SYSTEMATICS OF THE LEMNACEAE (DUCKWEEDS) - INFERENCES FROM MICROMOLECULAR AND MORPHOLOGICAL DATA

Diminutive plants of the duckweed family have been difficult to study systematically because of reduction and character state losses that ha ve accompanied their adaptation to aquatic habitats. Phylogenetic anal ysis of flavonoid and anatomical-morphological data indicate that evol ution in the family has proceeded in a linear manner from complex ance stors to reduced species of subfam. Wolffioideae. The high probability of convergence for character reduction and loss, however, renders thi s conclusion tentative. Cladograms from combined data require only a s light increase in length to resolve all four genera as monophyletic. T hese studies indicate the need for more suitable data to evaluate hypo theses of duckweed relationships.