In this article we will discuss about:- 1. Distribution of Sporopollenin 2. Chemistry of Sporopollenin 3. Production and Deposition 4. Functions. Distribution of Sporopollenin: It was first observed and named as "sporonin" by John (1814) and latter characterized by Berzelius (1830). Fossil green algae dating back to Devonian period have been shown to contain sporopollenin. The oldest sporopolleninous acritarchs occur [...]
In this article we will discuss about:- 1. Meaning of Pollen Viability 2. Variations in the Viability of Pollen 3. Causes for the Loss 4. Factors. Meaning of Pollen Viability: Pollen viability refers to the ability of the pollen to perform its function of delivering male gametes to the embryo sac. This functional property of the pollen after their release [...]
Pollen wall development may be considered under exine and intine growth phases. 1. Exine Growth Phase: After meiosis of microsporocyte (microspore mother cells) the tetrads of haploid microspores are enveloped by a callosic wall. The callose wall can be detected around the microspore mother cells during initiation of meiosis (Fig. 2.1a and 2.2a). It forms a layer between the cytoplasm [...]