Fevilleoideae pollen (cucurbitaceae): A study in striate ornamentation

Abstract

An exhaustive search into the Cucurbitaceae pollen literature and own observations were used to arrive at a sharper delimitation of the pollen of subfamily Fevilleoideae against that of the other subfamily, the Cucurbitoideae. Pollen data of 125 out of the 128 genera including all 19 Fevilleoideae genera were available. In view of a broad overlap, pollen grain size is not a reliable criterium to separate both subfamilies. Striate and microstriate ornamentation appeared to be very useful in identifying cucurbitaceous plants as Fevilleoideae. The perforate-rugulate type of Alsomitra is unique in the family. Gerrardanthus cannot be indicated as a member of the Fevilleoideae with pollen features alone, its relatively large (micro)reticulate pollen being similar to that of several Cucurbitoideae. On the basis of outgroup comparison, either striate or perforate-rugulate might be considered as the plesiomorphic ornamentation state in the family Cucurbitaceae. The (micro)reticulate type occurring commonly in the Cucurbitoideae evolved later, probably from a striate ancestral type and parallel to the (micro)reticulate type of the fevilleoid genus Gerrardanthus. The more or less striate (reticulate-striate) ornamentation found in seven genera in three Cucurbitoideae tribes probably evolved at least five times from (micro)reticulate ancestors. © 2010 Collegium Palynologicum Scandinavicum.