東南アジアのスミレ属Serpentes亜節について

抄録

Southeast Asian violet group Subsect, Serpentes has about ten species and well characterized by their acaulis stoloniferous habit. It is possible, however, to subdivide them into two distinct groups by some characteristics particularly by those related to seed dispersal. Viola pilosa and its close relative, V. canescens, have such features as possessing decumbent fruiting peduncles, capsules without mechanisms for explosive seed dispersal, large seeds with large elaiosomes (Fig. 2) and styles slightly thickened and downward curved at the apex. The other species are characterized by such features as having erect fruiting peduncles, capsules with explosive mechanism, smaller seeds with smaller elaiosomes (Fig. 2) and styles laterally thickened at the apex. Among these, characteristics related to seed dispersal of the former group are those of purely myrmecochorous species in Viola, V. odorata group, i.e. Subsect. Uncinatae. The shape of style is also somewhat reminiscent in both groups, although the apex does not curve downward so strongly in V. pilosa group as in Subsect. Uncinatae. In some other features such as general habit, chromosome number, both groups seem to share principally the same characteristics. It is doubtless that V. pilosa group and Subsect. Uncinatae are closely related taxa. BECKER's subdivision of Sect. Nomimium should be revised with due regard to these facts. In recent expeditions, specimens of Subsect. Serpentes in Thailand are accumulated in herbarium of Kyoto University (KYO). Their distribution map is shown in Fig. 1. Among them Viola sp. is a taxon common in mountains of Northern and Western part of Thailand and characterized by following features; being almost glabrous, leaves rather coriaceous, with scattered hairs above, elliptic to lanceolate-ovate, up to twice as long as broad, flowers without beards on lateral petals. This taxa exhibits intermediate form between V. glaucescens and V. sumatrana, and seems to be independent species. Specimens of Subsect. Serpentes in Thailand and Malesia deposited in KYO are listed below.