东北地区野豌豆属VICIAL．物种生物学研究Ⅷ．幼苗形体结构动态和种间界限

Biosystematical Studies on Northeast China Vicia L. Ⅷ. Structure Dynamic off seedling Forms and Demarcation of Species

在野外居群调查的启示下，本文以组件观点对柳叶野豌豆复合种和歪头菜幼苗亚单位的时序变化与开花关系进行了分析。结果发现在柳叶野豌豆复合种栽培居群中存在打破物种间形体结构特征的个体，即在复叶由一对小叶组成的植株就已开花而进入生殖时期。另外，在歪头菜的野生居群中发现由三或四枚小叶组成复叶的个体，因此，我们推测这种形体结构的变化可能暗示着柳叶野豌豆复合种和歪头菜有着共同的祖先。

The micropyle of Brassica napus includes anexostome and an endostome. The exostome is basically open, but the endostome is a closed structure with only narrow gaps between two cuticle layers of the inner integumental epidermis. The embryo sac is composed of two synergids, an egg cell and a central cell; the antipodal cells are degenerated before the embryo sac maturation. The synergid has a micropylar filiform apparatus, but not a chalazal vacuole, and its nucleus is centrally located. Therefore it has not a typical polarity as synergids of most other plant species. Before pollination, the synergids of some ovules already show symptom of degeneration. After pollination but before entry of pollen tube, two synergids of the same embryo sac degenerate simultaneously. The egg cell is a typical polarized cell, with a big micropylar vacuole and a chalazally located nucleus. Before fertilization, the arch-shaped gap between two plasma membranes of the egg cell and central cell is filled with electro-densed granular and amorphous substances. The central cell possessed several big chalazal vacuoles; the polar nuclei and most cytoplasm are micropylarly located. The plastids in the central cell is characterized by big volume and quite prominent lamellae. The micropylar portion of the embryo sac wall bear well-developed ingrowths, which gradually sooth down towards the chalazal end.