穗花杉属花粉外壁的超微结构及其分类意义

本文用光学显微镜、扫描电镜和透射电镜观察了穗花杉属Amentotaxus Pilger花粉外 壁表面和内部的超微结构，并叙述了本属与红豆杉科Taxaceae和三尖杉科Cephalotaxaceae花粉形态的区别。根据花粉外壁超微结构资料，论述了该属的分类位置。

Ultrastructure of Pollen Exine in Amentotaxus Pilger and Its Significance in Taxonomy

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 num- ber of pollen grains in Amentotaxus argotaenia possess relic saccuses.  The exine surface con- rains 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 structu- re 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 distri- buted 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 en- dexine 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 chara- cteristics of ultrastructure of pollen exine in Amentotaxus support its being seperated from Ta- xaceae and treated as an independent family, Amentotaxaceae.