作 者 ：Pan Kai-Yu, Lu An-Ming, Wen Jie
期 刊 ：植物分类学报 1991年 5期
Keywords:
Abstract:
Euptelea Sieb. et Zucc. is a genus of 2 species, endemic to East Asia and
disjunctly distributed in China and Japan. The present paper deals with cytology and
embryology of the Chinese species E.pleiospermum Hook. f. et Thoms., providing materi-
als for discussing the classificatory rank and relationships of the genus. This work reports the
chromosome number, n = 14 and 2n = 28 (Plate 1: 1, 2), for E.pleiospermum, which is consis-
tent with that of the Japanese species, E. plyandra Sieb. et Zucc.,reported by Sugiure (1931)
and Whitaker (1933).
This number is different from those of the related genera, i. e. n=20 or 2n=40 in
Trochodendron and 2n = 48(46)in Tetracentron (Cronquist, 1981), and, therefore, the cytologi-
cal evidence supports the treatmemt of the genus as a separate family by Smith (1945, 1946),
Chrlotte and Bailey (1946), Cronquist(1981), Thorne (1983), Dahlgren(1983), Wang (1984).
The ovule of E. pleiospermum is anatropous, bitegminous and crassinucellate (Plate 1:
10), the characters which have been already reported by Davis (1966). In addition, the present
work shows that in E. pleiospermum the tapetum is glandular, consisting of 2-or 4-nucleate
tapetal cells; cytokinesus at meiosis of pollen mother cells is simultaneous; microspore tetrads
are mainly tetrahedral; pollen grains are 2-celled (Plate 1: 4, 5, 6, 9), the third megaspore
from the micropyle is functional and develops into the Polygonum type of embryo sac, and
synergids are of a wide-openly dichotomous filiform apparatus (Plate 2: 14, 18;Fig. 1:4,6).
These are the characters reported here for the first time. Due to the lack of embryological da-
ta for the related families, it is impossible to make a systematic comparison of embryology.