The evaluation of the cultural significance of plants in ethnobotanical studies is an essential step in various types of investigations, including research on lexical retention of plant names in diverging languages, on trade and material exchange between groups, on subsistence strategies, and in folk classification. The reciprocal nature of the relationships between humans and plants is recognized today as integral to the study of ecological anthropology, cultural ecology, and ethnobotany.
Most developing countries are situated in the inter-tropical zone, with especially rich and diversified flora which constitutes an important reservoir of the world's bio-diversity. It is thought that the tropical forests contain approximately half of the world's species.
In most developing countries of the South, more than 80% of the population relies on plant and animal based medicines to meet their health care requirements. For the most part, the plants and animals used in traditional medicine are collected from the wild, and in many cases, demand far exceeds supply. As the population grows, demand for traditional medicines will increase, and pressure on natural resources will become greater than ever.
Many medicinal plants from the South are also valued in selected markets around the World. The growing demand for natural cosmetics, and herbal and prescription medicine, has resulted in significant imports of wild plants to developed countries. At the same time, very little information exists on the local knowledge pertaining to bio-diversity conservation and management and on the identity of many species in trade, the volumes traded and the impact of harvest.
The Huastec Indians of northeastern Mexico have an elaborate botanical knowledge of the biological, physical, and chemical properties of available plants in their rainforest environment. Plants are used by the Huastec for firewood, construction, and medicinal purposes. An example is 'papaloquelite', the Mexican common name for various taxa of the genus Porophyllum. The use of these plants dates from at least 500 years ago and at present they are used as medicine and food.
Martyniaceous plants are used in the many parts of world in which they grow. In Mexico, seeds, roots and leaves of species of Proboscidea are gathered and consumed as food. Leaves of Martynia are used to remove insects from fowl in Mexico and Guatemala, and its fruits are used medicinally in the former country. Most Mexican common names for martyniaceous plants are descriptive, and the folk taxonomies for these plants often agree with scientific taxonomies. The showy and fragrant flowers and oddly-shaped fruits of Proboscidea, Ibicella and Martynia led to their cultivation as ornamentals in the United States and Europe. The common names of martyniaceous plants in European languages are generally variations of devil's claw, cat's claw, or unicorn plants. Devil's claw has been used in basketry and ritual by Pueblo cultures and other native American groups. in the Southwest. Young fruits of Proboscidea and Ibicella are eaten as vegetables and pickles in the United States, South America, and Europe. Mature fruits of Craniolaria are consumed as food or medicine in South America and the Antilles.
Tribes of Totopara and adjoining areas in Jalpaiguri District, West Benegal (India) have a complicated ethnobotany. 84 species of angiosperms are predominantly used by the tribes inhabiting these areas (Totos, Mech, Modesia, Nepalese, etc.), for food, for poisoning fish, as medicine, fodder for cattle, and other needs.
Polynesian cultures owe their longevity and stability to their ability to exploit natural plant resources to provide food, shelter, clothing, and medicine. Technologies involving indigenous plants have been highly developed. This includes traditional food preservation technology, such as two Samoan technologies for breadfruit and banana preservation.
Knowledge concerning wild plants and their uses was up until a few generations ago an essential part of life for the inhabitants of Manang District (Nepal-Himalaya). On the one hand, numerous plants served to supplement the alpine region's very limited food resources while on the other hand they were indispensable in the treatment of various diseases. Moreover, wild plants, particularly medicinal herbs, have for generations been counted among the most important trading products and in addition have had throughout a decisive role to play within the material culture as well as in the religious-ritual context. At present the empirical knowledge accumulated by experience and handed down over generations is in the process of dying out. As a result of the introduction of new plants for cultivation (e.g. potatoes, winter wheat, vegetables), the increasing distribution of chemical-based medicines (by the local health posts), the opening of markets to the products of 'Western civilization' (aluminium and plastic ware etc.) and the improvement of the general economic situation, traditional plant lore is losing ever more of its significance (not only in Manang District). Running counter to this development, however, is the increased interest taken by various sciences (e.g. botany, pharmacology, ethnology, geography) in traditional folk wisdom, so that for a number of years now the attempt has been made to return to the sources of traditional plant lore in order to record and document the treasure of knowledge that still exists.
The Kumaon Himalaya in India is a mountainous region inhabited mainly by the Bhotia, Jadh, Khasia, Dom and the Raji tribes, or groups. They utilize numerous indigenous plants for medicine; 41 more important species are used to treat approximately two dozen different ailments. These species are also used as: dyes, incense, insecticides, piscicide, masticatory meat tenderizer, spice, etc., and have associated beliefs and taboos.
The contributions of ethnobotanists are particularly valuable because they can find where and why useful wild species persist in agroecosystems. A greater effort to direct the attentions of policy makers to the value of ethnobotanical knowledge is needed.
Ethnobotany is becoming increasingly important in the curing and prevention of modern day ailments. This knowledge is becoming limited due to the extinction of species and loss of knowledge from traditional healers. Western doctors are now trying to regain and retain the knowledge that can be provided by indigenous medicines and healers.
The possible uses of medicinal plants to treat various conditions have been widely documented. However, knowledge regarding the stage at which plants provide the best material, the locations where they are available, how they may be harvested with minimal destruction, etc., are not clearly found in the manuscripts. If this knowledge dies with elderly practitioners, it may in fact be lost forever.