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 ch aracters, and including other Magnoliales as outgroups. As previously proposed, the inferred basic pollen type is single (monads) and monosu lcate. with granular infratectal structure (interstitium), but with a few nexinal foliations. Permanent tetrads originated in two major line s: the xylopioids, corresponding to part of Walker's Fusaea subfamily but excluding Fusaea. with granular structure and a nexine of fused gr anules; 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 pol len arose in both monosulcate and inaperturate lines. The genus Polyal thia, which has unusually diverse pollen, appears to be polyphyletic. Columellar structure originated in smooth monosulcates with granular s tructure, leading to the malmeoids, and in forms with larger, irregula r granules, in the disulculate Polyalthia group and possibly the annon oids.