A TAXONOMIC STUDY OF THE GENUS TRIBULUS L. IN EGYPT II- HISTOLOGICAL FEATURES

Abstract

Comparative detailed vegetative anatomical investigation for stems, leaves and foliar details of the 7 studied taxa of the genus Tribulus in Egypt has been carried out in order to its reclassification based on internal structures. Accurate drawings for each of the studied organs are outlined into cumulative plates. Also an artificial in-dented dichotomous key has been constructed. Variation in number of basal vascular bundles (2 or 1) into the small leaflet-blade within the large leaf is utilized in classi-fying the studied taxa into two Groups. The 1st contained 5 taxa with 2 main bundles while the 2nd included 2 taxa each with single and unique basal bundle/small leaflet. Members of Gp.I are distinguished according to differences in : phloem & cambium characters, presence of 2 distinct glandular trichome types, stem outline & vascular cylinder contents, no. of petiolar vascular strands from base to apex, type of cuticle, type of pericyclic sclerenchymatous patches and others. On the other hand, variation in nature of starch sheath cells (from storing crystals to empty) and presence or ab-sence of schizogenous carnals in pith are found diagnostic in separating both mem-bers in Gp. II.

Keywords

• gennus tribulus l
• histological features