Studies on morphology and anatomy of Strychnos spinosa Lam. (Loganiaceae)

Abstract

Strychnos spinosa Lam. belongs to the family Loganiaceae.  It is a small tree.  The morphological and anatomical features of the leaves, stem, flower and fruit were studied. S. spinosa has a cylindrical stem with a pair of spines at irregular spaces. The leaves are opposite, decussate, petiolate with palmate venation. The petals are greenish in colour, tubular with five lobes. There are numerous white hair-like appendages at the neck of the corolla tube. The androecium is epipetalous and attached close to the bottom of the corolla tube. The flower is a cyme, occurring in threes, with the middle one being the oldest. The fruit is a berry with very hard pericarp. It turns from light green when unripe to bright yellow when ripe. The anatomy of the leaf revealed presence of rosette crystals and intraxylary phloem which is more pronounced in the mid rib and petiole. “Kranz” structure was observed in the transverse section of the leaf. Anisocytic stomata are numerous in the abaxial (lower) epidemis but absent in the adaxial epidemis. The anatomy of the stem showed the presence of crystals in the cortex. Both solitary and multiple vessels are found in the transverse section.  In the tangential longitudinal section, most of the rays were four to seven cells wide, but a few were uniseriate, biseriate and triseriate. Most of the pollen grains were triangular in the polar view but a few were quadrangular. Those that were triangular exhibited tricolporate aperture while those that were quadrangular had tetracolporate aperture. The sculpturing was perforate and were not very compact.   Key words: Strychnos spinosa, rosette crystals, intraxylary phloem, pollen dimorphism, heterogenous, rays.