Cytogeography of Taraxacum albidum (Asteraceae) in Japan

Chromosome numbers of Taraxacum albidum were examined in 1308 plants collected from 202 localities throughout the distribution areas of this species in Japan. The species had 2n=32 (tetraploid), 39 (hypopentaploid) and 40 chromosomes (pentaploid). Out of 1308 plants examined 88 (6.7%) were tetraploids, 1219 (93.2%) were pentaploids and a plant was a hypopentaploid. Tetraploids were distributed exclusively in Kyushu, whereas pentaploids throughout all the distribution areas in Honshu, Shikoku and Kyushu. Pentaploids had 2 forms of karyotypes, whereas tetraploids showed a uniform karyotype. Thus, 2 forms of pentaploids in karyotype are considered to be distinct clones.