Pharmacognostic and Taxonomic Studies of the Leaf of Ageratum houstonianum Mill. (Compositae)

Ageratum houstonianum occurs as a common agricultural weed, it is managed in small and large cropping situation by tillage and can contribute to soil fertility as a waste mulch. The aim of this study was to employ the pharmacognostic and taxonomic parameters to evaluate the leaves of Ageratum houstonianum. The leaves were collected, identified, air dried, pulverized and subjected to microscopy, micromeritics, chemomicroscopy, fluorescence, soluble-extractive values, moisture content and ash values using standard procedures. The result obtained from the microscopy showed an irregular epidermal cell shape and a sinuous anticlinal wall pattern, anomocytic type of stomata, double armed trichome and amphistomatic stomatal distribution on both the abaxial and adaxial surfaces. The stomatal index for the abaxial surface was 11.6% and for the adaxial surface was 25.6%.The micromeritic evaluation of the powdered leaf revealed a Carr’s index of 25.23%, Hausner’s ratio of 1.33 and an angle of repose of 38.8o indicating a poor flow. The result for chemomicroscopy showed the presence of oils, protein, lignin, mucilage and calcium oxalate crystals. For moisture content, the result was 12.7%w/w, the Total ash value was 14%w/w, Acid-insoluble ash value was 0.7%w/w,water-soluble ash value was 7.7%w/w, methanol-soluble extractive value was 17%w/w, ethanol-soluble extractive value was 16%w/wand the water-soluble extractive value was 21%w/w. The data obtained from the pharmacognostic and taxonomic studies provided information for the identity, quality and purity of Ageratum houstonianum.