CLADISTIC-ANALYSIS AND POLLEN EVOLUTION IN ANNONACEAE

To evaluate hypotheses on pollen evolution in Annonaceae, we present a cladistic analysis, using both palynological and non-palynological characters, and including other Magnoliales as outgroups. As previously proposed, the inferred basic pollen type is single (monads) and monosulcate. with granular infratectal structure (interstitium), but with a few nexinal foliations. Permanent tetrads originated in two major lines: the xylopioids, corresponding to part of Walker's Fusaea subfamily but excluding Fusaea. with granular structure and a nexine of fused granules; and the annonoids, corresponding to Walker's Annona subfamily, with columellar structure and a complexly foliated nexine. The single grains of lsolona are secondarily derived from tetrads. Sulculate pollen arose in both monosulcate and inaperturate lines. The genus Polyalthia, which has unusually diverse pollen, appears to be polyphyletic. Columellar structure originated in smooth monosulcates with granular structure, leading to the malmeoids, and in forms with larger, irregular granules, in the disulculate Polyalthia group and possibly the annonoids.