Taxonomical Study On Astragalus With Medifixed Hairs In The Northwest Part Of Xinjiang

In this paper we dealt with the taxonomy of the genus Astragalus with medifixed hairs in Mountainous Boundary Area with Kazakhstan, west of Junggar Basin, Xinjiang, China. The main results are as follows:1. According to filed research and herbarium study, we concluded that there are 26 species of the Astragalus group in this area, of which one new record to China, four not included in Flora Reipublicae Popularis Sinicae. Additional distributional data were added to six species in this area.2. The misidentification of A. arcuatus Kar. et Kir. in Flora Reipublicae Popularis Sinicae was reviewed in this paper, and the observation of hair morphology under SEM supported the transformation of A. pavlovii (=A. lioui) from Subgen. Cercidothrix Bunge Sect. Craccina (Stev.) Bunge into Subgen. Phaca (Linn.) Bunge Sect. Hemiphaca Bunge. .3. Anatomical study of 44 species showed that isolateral leaves are predominant in this Astragalus group, with dense hairy on both surfaces. Stomatal types are of anomocytic or anisocytac, of which the former are more common. Leaves with developed vascular systems and sunken stomata, stand for strong xerophytic characters that are adaptative to their drought environment.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.5. The medifixed hairy Astragalus may be originated from basifiexd ones that mainly centered in Tethys area since the end of Tertiary. The modern distribution center of medifixed species is now in Middle Asia, with its most diversity in Iran and Turkey. The distribution of this group in China is the eastward of its modern distributional center, and in the migration process, some new diversification were taken place. Now the group is widely distributed in temperate area of Northwest, Southwest and North China, especially has its diversity in Northwest China.