PALYNOLOGY AND SYSTEMATICS OF THE LYTHRACEAE. II. GENERA HAITIA THROUGH PEPLIS

Pollen morphology for 12 genera of the Lythraceae is described, using light microscopy (LM), scanning (SEM) and transmission electron microscopy (TEM). The genera surveyed are Haitia, Heimia, Hionanthera, Lafoensia, Lagerstroemia, Lawsonia, Lythrum, Nesaea, Orias (= Lagerstroemia), Pehria, Pemphis, and Peplis. Among results of taxonomic significance are 1) the similarity of pollen between Haitia and Ginoria, suggesting that future classifications reflect a close relationship between these genera, 2) a comparable similarity in pollen between Pehria and Adenaria, 3) the distinction of Hionanthera pollen from that of Ammannia, 4) an exine similar in certain ultrastructural characteristics between Orias and some species of Lagerstroemia, although in general aspect they appear quite different, 5) that within the Didiplis-Lythrum-Peplis complex, there are three palynologically distinct groups, with Didiplis standing apart from the somewhat more similar, but nevertheless, distinct Lythrum and Peplis, and 6) that considerable differences exist between pollen of Pemphis acidula and Pemphis madagascariensis, supporting removal of the latter species to a new genus. This pollen survey is part of a multi-disciplinary effort to clarify generic limits in the Lythraceae, and evaluate relationships within the family and among families of the Myrtales.