FREID, ETHAN. Department of Botany, Miami University, Oxford, OH 45056. - Stem, node, petiole, and leaf anatomy of Coccolobeae (Polygonaceae) and its systematic implications.
Stem, node, petiole, and leaf anatomy of Antigonon,
Brunnichia, Coccoloba, Muehlenbeckia, and
Podopterus was investigated. These genera have historically
been united within the tribe Coccolobeae. The tribe is interesting to
study because the genera form a heterogeneous group of taxa with
either winged achenes or drupes and habits that include vines, lianas,
shrubs, and trees. Forty anatomical features were compared across 39
species. Despite many similarities among the genera a number of
interesting patterns were observed. Anatomical trends that were
observed include variation in the presence of a stem endodermoid
layer, sclerenchyma, leaf trace divergence, and leaf trace pathways.
Petiole anatomy revealed differences in the vascular bundle
arrangement, and the presence of tanniniferous idioblasts, and
endodermoid layers. In leaves, there was variation in the presence of
tanniniferous idioblasts, prismatic crystals, leaf hypodermal layers,
as well as variation in venation patterns at the species level in
Brunnichia and Podopterus. The data suggests that
Coccolobeae may not be a cohesive evolutionary unit and contains
genera that would be best placed in other tribes.
Key words: anatomy, Coccolobeae, Polygonaceae, systematics, tribe