2003 Volume 54 Issue 1 Pages 1-17
The taxonomy of members in the Arisaema undulatifolium group is revised based on the comparison of eleven morphological traits of 1303 plants from 33 populations. Based on the mean values of six morphological traits for each population, six groups were recognized by cluster analysis. Significant differences among these six groups were found in number of leaflets, width of leaflet, width/length ratio of leaflet, length ratio of peduncle/petiole, auricle size, purple pigmentation and number of ovules per ovary. Five groups recognized by cluster analysis correspond to the existing species, A. aequinoctiale, A. limbatum, A. minus, A. nambae and A. undulatifolium. The sixth group is newly described as A. undulatifolium Nakai subsp. uwajimense T. Kobayashi et J. Murata, which is distinguished from subsp. undulatifolium by the higher width/length ratio of leaflet, the longer peduncle and the more numerous ovules per ovary. Arisaema limbatum var. stenophyllum and A. undulatifolium var. yosinagae and A. limbatum var. aequinoctiale in the sense of Serizawa in J. Jap. Bot. 55, 148-156 (1980) could not be distinguished from each other by any morphological traits examined, and they are thus regarded as a single entity, A. aequinoctiale. Arisaema limbatum var. conspicuum and A. limbatum var. limbatum could not be distinguished from each other.