著者

小山 博滋

出版者

国立科学博物館

雑誌

国立科学博物館専報 (ISSN:00824755)

巻号頁・発行日

vol.1, pp.71-76, 1968

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Cacalia yatabei is a composite plant well known as a member of the Japanese flora. Although the occurrence of this species in the Rikuchu province was reported by TOBA in 1902,no specimen collected in the province was preserved in any main herbaria in Japan. On the course of my field trip, the considerable growth of this species was observed on Mt. Goyo as well as at the Osaki Peninsula. Having these new materials at hands, the phytogeography of C. yatabei is summarized in this paper and the taxonomica1 relationship between the species and its allied is also discussed. Cacalia yatabei MATSUM. et KOIDZ. in Bot. Mag. Tokyo 24 : 152 (1910) Type : HONSHU, Pref. Tochigi : Utanohama, Nikko, J. Matsumura s.n. (TI); KITAM. in Acta Phytotax. Geobot. 7 : 250 (1938), Comp. Jap. III : 223 (1942); HARA Enum. Sperm. Jap. II : 152 (1952); OHWI FI. Jap. Eng. ed. 885 (1965). In C. yatabei, NAKAI recognized two types concerning the number of florets and involucral scales per head; one with 5 florets and 5-(6) involucral scales per head and another with 3 florets and 3-(4) involucral scales per head. Considering these types and some other characters, NAKAI subdivided C. yatabei into two micro-species. The differences pointed out by NAKAI, however, seem to have no taxo-nomic significance at the species level. In addition, there are some intermediate forms between the two types. These two types, therefore, are better considered as infraspecific variations as treated by KITAMURA. Var. yatabei Miricacalia yatabei (MATSUM. et KOIDZ.) NAKAI in Jour. Jap. Bot. 14 : 641(1938) Five florets and 5-(6) involucral scales per head. Var. occidentalis F. MAEKAWA ex KITAM. in Acta Phytotax. Geobot. 7 : 250(1938), Comp. Jap. III : 224 (1942); HARA Enum. Sperm. Jap. II : 152 (1952); OHWI Fl. Jap. Eng. ed 885 (1965) -Miricacalia maekawae NAKAI 1.c. 642 Type : HONSHU, Pref. Nara : Mt. Ohdaigaharayama, S. Sakaguchi s. n. (TI). Three florets and 3-(4) involucral scales per head. As shown in Fig. 1,this species occurs mainly along the Pacific coast of Japan. The northern limit of the distribution coincides well with the border of the deepest (more than 50cm) snowfall region. The dispersal of the plant seems to be related, at least partly, to thawing. Similar distribution pattern is known in some other Japanese plants (e.g., Veronica Miqueliana, etc.). In his revision of the Japanese composite plants, KITAMURA proposed Sect. Taimingasa including the following species : C. amagiensis, C. peltifolia, C. yatabei, C. firma and C. pseudotaimingasa. Among these species, C. peltifolia is fairly unique by its peculiar peltate leaves and its cellular construction of leaf hairs (Fig. 3-F). Cacalia amagiensis, C. firma and C. pseudotaimingasa are taxonomically related to C. yatabei. These four species have leaves with triple-ribbed venation, but the leaf margin is considerably different in serration one another. In C. firma the leaves are slightly lobed, while in C. yatabei they are deeply lobed. The leaves of C. pseudotaimingasa are intermediate between the two. Leaves of C. amagiensis are almost entire, but are more or less lobed in some specimens. Geographically, both C. firma and C. pseudo-taimingasa occur in Korea (Fig. 2); C. amagiensis is found only from Izu Peninsula; C. yatabei is widely distributed in Japan but limited south of the Kitakami Mountains. Considering this distribution, it can be assumed that the ancestor of C. yatabei may had come from Korea Peninsula across Tsushima Strait and spreads northeastwards along the Pacific side of the Japanese Islands up to the Kitakami Mountains.