Pollen types in the lauraceae

Pollen morphology of southern African Lauraceae (Cassytha, Cryptocarya, Dahlgrenodendron, Ocotea) and members of the genera Beilschmiedia, Eusideroxylon, Hypodaphnis, Lindera and Potoxylon was studied by means of light and scanning electron microscopy. Pollen morphologically the various genera could readily be distinguished from each other, but few interspecific differences were found. To assess the taxonomic significance of pollen characters in Lauraceae, evidence from the literature was also considered and compared with the infrafamilial classification proposed by Kostermans. On the basis of mainly shape and exine sculpture, four pollen types are distinguished in Lauraceae. Pollen type A (grains spheroidal, apolar, spinulose) has been only recorded in the tribes Perseeae, Cinnamomeae, Litseeae and Hypodaphneae; pollen type B (oblate/peroblate, isopolar, slightly to strongly verrucate) occurs only in the Cryptocaryeae; pollen type C (spheroidal, apolar, strongly verrucate/spinuloid) is characteristic of the subfamily Cassythoideae, whereas pollen type D (spheroidal, para-isopolar, striate) is known only in Dahlgrenodendron, a monotypic genus and perhaps best placed in a tribe of its own. Hence each of the tribes proposed by Kostermans (1957) proved to be homogeneous as to pollen type. Detailed analyses of the shape and surface ornamentation of lauraceous pollen grains hold considerable promise as a potential source of taxonomic evidence to be employed on the generic and higher levels.