POLLEN MORPHOLOGICAL STUDIES OF SOME FAMILIES OF MALVACEAE
Malvaceae or the mallow family is a family of flowering plant containing over 200 genera with close to 2300 species (Judd and Manchester, 1997). The largest genera in term of number of species include pavonia (200species), sida (200 species), Dombeya (225 species, sterculia (250 species) and Hibiscus (300 species).
Popular plants of the family malvaceae are generally valued for commercial cotton, gorgeous spring blossoms and some for their colourful foliage. It is a globally distributed family with primary concentrations of genera in the tropical and subtropical regions (Hutchinson, 1967; Fryxell, 1975, 1988, 1998; Heywood, 1993; La Duke and Doeby, 1995; Mabberley, 1997).
Most species of malvaceae are herbs or shrubs but some are trees and lianas. Leaves are generally alternate, often palmately lobed or compound and palmately veined. The margin may be entire, but when dentate a vein ends at the tip of each tooth (malvoid teeth). Foliacious stipules are present and the stem contains mucous canals and often also mucous cavity. Hairs are common, and are mostly typically stellate.
Flowers are commonly borne on indefinite axillary inflorescences, which are often reduced to a single flower, but may also be cauliforous, oppositifolious or terminal. They can be unisexual or bisexual and generally actinomorphic, often associated with conspicuous bracts, forming an epicalyx. They generally have five valvate sepals, most frequently basically connate and five imbricate petals.
The stamens are five to numerous, connate at least at their bases, but often forming a tube around the pistils. The flowers have nectarines made of many tightly packed glandular hairs, usually positioned on the sepals. Fruits are often a loculicidal capsule, schizocarp or a nut.
Due to the high economic value of many taxa of malvaceae (Gossypium, Hibiscus, Abelmoschus and malva), several studies of different perspective have been carried out (krebs, 1994, Ray, 1995, 1998; Hosni and Araffa, 1999).
The principle economic uses of malvaceous plants is as a source of natural fibers, the family providing perhaps the worlds 3 most important fibre crops. Plants of the family are also used for food, beverages, timber, in traditional medicine and in horticulture.
Abelmoschus esculentus is used as vegetable and also have medicinal uses such as treating fevers, gonorrhoea, dysentery, catarrhal infections, emollient, antispasmodic and tonic.
The major objectives of the study were
(1). To determine the micro-morphological features of the pollen of these species.
(2). To highlight the morphological variability’s
(3). To evaluate the taxonomic significance of the pollen features, variations.