Anatomical Studies of the Midrib, Petiole and Epidermal Strip of Some Vernonia Species, from Nigeria

U. Asuzu Chinwe

Background and Objectives: Leaf epidermal strip, transverse sections of midrib and petiole of five species of Vernonia from South-eastern Nigeria namely; Vernonia ambigua, Vernonia amygdalina (bitter forms), Vernonia amygdalina (non-bitter forms), V. cinerea and V. glaberrima were examined using a calibrated motican microscope to determine leaf epidermal cell and other leaf anatomical features of taxonomic importance. V. glaberrima is famed as a very potent anti-malarial plant, though it grows in the wild, it is often spared during bush clearing. Vernonia ambigua and V. cinerea are both used as medicine though they are regarded as weeds. Vernonia amygdalina (bitter and non-bitter) grow in homestead as vegetable(readily available all the year) and as medicine for various ailments. Part of the aim of this study was to examine anatomical differences between these two forms towards contributing to the determination of their varietal or species status. Materials and Method: Epidermal preparation of freshly collected leaves together with transverse sections of the midrib and petiole were made. Results: Variations were observed among the species in their stomatal index, midrib and petiole outline, number of layers of collenchyma, number and shape of vascular bundles, shape of anticlinal walls in both adaxial and abaxial epidermis and guard cell dimensions. Marked differences were observed in the epidermal strips of the bitter and non-bitter varieties of V. amygdalina. It is suggested that DNA test should be carried out to determine if the two should be given species status. Conclusion: Anatomical features of the midrib, petiole and epidermal strip provided sufficient data to separate the species of Vernonia studied.

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