Taxonomic and phytogeographical problems in Astragalus of the Old World and South-West Asia

Abstract

SynopsisAstragalus, excluding Astracantha (formerly Astragalus subgenus Tragacantha), has a world total of c. 2500 species, of which c. 500 are in the New World; it is one of the largest genera of flowering plants. The estimated number of species in the Flora Iranica area is c. 900–1000. Because of the huge size of the genus, no one person is familiar with all its groups; although 150 sections have been described, many are poorly delimited, often not typified and many untenable. In the Old World the genus is almost entirely restricted to the northern hemisphere. Sections with primitive characters mostly contain mesophytic species widespread in mountains and relatively humid regions; in the more advanced sections the species are adapted to dry or arid conditions.Only a few sections are strictly endemic to the Flora Iranica area (e.g. sects. Microphysa, Acanthophace, Leucocercis). In 2 of the better known large sections (Astragalus and Caprini) there are 2 main centres of diversity: the Armenian knot and the Zagros mountains; Afghanistan and the adjacent Pamir-Alai region. Their patterns of distribution and migration are probably repeated in several other sections in the genus.

Relationships of <i>Astragalus</i> L. in section Sesamei based on morphological criteria and molecular markers

“…minutus. The distance levels among these varieties confirm the observations by Boissier (1872) and Podlech (1986) that A. tribuloides is a multiform species. In the present investigation A. tribuloides var.…”

Cytological study of Tibetia (Fabaceae) in the Hengduan Mountains region, China

“…Among other relatives, Caragana has a similar karyotype, containing only chromosomes with centromeres at median and submedian positions based on x ϭ 8 (Löve 1978(Löve , 1979Gu et al 1993), as does Oxytropis (Gurzenkov and Pavlova 1985;Wang et al 1994). Additionally, some 95% of the species of Astragalus, the most speciose relative of Tibetia, surveyed from Eurasia have the same chromosome number based on x ϭ 8 (Goldblatt 1981;Liu 1984;Ma et al 1984;Gurzenkov and Pavlova 1985;Podlech 1986;Gohil 1988, 1989;Chen and Zhu 1990;Wang et al 1994). Despite some species of Astragalus having a karyotype simliar that of Tibetia and its relatives, there are many species of Astragalus with chromosomes having centromeres at a subterminal position (Wang et al 1994).…”

Variation of Phenolic Compounds Contents in Cultivated Astragalus membranaceus

“…Astragalus is considered to be one of the largest genera, containing about 2,500-3,000 species (annual, perennials, and shrubs) distributed throughout the northern temperate zones (Podlech, 1986). The greatest number of Astragalus species is found in the arid, continental regions of western North America (400 species) and central Asia (2,000 -2,500 species).…”