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 [...]
In this article we will discuss about the layers of the spore and pollen wall. Sporoderm stratification (Erdtman's concept): Sporoderm (L. sporodermis), i.e. the spore and pollen wall is composed of distinct layers or subdivisions, the sequence of which is as follows from outside inwards in a fresh pollen grain and spore. Sclerine (Gr. Scleros means hard-Fig. 4.1 A & [...]