日本産テンナンショウ属の分類形質と分類 : (1)アマミテンナンショウ,オオアマミテンナンショウとオキナワテンナンショウ

抄録

The taxonomy of the three infraspecific taxa of A. heterocephalum KOIDZ. (i.e. heterocephalum, okinawaense and majus) was revised based on a comparison of critical characters in material obtained through field studies. Variation ranges of the representative taxonomic characters were examined and compared between those taxa, then they compared with those of A. du-bois-reymondiae, a Chinese species most closely related to A. heterocephalum. The results are as follows : 1. The average number of leaflets of the lowest foliage leaf is smallest in okinawaense and largest in majus (Fig. 3). Using Duncan's multiple range test, it is clear that the variation ranges of the three groups differ significantly. 2. The scatter diagram of the lengths and widths of the terminal leaflet (Fig. 4) shows that the variation ranges of okinawaense and majus overlap widely. The leaflets of heterocephalum are narrower than in the other two, and the variation range of heterocephalum is quite different ; there is no overlap of these characters in female plants. 3. The scatter diagram of the length of the spathe-tube and spathe-blade (Fig. 5) shows that the variation ranges of the three groups are quite different. The spathe-blade is generally shorter in heterocephalum than in the other two taxa, of which majus has a longer spathe-tube and okinawaense has a shorter one. In female plants, the range of variation in okinawaense and majus do not overlap. The variation range of A. du-bois-reymondiae situates at the overlapped portion of the three groups of A. heterocephalum. 4. The scatter diagram of the length and width (diameter) of the spadix-appendage (Fig. 6) shows that this character differs between male and female plants. The spadix-appendage is distinctly longer in female than male but the diameter is not so different. In comparing the male plants of the three groups (Fig. 7), the spadix-appendage is smallest in heterocephalum and largest in majus. The variation range of this character of A. du-bois-reymondiae is mostly within the range of majus and partly overlaps the range of okinawaense. The differences in the characters in the three groups of A. heterocephalum are summarized in Table 1. This data shows that the three groups are clearly differentiated from each other, almost to the extent of the difference that exists between A. du-bois-reymondiae and A. heterocephalum, two taxa have been geographically isolated for a long time and are considered to be distinct species. Consequently, the three groups of A. heterocephalum are recognized in the rank of subspecies. A new combination, Arisaema heterocephalum subsp. majus (Serizawa) J. Murata, is made.