关键词: 银杏, 叶籽银杏, 叶生小孢子囊, 比较形态学, 系统发育

Abstract: Comparative morphology of ep iphyllous microsporangia Ginkgo, which was discovered by au2
thor for the first time in China, were examined under light microscope (LM) , scanning electron microscope
( SEM) , and its systematic imp lication was discussed. The research results showed that there exists the normal
microsporangia and ep iphyllousmicrosporangia on ep iphyllous microsporangia Ginkgo tree. These leaves with
ep iphyllousmicrosporangia are smaller than that of normal leaves, and with 1 to 3 deep lobes attached by 1 -
9 microsporophyll, sometimes 1 - 3 (5) microsporophyll clustered on the boundary of lamina and petiole, and
the microsporophyll without stalklet. There is no significant difference in anatomical structure between the
leaves with ep iphyllousmicrosporangia and normal leaves, excep t the thickening in the site where ep iphyllous
microsporangia inserted. The transections of both kinds of leaves comp rise ep idermis, mesophyll and veins,
and there is no significant palisade tissue and spongy parenchyma. There is diversity in the number of ep iphyllousmicrosporangia per leaf, inserted site, and morphological features. The normalmicrosporangia is ellip tic,
while the ep iphyllousmicrosporangia is almost circular, and the microsporangia wall consists of 4 - 7 layers of
cell. At the time of pollen shedding, the tapetum was degenerated to vestige in both kinds ofmicrosporangia.
The polar axis and the equatorial axis of pollen p roduced in ep iphyllous microsporangia are 19199 μm and
13160μm, respectively. The number of pollen in ep iphyllousmicrosporangia averages 18 600. Normal pollen is slippery2grained type, but ep iphyllous pollen is rough2grained type. The pollens in ep iphyllousmicrosporan2
gia have capability to germinate. The ontogeny of ep iphyllousmicrosporangia Ginkgo indicated that the micro2
sporophyll in Ginkgo is of phyllome origin. Possibly, the ep iphyllous microsporangia is a peculiar chimera.
Phylogeny on ep iphyllousmicrosporangia Ginkgo was discussed in the article.

Key words: Ginkgo biloba L., Ginkgo biloba L. var. epiphylla Mak., Ep iphyllous microsporangia, Comparative morphology, Phylogeny