Comparative Study On Embryology In Two Species Of Ribes L.

Ribes (Ribes L.) plant belonging to the Grossulariaceae, under the plant wide distribution and high economic value, have important applications in landscaping, medicinal and edible etc. In recent years in plant morphology, molecular biology, inflorescence and flower structure, plant anatomy, embryology and pollen morphology have some achievements, but for embryology exploration still did not corresponding results published. Normal paraffin sectioning method is used to observe and study the megasporogenesis and microsprrogenesis,the development of male and female gametophytes and flower bud differentiation during development process of Ribes L. The results show that:(1) The anther structure and the development of the anther of Ribes mandshricum (Maxim.) Kom. and Ribes diacanthum Pall. are the same, The flower of them has five stamens, in each of which there are four locules. During meiosis of the mother cell, the division of the cytoplasm can be attributed to the simultaneous type. The tetrad of microspores resulted from the meiosis are simultaneously bilateral and tetrahedral. The mature pollen grains are two-celled.(2) The development of the anther wall of Ribes mandshricum (Maxim.) Kom. belongs to an elementary type. The anther wall can be divided into five layers from outside to inside, they are epidermis, endothecium, two middle layers and tapetum. The development of the anther wall of Ribes diacanthum Pall, belongs to a dicotyledonous type. The anther wall can be divided into four layers from outside to inside, they are epidermis, endothecium, middle layers and tapetum. Tapetum belongs to glandular type. The anther wall of mature pollen only thickened fibrous layer and epidermis.(3) The embryo sac development of Ribes mandshricum (Maxim.) Kom. and Ribes diacanthum Pall. are also the same. The development of embryo sac belongs to the type of polygonum. Their have one ovary, the ovules in which are anatropous, numerous, crassinucellate, placentation parietal and with double integuments. The megasporocyte divides into four linear megaspore in the form of meiosis. The megaspore in chalazal end has a functional ability.(4) Meiotic process is not synchronized. There are some abnormal phenomena in the development of the anther that bring about the pollen degeneration.(5) Ribes mandshricum (Maxim.) Kom. flower bud differentiation is divided into six periods, undifferentiated phase, inflorescence primordium differentiation phase, sepal primordium differentiation stage, stamen, pistil differentiation phase, petal primordium differentiation stage.