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A study of the variation in Trifolium burchellianum ssp. johnstonii (Fabaceae)
Author(s) -
Ryding Olof
Publication year - 1991
Publication title -
nordic journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.333
H-Index - 33
eISSN - 1756-1051
pISSN - 0107-055X
DOI - 10.1111/j.1756-1051.1991.tb01410.x
Subject(s) - biology , botany , ploidy , pollen , fabaceae , herbarium , chromosome number , taxon , chromosome , karyotype , gene , biochemistry
A study of the variation within the tropical African taxon Trifolium burchellianum ssp. johnstonii , including var. oblongum , is made on the basis of herbarium material and cultivated material. The chromosome numbers 2n = 48 and 2n = 96 were counted in the collections of var. johnstonii and var. oblongum respectively. In most other material, the chromosome number has been estimated from the size of the pollen grains and guard cells. Var. johnstonii was found to have both 2n = 48 and 2n = 96 and var. oblongum was found only to have 2n = 96. Var. oblongum and var. johnstonii with 2n = 96 are found to have complementary distributions, while the distribution of var. johnstonii with 2n = 48 is found sympatric with all the 2n = 96 material. The sterility barriers are persumed to have become weakened at the higher ploidy level, and gene flow is presumed to explain the continuous variation between the two varieties. The origin of var. oblongum is also discussed.