A synopsis of genus Astragalus L. sect. Stereothrix Bunge Fabaceae

Authors : Massoud RANJBAR, Bahareh MAHMOUDIAN, Ernst VITEK

Pages : 114-133

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Publication Date : 2013-04-15

Article Type : Research Paper

Abstract :A synopsis of Astragalus sect. Stereothrix Bunge Fabaceae is presented and the relationships between the species are discussed within the section. A description for the section and a key to its 15 species in Iran are given. Also two ignored species belonging to the section in Flora Iranica, Astragalus badelehensis Maassoumi & Taheri and A. mahneshanensis Maassoumi & Moussavi, are reviewed again here. A. savanatensis and A. andabilensis collected from Fars and Ardebil Provinces of Iran, respectively are described as new species, illustrated are compared with their nearest relatives. A. savanatensis is a rare species in the subalpine areas of Estahban and closely related to A. ledinghamii Barneby occurs in the same area. The habit, shape of calyx and petals are very similar in both species, but A. savanatensis differs sufficiently from its relative by having peachy flower vs. yellowish white , plant length 24.5 -34 cm vs. 7 -- 20 cm , stem length up to 20 cm vs. 1 -- 3 cm , leaflet in 4–6 vs. 2 -- 4 pairs, leaflet size 5 -- 45 × 1 -3 mm vs. 7 -- 25 × 1.3 -- 2 mm , keel length 8 -- 10 mm vs. 6.8 -- 7.6 mm and peduncle length 9.3 -- 18.5 cm vs. 2 -6 cm . A. andabilensis is a rare species occurs in the subalpine areas of Khalkhal and closely related to A. capito Boiss. & Hohen. occurs in Tehran province. The habit, shape of calyx and petals are very similar in both species, but A. andabilensis differs sufficiently from its relative by plant length 11.5 -- 21.5 cm vs. 4 -- 9 cm , white stem hairs toward the nodes increasingly black vs. all white stem hairs , appressed hairs on the upper sides of leaflets vs. spreading hairs , white peduncle hairs toward the raceme increasingly black vs. all white hairs and peduncle length 5 -- 14.5 cm vs. 0.5 -- 2 cm . In addition, meiotic chromosome number and behavior were studied in the new species. This report is the first cytogenetic analysis of these taxa. Both species are diploid plants and possess 2n = 2x = 16 chromosome numbers, consistent with the proposed base number of x = 8. The general meiotic behavior of the species was regular, with bivalent pairing and normal chromosome segregation at meiosis. However, some meiotic abnormalities in A. savanatensis include varied degrees of ring and fragmented chromosomes, precocious migration in metaphase I and II, bridges and laggards in anaphase I and II, micronuclei in telophase I, binucleate in telophase I and II and tripolar cells in telophase II. In A. andabilensis, fragmented chromosomes in metaphase I and II were observed. Asynchronism in meiosis was seen in both species
Keywords : Astagalus savanatensis, A andabilensis, Iran, Meiotic behavior, Astragalus, Sect Stereothrix