Indian sub-continent is a rich source of plant and animal wealth, which is due to its varied geographical and agro-climatic regions. Besides it's varied biodiversity, it has a diverse cultural heritage too. Though at present Indian health care delivery consists of both traditional and modem systems of medicines, both organized traditional systems of medicine like Ayurveda, Siddha and Unani and unorganized systems like folk medicine have been flourishing well. Ayurveda and Siddha are of Indian origin and accounted for about 60% health care delivery in general and 75% of rural Indian population depends on these traditional systems. These two systems of medicine use plants, minerals, metals and animals as source of drugs, plants being the major source. It is estimated that roughly 1500 plant species in Ayurveda and 1200 plant species in Siddha have been used for drug preparation (Jain, 1987, Krishnakumar and Sureshkumar, 1995). In Indian folk medicine use, about 7500 plant species are recorded as medicinal plants (Anonymous, 1996). Though the Indian traditional systems of medicine are time-tested and practiced successfully from time immemorial, there is lack of standardization with regard to identity of crude drugs, methods of preparation and quality of finished products.
Textual variations exist among the innumerable literatures on traditional medicine on the constituents of a drug, methods of preparation and the names of medicinal plants. Multitude of vernacular names of medicinal plants found in the literatures pose problems in identifying the correct botanical names of medicinal plants. And, it is worst confounded with the use of different vernacular names, for the same plant, in different localities in the country. Vernacular names of some medicinal plants whose botanical identity are not known or ambiguous, find place in standard formularies and pharmacopoeia (Example: 'Avilthol’ and 'Kiliyooral' have no botanical identity (Anonymous, 1972) and for the Sanskrit name 'Punarnava' two plants Trianthema portulacostrum, and Boerhaavia repens are mentioned (Mukerji, 1953).
Standardization of herbal drugs is most desirable at this time when world- wide interest on herbal medicine has gained momentum. Besides lack of standardization, unscrupulous commercial practice of adulterating and substituting the genuine herbal drugs are posing great hurdle in popularizing the time-tested herbal-based traditional medicine. To achieve WHO's proclamation of "Health for all by 2000 AD" traditional medical systems have to be strengthened and popularized within the shortest possible time. Standardization of herbal medicine has the key to achieve this aim.
Pharmacognosy - tool for crude drug standardization
The term pharmacognosy is derived from two Greek words 'Pharmacon' meaning drug or medicine and 'gnosis' knowledge. C.A. Seydler first coined this term in his dissertation entitled 'Analecta pharmacognosia' in 1895. Pharmacognosy is closely allied to medicine, developed during early nineteenth century as a branch of Materia Medica and applied biology. It is a study of drugs having their origin in plant and animal kingdom. The subject pharmacognosy can also be expressed as an applied science that deals with biological, biochemical, therapeutic and economic features of natural drugs and their constituents. Tyler et al. (1981) defined that in a broad sense, pharmacognosy embraces knowledge of the history, distribution, cultivation, collection, selection, preparation, commerce, identification, evaluation, preservation and use of drugs and economic substances that affects the health of men and other animals.
In the earlier days, only the external morphological characters were used to identify a drug. As late as the beginning of the present century, pharmacognosy had developed mainly on the botanical side, being particularly concerned with the description and identification of drugs both in their whole state and in powder form. Modem aspects of pharmacognosy include not only the crude drugs but also their natural constituents and their derivatives.
Like other biological sciences, pharmacognosy has utilized related fields to bridge the transition from a descriptive science to a functional science. Various pharmacognostical methods are evolved to standardize crude drugs. Therapeutic efficacy of medicinal plants depends upon the quality and quantity of chemical constituents. It has been established that chemical constituents of a plant species vary With regard to climate and seasons (Tyler et al., 1981). A plant species grown in different geographical localities also show quantitative variation in their chemical constituents (Mallavarapu
et al., 1995). Variation in biological compounds exists not only in species level but also in variety and cultivars levels too. Many varieties within a species might show variations in histological and phytochemical aspects. These differences exist among varieties of commonly occurred medicinal plants. These variations might be climatic, altitudinal, geographical or genetical in nature. Many varieties of medicinal plant species are found in nature. Though pharmacognostical studies on individual medicinal plants, their constituents and their efficacious have been undertaken, little work has been done on comparative analysis of the variations in morphological, phytochemical and pharmacological aspects of varieties of medicinal plants. And to fulfill this gap, the present work is undertaken with a view to analyze, similarities and dissimilarities in morphological, anatomical, microscopical, physicochemical and phytochemical characters of the following varieties of plants. These plants are commonly available and medicinally useful in this geographical area and this study would form a foundation for understanding the pharmacological and therapeutical effectiveness of these varieties.
Cissus quadrangularis L. (Square-stemmed)
C. quadrangularis L. (Round-stemmed)
C. quadrangularis L. (Flat-stemmed)
Madhuca longifolia (Koen.) Macbr. var. longifolia.
M. longifolia var. latifolia (Roxb.) A.Cheval
Basella alba L. var. alba Wight.
B. alba L. var. rubra. (L.) J.L.Stewart.