Root anatomical studies on Solanum macrocarpum and Solanum nigrum (Solanaceae)
The anatomical characteristics of the roots of Solanum macrocarpum and Solanum nigrum were investigated to ascertain the relevance of these characters in establishment of interspecific similarities and differences in these two taxa. The results showed that there is concentration of vascular bundles at the central portion of the root cortex hence the endodermis is not well differentiated in both taxa. Again the epidermal cells are big and well differentiated in S. macrocarpum but small and well differentiated in S. nigrum. The epidermal cells range from pentagonal to hexagonal in S. macrocarpum but irregularly shaped in S. nigrum. The cells outside the cortex are thick and big in S. macrocarpum but thin, small and elongated in S. nigrum. Although, the size and number of vascular bundles are small and few in both taxa, the presence of one or two oxalate crystals that characterized S. macrocarpum but absent in S. nigrum is an interesting aspect of the root anatomy. The similarities in structures showed reasons for the two taxa to be in the same genus while the differences in root anatomical structures showed reasons for them to be as different species.