南京地区繁缕和小繁缕群体的研究

A STUDY ON THE POPULATIONS OF STELLARIA MEDIA AND S. APETALA IN THE NANJING REGION

繁缕(Stellaria media)和小繁缕(S.apetala)是两个形态相似的近缘种,有人把后者作为前者的亚种或变种来处理。本文通过对南京地区不同生境的三个自然群体和三个人工控制栽培群体的取样,以群体为单位,分别测算了叶、萼片、雄蕊、花瓣、果实和种子的8个数量性状的变异,绘制了多角形图;对花粉粒和种子进行了扫描;还通过花蕾套袋试验对种子活力作了检查。结果发现繁缕和小繁缕都是近亲繁殖植物,在形态上区别明显,对生态环境的要求基本相同,但小繁缕似更能耐受人为的践踏和刈割。

Stellaria media (L.) Vill. and S. apetala Ucria are morphologically very similar, and the latter is treated by some authors as a subspecies or variety of the former. S. apetala is a native of Europe and Mediterranean Region and is reported in China for the first time.A comparative investigation of populations of the two species of the Nanjing region, Jiangsu Province, was carried out in order to shed some light on their biological interrelationships.Ⅰ. Quantitative measurements of morphological characters of 2 natural and 1 cultivated populations of S. media and 1 natural and 1 cultivated populations of S. apetala, including the length and breadth of leaves, sepals, fruits and seeds, the number of cilia per one side of the sepal, the number of stamens and petals, and the weight of 100 dry seeds, in order to evaluate the intra-and interpopulational variation of each species. The results are shown in Table 1 and Fig. 1.Ⅱ. Scanning electron microscopic observation of pollen grains and seeds of the two species.Ⅲ. Sheathing tests of flower buds and examination of the viability of seeds with a view to elucidate the mode of reproduction of the said taxa (Table 2).Ⅳ. Observation of environmental conditions of ecological sites of the populations. As a result of the above observations and experimentations, we have found that:Ⅰ. Both Stellaria media and S. apetala are inbreeders. Their intra-and interpopulational variation is insignificant.Ⅱ. The two taxa are morphologically very distinct and deserve specific ranks.Ⅲ. The two taxa are ecologically very similar, but S. apetala seems to be more endurable to trambling and mowing than S. media.