POLLEN MORPHOLOGY OF THE NEW-ZEALAND SPECIES OF DACRYDIUM SOLANDER, PODOCARPUS LHERITIER, AND DACRYCARPUS-ENDLICHER (PODOCARPACEAE)

The pollen morphology of the New Zealand species of Dacrydium, Podocarpus and Dacrycarpus is described from observations made with the light microscope and scanning and transmission electron microscopes. An identification key is presented. Dacrydium pollen can be identified to the species level except for D. bidwillii and D. biforme which are inseparable. Podocarpus pollen is readily separated into 2 groups: (1) P. spicatus, P. ferrugineus; and (2) P. totara, P. nivalis, P. hallii, P. acutifolius, P. totara var. waihoensis. Further identification, especially within group 2, is difficult. Dacrycarpus dacrydioides pollen is easily identified because it is the only modern trisaccate type in New Zealand. A zone of exine differentiation termed region of weakness is identified in Dacrydium colensoi, D. intermedium, D. laxifolium, Podocarpus spicatus and P. ferrugineus. This region is adjacent to the proximal roots of the sacci at the lateral margins of the cappa and may function during periods of water stress, facilitating collapse and invagination of the sacci to protect the furrow.