Studies On The Reproductive Biology Of Arnebia Euchroma

With the aid of field observation,paraffin techniques,scanning electron microscope(SEM),the reproductive biology of Arnebia euchroma including the biological characters, vegetative propagation, sexual reproduction, megasporo- genesis, micro sporogenesis and the development of gametophytes,pollination biology has been studied and the reasons which result in its vulnerable status is discussed in this paper.The main results are as follows: I. The habitats of A.euchroma are the enviroment where there is enough moisture, sunlight and fertile soil. The plant shows a kind of aggregated distribution pattern.In this population,the quantity of the long-styled flower plants is similar to that of the short-styled ones.They distribute randomly. 2. This species processes both sexual reproduction by seeds and vegetative propagation by root crown,population regeneration is good. 3. It is self-incompatible and cross-pollination. The breeding system is of self-incompatibility.Natural fruit-set ratio is about 14%. 4.During the sexual reproduction ,the development of the anther wall follows the dicotyledon type.Tapetum is the secretory type.The cytokinesis of the microspore mother cell is of the simultaneous type.The microspore tetrads are trahedral.The mature pollen grain is the three-celled type.The ovary is epigynous,bicarpellary and tetralocules.Each locule contains a single ovule. The placenta is basal placenta.The mature ovules are amphitropous, untegmic, tenuinucellate and have hypostase.The magspore tetrads are linear. Usually, the chalazal megaspore is functional.The development of the female gameto-phyte is of the polygonum type. 5. The pollination of A.euchroma is of entomophily.Some species of insects are engaged in pollianation,of which the main one is Anthophora p/a- giata huger The peak of the visitation of the main pollinators is from 12:30 to 16:30 in sunny day. 6.Artificial factors are the essential reasons which result in this species? vulnerable status.