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 [...]
Plasmodesma (plural: plasmodesmata) is thin irregular cylinder of cytoplasm lined by plasmalemma, passing through fine pores in the cell walls, thus forming a connection between the cytoplasm of adjacent cells. They are found in higher plants and fluctuate widely in abundance and distribution. They are commonly present in primary pit fields and pit membranes of young and mature living cells [...]
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 & [...]