禾本科植物幼苗与进化关系的研究

GRASS SEEDLINGS AND THEIR EVOLUTIONARY RELATIONSHIP

本文以禾本科植物幼苗基本特征和基本类型为基础对禾本科植物各类群的进化关系进行了探讨。原始禾本科植物幼苗第一叶宽短．中胚轴仲长，不具中胚轴根，不具质片及胚根鞘节根，县少数或不具胚芽鞘节根。现代禾本科植物各亚科不同的幼苗类型是在原始幼苗的基础上直接或间接进化来的。各亚科及内部各种幼苗类型的进化顺序及地域分布反映了各类禾本科植物从其原发地向各自分布地扩散、迁移和进化适应的过程。

According to basic characters and basic types of grass seedlings, evolutionaryrelationships of grass groups are studied in'this paper. The ancestral grass seedlingmorphological shapes were: the first leaf broad and short, the mesocotyl elongative,the mesocotyl roots absent, the sculletum and coleorhiza node roots absent, thecoleoptile node roots a few or absent. The modern seedling types of each subfamilytvers directly or indirectly evoluted frpm ancestral grass seedlings. Evolutionarytrends were from broad and short to narrow and long for the first leaf, fromlacking to appearing and increasing for the mesocotyl roots. the coleoptile noderoots and the sculletum and coleorhiza node roots. The evolutionary order anddistribution of the grass seedling types between and within subfamilies showed thegradual spread, migration and adaption of every grass groups from their originalplace to their distributive place.