The biological and logical meaning of trees, which are one of the important woody plants of our ecosystem, are reviewed in this article. Trees are mostly used for timber purposes, but in the present article the utility of trees with respect to their importance in restoring, reclaiming and rejuvenating denuded and disturbed soils, their ecological, ecodevelopmental and environmental use, and their educational and recreational value in gardening, landscaping and bioesthetic planning is described. In addition, the importance of trees is discussed with reference to their value as a source of sustenance: food, sugars, starches, spices and condiments, beverages, fumitories, masticatories and narcotics, medicines, essential oils, fatty oils and vegetable fats, waxes, soap substitutes, vegetable ivory, fodder, fuel, bioenergy or biofuel, fertilizers, fiber, pulp and paper, tannins, dyes, rubber and other latex products, gums, resins and cork. Lastly, the food plants of mulberry and non-mulberry silkworms, which feed on the leaves of many forest trees, are mentioned.

Many plants take up soluble monosilicic acid from the soil. Some of these plants subsequently deposit it as cell inclusions of characteristic structure. This article describes the distribution and diversity of opaline silica bodies in monocotyledons in a phylogenetic framework, together with a review of techniques used for their examination, and the ecology, function and economic applications of these cell inclusions. There are several different morphological forms of silica in monocot tissues, and the number of silica bodies per cell may also vary. The most common type is the “druse-like” spherical body, of which there is normally a single body per cell, more in some cases. Other forms include the conical type and an amorphous, fragmentary type (silica sand). Silica bodies are most commonly found either in the epidermis (e.g., in grasses, commelinas and sedges) or in the sheath cells of vascular bundles (e.g., in palms, bananas and orchids). Silica-bearing cells are most commonly associated either with subepidermal sclerenchyma or bundle-sheath sclerenchyma. Silica bodies are found only in orchids and commelinids, not in other lilioid or basal monocots. In orchids, silica bodies are entirely absent from subfamilies Vanilloideae and Orchidoideae and most Epidendroideae but present in some Cypripedioideae and in the putatively basal orchid subfamily Apostasioideae. Among commelinid monocots, silica bodies are present in all palms, Dasypogonaceae and Zingiberales but present or absent in different taxa of Poales and Commelinales, with at least four separate losses of silica bodies in Poales.

Vigna radiata (L.) Wilczek, popularly known as “mung bean,” is an important protein supplement in vegetarian diets in many countries of Asia. It has a short life cycle (55–70 days) and fits well into many cropping systems, including rice and sugarcane, under rain-fed and irrigated conditions. The present review deals with the data available on plant regeneration of this species. Both shoot-tip multiplication and somatic embryogenesis have been compared on the basis of retrospective as well as recent reports. Molecular markers, especially random amplified polymorphic DNA (RAPD), have been used to compare results obtained from in vitro and in vivo studies on various species of Vigna. Isozyme markers such as esterase and superoxide dismutase, which are expressed during in vitro regeneration and in vivo development of Vigna species, are also included in this article.