospect of such an 'ecocentric', rather than a species centred approach is that it will prevent species from becoming endangered by human activities and reduce the need for human intervention to prevent premature extinctions.  Establishment of biosphere reserves, national parks, wild life sanctuaries, sacred groves and other protected areas forms examples of 'in-situ' methods of conservation.  In situ conservation thus serves the purpose of long term survival and evolution of a species, in association with other plant, animal & microbial associates in the Eco-system.

The term 'cultivation' generally implies selection of a particular variety of a species and large-scale multiplication of that particular variety to meet the requirements of consumption.  The intention behind cultivation is consumption. Though some highly productive or high quality individuals may be chosen for providing large-scale propagation material, the progeny used in cultivation is expected to have narrow genetic variation.  It is likely to be more susceptible to pests and diseases than natural populations. 

Thus, in situ conservation and cultivation serve entirely different purposes although both are important and relevant in their respective contexts. While cultivation can reduce pressure on the wild populations, it cannot replace them. The wild populations need to be preferably conserved as gene pools, rather than be used as raw material for consumption.

Role of In situ conservation:

It is only in their natural habitats (in situ) that breeding populations of plants can survive so as to evolve.  Even if we put a particular variety of a particular species under millions of hectares of cultivation, the species can still go extinct in the wild, leading to loss of certain strains or genes absent in the cultivated stock. Therefore, no cultivation strategy can ever ensure the survival of species.  In fact, in order to sustain a viable cultivation programme, it is essential to maintain the intra-specific diversity or the germplasm of species because it is the germplasm, which provides opportunities for selecting a desired variety or for breeding a new one.  The ideal way to maintain the intra-specific variation within the species is the way nature does it i.e. through an in situ conservation strategy.  This is the healthiest and most cost-effective way to maintain germplasm of a species, as other ex situ conservation measures such as cryopreservation i.e., deep refrigeration requires prohibitively high costs and human skills. In situ conservation is also the only way to ensure long-term survival of the medicinal plants diversity of a region.

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The conservation status of Indian Medicinal Plants

An estimated 881 species are currently used in Industry for production of herbal products. Around 60 species are imported, about 60 species are cultivated and about 760 species are harvested from the wild. Thus around 90 percent of medicinal plants used by the Indian Industry are collected from the wild. Out of this, more than 70 percent of the collections involve destructive harvesting from the wild, because of the use of parts like roots, bark, wood, stem and also the whole plant in some cases. This poses a definite threat to the genetic stocks and to the diversity of medicinal plants.

How to prioritise medicinal plants of conservation concern?

The prioritisation of native medicinal plants of conservation concern could be done on the basis of the following;

  1. Their endemism i.e., being confined to narrow regions.
    Eg: Cycas beddomei Dyer of Central A.P
  2. Enlistment in published Red Data Books,
    Eg: Hidegardia populifolia
  3. High volume consumption by the traditional medicine industries,
    Eg: Ravolfia serpertina, Garcinia indica, Coscinium fenestratum
  4. Traded species that involve destructive harvesting.
    Eg: Pterocarpus santalinus, Decalepis hamiltonii, Oroxylum indicum
  5. Phylogenetic distinctness i.e., fewer number of species per genus or family
    Eg: Decalepis hamiltonii -monotypic i.e., the genus Decalepis has only one species. The species thus prioritised need to be assessed in order to find out if their populations which are actually under threat and to what extent.

How to assess the 'threat' status of a species?

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IUCN Threat Categories:

IUCN threat categories primarily assess the probability of the species becoming globally extinct owing to its small population size or high population decline rate. The threat categories have been frequently revised by the Species Survival Commission (SSC) group of the IUCN for application to several macroscopic organisms. Latest IUCN red listing i.e. 2000 system recognizes three threatened categories reflecting different population growth rates.
1. Critically Endangered (CR)
2. Endangered (EN)
3. Vulnerable (VU)

Other categories of conservation concern, but not threatened are:

  1. Near Threatened (NT) [Akin to Conservation Dependent in earlier version, where deliberate conservation measures are needed to prevent the taxon from meeting the threatened criteria.]
  2. Least Concern (LC) [i.e. Low Risk as in earlier version, which doesn't mean that the species can stand neglect or over-exploitation, it's just that it is not immediately prone to extinction.]
Other categories defined by IUCN are
  1. Extinct in the wild (EX-W) when only captive breeding under ex situ conditions is possible.
  2. Extinct globally (EX).
  3. Data deficient (DD), which does not mean that the species is not threatened, but that the threat can be judged only after collection of adequate data.
  4. Not evaluated (NE) includes several species that were not evaluated primarily because those were too abundant to be of foreseeable conservation concern.

IUCN Threat Criteria
Each of these threat categories can be deduced based on any one of the five criteria that reflect extinction risk:

  1. Declining population (past or projected): This includes species with high harvests, especially in destructive fashion. Eg: Rauvolfia serpentina
  2. Narrow distribution, fragmentation and decline or fluctuation: Several endemic species prima facie appear to be natural candidates for qualifying as threatened as per this criterion. Eg: Cyas beddomei
  3. Small population size and decline: Absolute population number low and rate of decline high.
  4. Very small population or very restricted distribution: Absolute population numbers/ expanse extremely meagre.
  5. Quantitative analysis of probability of extinction: simulations using deterministic and stochastic population models.

