Chromosome Number and Development of Gametophytes in Euptelea pleiospermum (Eupteleaceae)

Abstract

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.

Key words: Euptelea pleiospermum, chromosome number, microsporogenesis, megasporogenesis, Polygonum type

Pan Kai-Yu, Lu An-Ming, Wen Jie. Chromosome Number and Development of Gametophytes in Euptelea pleiospermum (Eupteleaceae)[J]. .

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Chromosome Number and Development of Gametophytes in Euptelea pleiospermum (Eupteleaceae)

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