In this article we will discuss about the size of pollen and spore walls. Size: There exist much variations in sizes of pollen and spores. The size may be 5 µ × 2.4 µ as observed in pollen of forget-me-not (Myosotis) or as high as 200 µ or more as is noted in certain genera of Cucurbitaceae and Nyctaginaceae etc. [...]
In this article we will discuss about the chemical composition and functions of plasma membrane. Chemical Composition of Plasma Membrane: The membrane is mainly composed of lipids, proteins and carbohydrates. Water makes about 29% of total weight. Robertson (1959) proposed that plasma membrane is three-layered structure where proteins form the outer and inner layers of membrane that encloses lipids to [...]
Sporoderm defines the shape of a pollen grain and spore. Erdtman (1952) distinguishes nine common types of shape (Fig. 4.33). The shape classes are based on the ratio between the length of polar axis (P) and equatorial diameter (E). P and E are measured from the equatorial view of a pollen grain and spore. Measurements are taken from the optical [...]