Research Training Program

This project involved a comparison of the leaf anatomy of Aneilema zebrinum, formerly the genus Ballya, with twelve of the fourteen species in Aneilema section Lamprodithyros and a construction of a phylogeny for the section based on morphological and anatomical characters. The reclassification of Aneilema zebrinum as Ballya zebrina was originally based on floral and vegetative morphology and was later supported by anatomical data. Anatomically, Ballya was distinguished from Aneilema by the presence of an elongate leaf epidermal layer, glandular microhairs with a distal cell longer than the middle cell, and microhairs with an indistinct basal septum. It was determined that Ballya was indistinct from Aneilema since epidermal elongation was found in three additional species of section Lamprodithyros, the distal cells of the microhairs were comparable to those in Aneilema, and the basal septa were equally distinct. Given these findings, the phylogenetic relationships were inferred among the species in the section and found that Aneilema zebrinum was firmly rooted in section Lamprodithyros and that the epidermal elongation may have evolved twice. The dual origin of epidermal cell elongation is interesting since all other genera in the Commelinaceae achieve succulence through the thickening of a hypodermic, rather than the elongation of an epidermis. These unique features support earlier hypotheses that section Lamprodithyros is one of the more derived groups in Aneilema.