Aperture Orientation in Laurelia Pollen (Atherospermataceae Syn. Subfamily Atherospermoideae of Monimiaceae)

The development of the encircling aperture of pollen grains or the New Zealand species Laurelia novae-zelandiae is described by means of light and scanning electron microscopy. Some observations are also reported from pollen development and structure in the South American species Laurelia sempervirens, mature pollen of which can be distinguished from that of L. novae-zelandiae. The aperture begins to develop while pollen of L. novaezelandiae is still in tetrads, and passes through the distal and proximal poles of each grain. The widest parts of the mature aperture are at and near what are morphologically the distal and proximal poles of each grain. No such meridionosulcate type of pollen was recorded in a recent survey of pollen aperture types of primitive angiosperms and contradicts a recent report that pollen in the Atherospermataceae had equatorially aligned apertures.