摘要
在光镜和扫描电镜水平上系统观察了豆科黄华族3属13种植物的叶解剖和叶表面特征。结果表明沙冬青属(Ammopiptanthus)具全栅型叶肉组织、簇生型盲脉、环列型气孔器以及独特的毛状体,与黄华属(Thermopsis)和黄花木属(Piptanthus)明显不同。后两属具有双栅型或正常中生型叶肉、非簇生型盲脉、无规则型或无规则四细胞型气孔器及丝状表皮毛等,表明二者间有较密切的联系。这些特征进一步证实沙冬青属是本族中一个较孤立和原始的类群。同时,叶肉组织的分化,气孔器与毛状体的密度和分布,角质层及蜡质纹饰等特征说明本族植物有趋于旱化的趋势;不同种类对其分布区不同气候条件的适应可能构成了相互间主要的隔离机制;中亚地区的荒漠化以及青藏高原隆起引起的气候的旱化和寒化作用可能是本族植物主要的演化动力之一。
Anatomical characters of leaves of Chinese species of the tribe Thermopsideae, including 3 genera and 13 species, were compared. The results show that the differentiation of mesophyll cells, stomatal types, stomatal distribution and density, shape of epidermal cell, trichome shape and density, cuticular membrane and waxy ornamentation have important systematic and ecological significance among the genera of the tribe. With regard to leaf architecture, pollen morphology and external morphology studies, we suggest that Ammopiptanthus represents an isolated and primitive genus in the tribe and Piptanthus is closely related to Thermopsis. Although different vein-endings, stomatal types and trichomes indicate systematic differences, other characters, such as mesophyll type, stomatal distribution, trichome density etc. are the result of ecological adaptation among the genera. Results of the present study confirm our previous conclusion that two evolutionary trends exist in the tribe, the first towards erophilization and the second towards cold-adaptation They are caused by the desertification of the central Asian area and the heave of intermountainous plateau. Ecological isolation may be a main evolutary motivation among the taxa in the tribe. We have observed that stomatal density and size in the xeromorphic genus, Ammopiptanthus, are not simply a result of the general trend in xerophytes to have high stomatal density correlating with the relatively small size. On the contrary, stomata in this' genus are larger than those in the mesophytic genus, Piptanths, and the density on the lower surface is much less than in the latter. However, stomatal density on the upper surface follows the trend in concordance with increasing aridity and altitute.
基金
国家自然科学基金部分资助
关键词
豆科
黄华族
叶
解剖
系统学
生态
Leaf-anatomy
Leaf-surface
Systematics
Ecology
Thermopsideae
