Angiosperms are a group of plants that produce flowers and the flowers can in turn produce seeds that are enclosed within a carpel. The structure found in the male reproductive organ which is responsible for formation and development of the pollen grains is known as microsporangium.Complete answer:
Angiosperms are a group of flowering plants. Angiosperms are able to produce seeds which remain enclosed within the carpel of the flowers. Herbaceous plants, shrubs, grasses, and most trees are included in the groups of angiosperms.
Generally, the flower possesses the reproductive organ in the angiosperms. There are two parts of the reproductive organ found in flowers. One is the female reproductive part and the other is the male reproductive part. The female parts of the reproductive organ are called megaspores, which will divide to form the egg cell and it is enclosed in the carpel. And the male reproductive part is known as stamens. In the male reproductive cells, microspores are present which produces the pollen grains.
The male reproductive part of angiosperms or stamens is consisting of two parts, one is filaments and the other part is anthers. Anthers are lobed like shapes that present in the top of filaments. Here the anthers are bilobed. In each lobe of anthers, two thecae are observed, that is there is a total of four thecae present in both lobes. Due to the presence of two thecae in a lobe, then the anthers of angiosperms are called dithecous.
Microsporangia is the structure that is mainly responsible for the production and releases of pollen grains. The thecae acts as the microsporangium. There are four layers found in the microsporangia and the four layers have a different role in the maturation of pollen grain. These four layers are the epidermis, endothecium, middle layers, and tapetum. The epidermis is the outermost layer of microsporangia, after that the endothecium is present. The next layer is the middle layers. And the innermost layer is the tapetum. Generally, the outer three layers are protective in nature and help in the releases of the pollen grains, and the inner layer the tapetum provides the nourishment to the pollen grains and also serves as the precursors for the formation of pollen grains.Note:
All flowering plants belong to the group of angiosperms. The flower is the reproductive organ of the angiosperms which have two parts; male reproductive parts or stamens and female reproductive parts or carpels. The stamens are composed of filaments and anthers. These anthers are bilobed and possess two thecae in each and the anthers are called dithecous. These thecae act as microsporangium which produces the pollen grains. The structure of the microsporangium is composed of four layers. The outermost layer is the epidermis after that endothecium is found, and then the second layer or middle layer is present. And the innermost layer is the tapetum.