The five quantitative criteria aim at detecting risk factors across a broad range of organisms and the diverse life histories they exhibit. The quantitative values in each criterion were developed through consultation, but there also exists modest formal justification for these values. Meeting any one of these five criteria qualifies a taxon (species or lower e.g. variety) for listing at that level of threat. If a taxon meets two or more threat criteria/categories, the higher risk status and corresponding risk criteria is accepted. For, being inactive given the lower threat status on one criterion exposes the species to extinction due to the other criterion. Although the criteria for each of the threat categories are based on quantitative thresholds such as enumeration or observation, inference such as from records of habitat area decline or projection such as growing market demand etc. are permitted. Thus, the taxa for which there exists very little population information can also be assessed, using IUCN criteria and their participatory application in Conservation Assessment and Management (CAMP) workshops.

Why rapid methods for threat assessment are needed?

To promote red listing in the tropics by overcoming the lacunae of data, Conservation of Breeding Specialist Group (CBSG) of the IUCN has developed a participatory rapid threat assessment method that synthesizes the first hand and even unpublished perceptions of direct or indirect resource users such as botanists, traders, forest officials. This method relies on a workshop to bring together the resource users. These Conservation Assessment and Management Plan (CAMP) workshops detect threat levels, their causes and corrective management options for highly traded and endemic species.


How much work has been done so far on threat status of Indian Medicinal Plants?

Globally, about 10 percent of the known flowering plants are threatened with extinction. Similar estimates have been made for India also. In comparison with the magnitude of possibly threatened species of medicinal plants only preliminary work on identifying threatened species has been initiated. Since the rapid methods are not perfect, they do provide the first indications of threat. To focus on threat assessment for medical plants the Foundation for Revitalisation of Local Health Traditions (FRLHT), Bangalore and CBSG-India are working jointly. FRLHT has facilitated six rapid assessment workshops in peninsular India during 1995-2001. The results include separate assessments for five states- Maharashtra, Andhra pradesh, Karnataka, Kerala, and Tamil Nadu, besides a consolidated, regional assessment for the latter three states i.e. southern India together. These six workshops covering five states were held at Bangalore (4), Pune (1) and Hyderabad (1) in the winter season (January to March) each year during 1995-2001. Over 200 experts including from BSI, forest official, industry employees, healers shared their views in these workshops.

In each of these workshops about 50 species were assessed, totalling to 161 unique species, as many (assessed) species were common across workshops, for reassessment or sub-regional assessment. Species endemic to Peninsular India (72) accounted for 40 percent of species assessed while majority of the species had less than 5 percent of their global population occurring in the region. Herbs (25 percent) and climbers (28 percent) each accounted for a quarter of the species assessed, while trees (44 percent) accounted for nearly a half, as these are in lower population sizes, regenerate far less and more susceptible to destructive practices such as de-barking or lopping.

Besides these peninsular Indian workshops, FRLHT facilitated a workshop for high elevation Himalayan plants from Jammu & Kashmir and Himachal Pradesh states, where 34 of the 42 species assessed were found threatened. Zoo Outreach Organization, Coimbatore also facilitated CAMP workshops at Lucknow that assessed 75 species of northern India of which 69 were found threatened.

Why species become threatened?

Over harvesting from wild is the reason for becoming threatened in the case of specific species that are traded in high volumes. Habitat loss and fragmentation affect over three fourths of the threatened species. Habitat degradation can be compensated through eco-restoration only if habitats have not been irreversibly lost. However, harvests, especially destructive practices can be minimized by regulations, providing much-needed breathing space for the threatened species populations to gradually restore. This is necessary as 90 percent of the raw material worth Rs.120 million used by the Indian herbal industry is today entirely harvested from the wild. Commercial cultivation to ease pressure on wild stock is presently not lucrative, as harvests from the wild are both available and much cheaper.

Limitations of IUCN categories and rapid assessment methods

The IUCN red listing has been used extensively both globally and in many countries for many taxa. However, IUCN categories reflect only relative extinction risks, ignoring many values often used for conservation prioritisation e.g. utility values, ecosystem functions, taxonomic distinctiveness, endemism and feasibility, though some of these are indirectly reflected in choice of species to be assessed by IUCN methodology. Ideally, a threat assessment methodology should also value intrinsic (pollination, dispersal modes and other reproductive bottlenecks, germination and survival rates etc.) factors that differentially affect different species exposed to same level of extrinsic threat (habitat loss, destructive harvest etc.). However, data relating to intrinsic threats are almost non-existent or very sketchy for most tropical species, including Indian. An inevitable limitation of IUCN methodology is that different species assigned to a single threat category may be susceptible to different intrinsic threats. For instance, amidst all species belonging to `vulnerable' category dioecious species such as many Ficus species are more threatened than monoecious species that dominate most genera. For, the former require higher population where fewer trees produce female flowers and fruits and self-pollination is impossible, being dependent on wasps.

A theoretical limitation of CAMP approach has been the emphasis on subjectivity of data coupled with attempt for consensus, which departs from the usual scientific practices that benefit from objectivity and divergence. While departure from mainstream is scientifically progressive, successful management needs social consensus rather than conflict, as attempted in the CAMP process. The CAMP version earlier excessively emphasized on quantifying threat level, besides over-emphasis on captive breeding recommendations. However, the revised Taxon data sheet (TDS) format overcomes this lacuna both by eliciting suggestions for in-situ management and making ex-situ conservation recommendations based less on genetics and more on purpose.

Red Listed Plants identified so far

Rapid threat assessment exercises carried out for 'some' of the species of conservation concern in southern and northern India, as per latest IUCN guidelines, have brought to notice around 200 medicinal plant species are under various degrees of threat. These exercises have not yet assessed all the species that are of conservation concern. It is estimated based on global rates of plant species threatened with extinction that around 1000 medicinal plant species may be under threat in different eco-systems across India. No threat assessment exercises for medicinal plants have how ever been carried out so far for central, western, eastern and north-eastern states.

 

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