POLLEN MORPHOLOGICAL STUDIES OF FAMILIES OF MALVACEAE
The pollen features of some sterculia species belonging to the family malvaceae were investigated after acetolysis.
Their qualitative and quantitative features were determined by Light Microscope (L.M) in order to identify the observed external and internal peculiarities with respect to their taxonomic implications. In the general characteristics of malvaceae,these species were cola acuminata, cola Nitida, Hibiscus sabdariffa (Linn), urena lobata (Linn) and Abelmoschus esculentus.
Results showed great significant variations in most of the features. Pollen grains were dicolpate, tricolpate and ornamentation were scabrate in 3, were cola acuminate and cola Nitida was reticulate. Urena lobata had the highest size in equatorial view length (9.5±0.187).
There was no significant differences. The pollen shapes were spheriodal in all the species. While pollen shapes in polar view were circular for all. The result showed that they are more closely related. The species have great similarities hence their grouping under the same genus.
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.
1.1the 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.