Pollen morphology of atherosperma, daphnandra and doryphora (atherospermataceae [monimiaceae])

Abstract

Atherosperma moschatum Labill., Daphnandra micrantha (Tul.) Benth. and Doryphora sassafras Endl., of the family Atherospermataceae (syn. subfamily Atherospermoideae of the Monimiaceae) of the Laurales, have medium‐sized, isopolar, globose to globose‐ellipsoidal pollen grains. The pollen is either dicolpate, with two elongated apertures centered at the poles (Doryphora) or meridionosulcate, with a median encircling aperture which narrows markedly (Atherosperma) or less markedly (Daphnandra) in equatorial regions. Exine is tectate‐columellate with an uneven foot layer of partly‐fused, large, irregular sized, granules. Traces of white line centered lamellae, characteristic of some members of the subfamily Monimioideae of the Monimiaceae, were found within the foot and columellar stratum of Atherosperma. An endexine is probably absent. In apertural regions exine processes are reduced in size and form clusters which are separated by smooth regions where exine seems to be almost completely lacking. In Atherosperma and Doryphora the intine comprises two zones—an outer channelled zone and a thinner inner zone of more conventional appearance. In Daphnandra there is a thin homogeneous zone too outside the channelled zone, of similar appearance to the innermost zone of the intine. The intine, especially the channelled zone, is thicker in apertural regions. It is concluded that although pollen of the Atherosperma group shows some links with other Monimiaceae (sensu lato), it is sufficiently distinct, particularly in having tectum, columellae and foot strata, as to support the existence of the Atherospermataceae as a separate family.