Primitively columellaless pollen: a new concept in the evolutionary morphology of angiosperms.

Comparative study of pollen of the ranalean complex has revealed a remarkable, hitherto unrecognized characteristic of primitive angiosperm pollen, namely, its complete lack of columellae. Pollen with such exine has been desnated atectate anid taxa in the Magnoliaceae. Degenzeriaceae, Eupomatiaceae, Annonraceae, and possibly Himantandraceae and Nymphaeaceae have pollen which is considered to be primitively columellaless.