Chromosome Numbers of North American species of Antenaria gaertner (Asteraceae: Inuleae)

Bayer, R.; Stebbins, G.

Chromosome numbers are presented for 99 populations of 13 species of Antennaria, including A. plantaginifolia, A. neglecta. A. virginica, A. solitaria, A. racemosa, A. corymbosa, A. rosea, A. media, A. Parlinii, A. fallax, A. neodioica, A. canadensis, and A. petaloidea. Four species from the eastern United States (A. plantaginifolia, A. neglecta, A. solitaria, and A. virginica) were determined as diploid (n=14), and thee are all sexual. Diploid counts were also obtained for two sexual species (A. racemosa and A corymbose) from the western United States. Chromosome counts are presented for two heteroploid agamic complexes occurring in the eastern United States; these include what have traditionally been referred to as A. Parlinii, A. fallax, A. neodioica, A. canadensis, and A. petaloidea. Determinations of 2n=56,70,84, and 112 were obtained for the A. Parlinii and A.fallax groups, where 2n=84 had been the only number previously reported. Numbers of 2n=84 were confirmed for A. petaloidea and A. canadesis and 2n=56 for A. neodioica. The western United States polyploid species (A. rosea and A. media) are reported as 2n=56. The presence of apomixis is correlated with polyploidy. The distribution of chromosome numbers in eastern United State Antennaria demonstrates that two diploids and many polyploids occur above the glacial margin, and thus there is an increase in the frequency of polyploids with latitude. Colonization of the glaciated region by Antennaria following the recession of the Wisconsin ice sheet is also duscussed. Many of the polyploids occur only in the glaciated region, thus suyggesting a recent origin for these cytotypes. There is evidence indicating that the orginal base number in Antennaria may be x=7.

Chromosome Numbers of North American species of Antenaria gaertner (Asteraceae: Inuleae)

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