碩士 / 國立成功大學 / 生物學研究所 / 85 / Utricularia gibba L. (syn. U. exoleta R. Br.) is a suspended aquatic plant with carnivorous habit. Floral morphogenesis as well as pollen and embryo sac development in ultrastructural and histochemical aspacts are investigated to elucidate its breeding behaviour.
The floral organogeny of U. gibba is generally similar to that of other investigated species in the genus. The development of anther wall is a dicotyledonous type. The callose wall is only present at early microspore tetrad. First vacuolation and intine systhesis occur at the late tetrad. Occasionally pollen grains with an unuaual incompletely seperating wall can be observed since the late bicellular stage. The secretory tapetum is responsible for the secretion of filament material, that causes the release of microspore, the production of the locoular fluid, and the formation of the exine precusors. The ovules are anatropous, unitegmic and tenuinucellate. During ontogeny, the nucellus cells near the micropylar end degenerate and in the same time the embryo sac extends beyond the ovule to contact with the placental nutrient tissue at 2-nucelate embryo sac stage. Hence a true micropyle is absent in U. gibba, whereas a narrow and long passage is still present between the integument and the placenta outside the disappeared micropyle. The embryo sac development is Polygonum-type and typical for the genus except that the egg apparatus is situated at the antiraphe side near the micropylar end. The pathway of pollen tubes during pollination and fertilization is also observed.
The pollen in situ germination, the position of anther facing to the funcitonal stigmatic lobe at dehiscence, and the synchronic maturation of both male and female gemetophytes may be the characteristics which promote the self-pollination. But during the flowering season, the corolla normally falls in two days at anthesis and the stamens may fall with corolla before dehiscence. End of flowering season, in contract, corolla keep attached. Therefore the anthers dehiscence in situ. Consequently, the timing for anther dehiscence together with the falling of corolla could influence the breeding behavior in U. gibba.
| Identifer | oai:union.ndltd.org:TW/085NCKU3112005 |
| Date | January 1997 |
| Creators | 傅秀蘭 |
| Contributors | 郭長生 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 153 |
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