Taxonomical Study On Astragalus In Qinling Range

In this paper we dealt with the taxonomy of the genus Astragalus in Qinling Range, China. The main results are as follows:1. According to filed research and herbarium study, there are 32 species of the genus Astragalus in this area, including one subspecie and three varieties. Of which fourteen were not included in Flora Tsinlingensis. A key to these plants, the description of characteristics and geographical distribution of them were also given.2. The similar morphology of tubular calyx tube and linear pods in A.limprichtii and A. leansanicus indicate the two should be attributed to the same section, supporting a transition of A.limprichtii from Sect.Crasinna(Stev.)Bunge into Sect.Crasinna(Stev.)Bunge. However, the glabrous upper leaf epidermis and obviously shorter pods in A. leansanicus, as well as the differences of hair arm ratio and stomatal distribution pattern between the two species, combined with their adjacent but not overlapped distribution areas, also support that they are independent and good species.3. Micromorphology of 32 species showed that the main stomatal type of Astragalus is anomocytic, and species in Subgen. Pogonophace Bunge are usually amphistomatic, while some species of Subgen. Phaca (Linn.) Bunge are hypostomatic, especially those species in Sect. Canantrum Koch. For this reason, A. floridus should be taken away from this section.The two related species, A. wenxianensis and A. sutchuenensis in Sect. Lotidium Bunge should be treated as independent species because the former has almost no stomata on abaxial surface while the latter has a considerable number of stomata on its abaxial surface. In addition, A. capillipes, a species in Sect. Melilotopsis Gontsch., being of a considerable number of stomata near the midrib of abaxial surface and the stomata being larger in size, should be re-considered of its systematic position.4. The leaf epidermal features under SEM are of some taxonomic significance with its hair morphology, cuticle ornamentation and wax structure. The hairy surface is usually covered with papillae, and sometimes with striation ornamentation. Stomatal rims are often prominent, smooth or sinuous, sometimes with wax granules. These can be used as systematic study of this genus.5. According to the geographical distribution of those species of Astragalus in Qinling Range, six geographical elements can be concluded, namely, the Chinese - Himalayan element, the Palaeo-Mediterranean element, the Tangutica element, the Northeast Asia to North China element, the Eurasian Steppe to North China element and the Qinling Endemic element. The flora of Astragalus in Qinling Range is most likely immigrated from other aeras, for there are few endemic species in this area and the affinities of those endemic species are mainly distributed out of this aera. This also supports the viewpoint that Qinling Range is a transitional area for the flora between Northern and Southern China.