Abstract: Amentotaxus consists of three species distributed in southern, central, western mainland and southern Taiwan of China. Its pollen grains were examined by LM, SEM and TEM. The pollen grains of this genus are suhsphaeroidal, sometimes suboblate or irregular, 27.8 μm to 45.4 μm in diameter, at tenuate towards distal pole. It is worthy of note that a number of pollen grains in Amentotaxus argotaenia possess relic saccuses. The exine surface conrains tuberculate ornamentation of two sizes, i,e. sparse and coarse tuberculae and rather dense and fine tuberculae under SEM. TEM examination reveals that endexine is of lamellate structure containing 7-9 lamellae. Ectexine is composed of tectum, granulate layer and food layer. Tectum is very irrigular, consisting of tuberculae which are linked up forming strings of beads or fused into a number of masses. The granulae of granular layer under the tectum are distributed in heaps. These granulae are easily fallen in some cases. The foot layer is made of 1-2 thick and dark lamellae which are as dark as the tectum and possess tripartite structure, i,e. with a central white line and coarse and dark lines on both lateral sides. But lamellae of endexine are thin and light and have no tripartite structure. Ultrastructure of pollen exine of Amentotaxus is obviously distinguished from that of Taxaceae and Cephalotaxaceae. The characteristics of ultrastructure of pollen exine in Amentotaxus support its being seperated from Taxaceae and treated as an independent family, Amentotaxaceae.

Key words: Amentotaxus, Amentotaceae, Pollen exine, Ultrasructure