EVOLUTION AND VARIATION IN TRILLIUM. VII. MIGRATIONS BETWEEN NORTHERN AND EASTERN POPULATION GROUPS OF T. KAMTSCHATICUM

In the foregoing paper of this series (Fukuda et al., 1960), migrations among natural populations of Trillium kamtschaticum across the Ishikari Depression, a narrow depressed area connecting the southern part of Hokkaido with the central part, were investigated. The present paper deals with migrations that have taken place in the north-eastern region (Kitami Province) of Hokkaido, where the northern population group (North) of this plant borders on the eastern one (East). The front of the contact of these two groups ranges from the seashore of Okhotsk, passing through the interior of Kitami Province, to the central part of Hokkaido, where volcanoes of central Hokkaido divide the two groups (fig. 2 in Fukuda et al., 1960 and fig. I in the present paper). Seven populations, Ke, Op, Sk, Ab-1, Ab-2, Mb and Tp, distribtuted in the coastland facing the sea of Okhotsk and two, B1z and Ot, from the coastland of Nemuro Province, were chosen for examination. Also, four populations Eg, Ok, An and Kt, were taken from the interior of Kitami Province (fig. 1 ). The migrations were examined by making analyses of chromosome composition of these populations.