作 者 ：Xu Han-Qing, Huang Qing-Yuan
期 刊 ：植物分类学报 1989年 4期
关键词：秤锤树雌配子体雄配子体；
Keywords:Sinojakia xylocarpa, Male gametophyte, Female gametophyte,
Abstract:
Observed in this paper was the development of the microspore and megaspore,
male and female gametophytes in Sinojakia xylocarpa, which is endemic to China.
The anther comprises four microsporangia. Microspore wall forms simultaneously after
meiotic division in PMCs. The arrangment of microspore in a tetrad is tetrahedral. Bicel-
lular pollen grains appear at the shedding stage. ‘They are 3-colporate, with irregular min-
ute-faveolate exine sculpture. The anther wall development is of the dicotyledonous type, and
its endothecitum develops slight fibrous thickenings, which also form on some epidermal cells.
The tapetum is glandular.
The pistil with hollow style is composed of three carpels, and its ovary contains several
anatropous ovules. The ovule is unitegmic, tenuinucellar, but no obturator was observed. The
archesporial cell functions directly as the megaspore mother cell which forms a linear tetrad,
but T-shaped tetrad was found in a few ovules. A Polygonum type embryo sac forms from
the functional chalazal megaspore. In the mature embryo sac, the synergids are elongate with
a large vacuole at the chalazal end, but the distrihution of vacuoles in the egg cell appears
random.
Two polar nuclei remain in contact with each other for a spell before the fertilization
and the 3 antipodal cells may persist into early postfertilzation stages. Numerous starch gra-
ins occur in the embryo sac.
According to the present embryological studies on Sinojakia xylocarpa and the works on
embryogenesis by some early embryologist, authors consider that Styracaceae, Symplocaceae,
Sapotaceae and Ebenaceae are rather closely related, and we alsoconsider it reasonable to put
the 4 families mentioned above in Ebenales.