KARYOMORPHOLOGICAL STUDIES ON WOODWARDIA-SENSU-LATO OF JAPAN

Karyomorphological comparisons were made of five species of Japanese Woodwardia. There were no marked differences at interphase and prophase among the five species. Woodwardia japonica, W. prolifera, and W unigemmata were diploid with 2n = 68 and the formulas of their metaphase karyotypes uniformly 4m(median centromeric chromosomes) + 12sm(submedian) + 52(st + t)(subterminal and terminal). Woodwardia orientalis was tetraploid with 2n = 136 and 8m + 24sm + 104(st + t), and the ratio of each chromosomal type to total complement was identical to that of three diploid species. These four species had several characteristics in common: x = 34, the longest chromosome of sm, and a mean chromosome length over 3.0 mum. Although Woodwardia orientalis showed some similarity to W. prolifera, it seems to be an allotetraploid which originated by chromosome doubling of a hybrid of W prolifera and a diploid species as yet karyomorphologically unknown. Woodwardia kempii was tetraploid with 2n = 124 and 8m + 24sm + 92(st + t), and differed from the others in having x = 31, the longest chromosomes of t, and a mean chromosome length under 3.0 mum. This species has been classified as an independent genus, Chieniopteris, and our karyomorphological study supports this treatment.