Cytogenetic study of some Thai species of flowering plants
Puangpaga Soontornchainaksang | Kanyarat Chaiyasut (Mahidol Univ.,Bangkok (Thailand). Faculty of Sciences. Dept. of Plant Sciences)
Chromosome numbers of 39 varieties of 33 Thai species belonging to 9 genera of Amaryllidaceae, Bignoniaceae, Caesalpiniaceae, Fabaceae and Liliaceae were investigated. Somatic numbers and meiotic configuration were determined with Feulgen squash or smear technique. Somatic numbers obtained are between 14 and 56 consisting 19 species of diploid 12 species of tetraploid 1 species of triploid and 1 species of allooctoploid. Moreover B-chromosome was found in Crinum amabile Donn. (2N=33+if) Tabebuia rosea (Bertol.) DC. (2N=20) Cassia angustifolia Vahl. (2N-28) C. bakeriana Craib (2N=28) C. biflora Linn. (2N=28) C. garettiana Craib (2N-28) and C. spectabilis DC. (2N=28). And there are three species which have different chromosome numbers from earlier studies those are Cassia alata Linn. (2N=28) C. surattensis Burm.f. (2N=56) and Chlorophytum elatum R.Br. var. variegatum (2N=28). However most flowering plants studied in the same genera showed the same chromosome number or different in ploidy level except the genus Zephyranthes. And most plants stydied of the same species consisted of the same somatic numbers but there is an important remark for chlorophytum elatum R.Br. var. variegatum and C. elatum R.Br. var. vitatum. Taxonomist determined these two plants in the same species while their chromosomes differ in numbers and types. The first variety has somatic number 2N=16 but it is 2N=28 for the second. These results should be considered to classify Chlorophytum elatum R.Br. var. variegatum and C. elatum R.Br. var. vitatum into two species.
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