日本産ヒシ科数種の核形態  [in Japanese] Karyomorphology of Some Trapaceae in Japan  [in Japanese]

日本産ヒシ属(ヒシ科)4taxaについて, 若い葉の細胞を利用して調べた核形態を初めて報告する。ヒメビシ(Trapa incisa)及びオニビシ(T.natans var.japonica)は共に2n=48, ヒシ(T.japonica)は2n=96, コオニビシ(T.natans var.pumila)は2n=ca.96の染色体をもつことが明らかになった。間期核はいずれも単純染色中央粒型を示し, 中期染色体長は0.3-1.2μmと小さく, また, 染色体基本数はχ=24(或いはχ=12)であることが分かった。2n=96(或いは2n=ca.96)の染色体数をもつヒシ及びコオニビシは共に, 2n=48のヒメビシ及びオニビシとの雑種起源の複二倍体或いは複四倍体である可能性が示唆された。

Karyomorphology of four taxa of Trapa native to Japan were studied for the first time using meristematic cells of young leaves. Chromosome numbers reported are 2n=48 in T. incisa, 2n=96 in T. japonica, 2n=48 in T. natans var. japonica, and 2n=ca. 96 in T. natans var. pumila. 2n=96 in T. japonica and 2n=ca. 96 in T. natans var. pumila are numbers unknown elsewhere in the genus so far. Features common to all the taxa investigated are : (1) interphase nucleus has the simple chromocenter type ; (2) chromosomes at metaphase mostly small(0, 3-1.2μm long by our methods) ; (3) χ=24(or 12). Evidence available suggests that 2n=96 in T. japonica and 2n=ca. 96 in T. natans var. pumila are amphiploids hybridized between T. incisa and T. natans var. japonica with 2n=48.