We have investigated the cytological features of Ixeris nakazonei, a species endemic to the Ryukyus, with a putative hybrid origin between L rqpens and L debilis, The chromosome number ef L nakazonei was determined as 2n=32 (tetraploid), 40 (pentaploidand) and 48 (hexaploid), for the first time, Because the chromosome number 2n=32 is numerically interrnediate between that of L repens (2n=16) and L debilis (2n=48) or the hexaploid of L nahazonei, and the tetraploid plants always occur side by

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... e with them, the tetrap)oid of J. nakazonei. 1ikely arose from hybridization between L repens and L debilis or L repens and the hexaploid of L nakaconei, The pentap]oid is a very rare cytotype, and considering its chromosome number, may have originated by hybridization between either the tetraploid and L debitis or the tetraploid and the hexaploid ef L nakaionei, Because the hexaploid of L nakazonei and L debitis haye the sarne chromosome number of 2n=48 and L nakazenei, L repens and L debiJis all have simi]ar symmetric karyotypes and relatively srnall chremosomes, we can not infer the origin of the hexaploid based onty on the cytologjcal features.