宝盖草的繁育系统

BREEDING SYSTEM OF LAMIUM AMPLEXICAULE

宝盖草(Lamium amplexicaule L.)具两种类型的花:短花冠的闭花授粉的花和长花冠的开花授粉的花。本文研究了在3个不同生态环境的自然群体中这两种类型花的数量和开花时间的变化,并通过套袋试验,种子萌发试验和刈割试验,获得了有关开花节律和生活周期以及与环境条件和人类干扰的关系的结果。宝盖草的种子绝大部分是自花授粉的产物,但也有一定程度的异花授粉。自花授粉有利于开拓新的定居环境,而异花授粉则使后代能适应多种环境条件,而这两种授粉方式的结合是使宝盖草成为一种成功的杂草的主要因素。

Lamium amplexicaual L. (Labiatae) possesses two types of flowers on the same plant: self-compatible (short-tubed, closed, weakly pigmented and self-polliuating) cleistogamic flowers and self-incompatible (long-tubed, open, showy,and insect-pollinated) chasmogamic flowers. In natural populations, however, cleistogamie flowers are abundant while ehasmogamic flowers are sporadic. The paper recorded the breeding system of Lamium amplexicaule and discussed its relevance to the life cycle and ecological environments of the species. By so me tests, such as sampling of natural populations,sheathing tests,seed germination tests, and mowing tests,the auther found the principal results:its rhythm of flowering, life cycle,method of reproduction and germination of seeds,and concluded that Lamium amplexicaule,being a successful weed, is probably due largely to its mixed selfing and outbreeding system. The abundance of cleistogamic flowers of the plant assures reproduction in rigorous environments and disturbed conditions, but loses the evolutionary potential based on variation. In the meanwhile the occurrence of a small number of chasmogamic flowers will make a compensation of genetic variability for the losses in inbreeding.