NPC is an artificial system of classification of pollen and spore based on the three features of aperture only, i.e. number, position and character. Erdtman and Straka (1961) proposed NPC classification and palynologists all over the world accepted it. According to NPC system each pollen grain has an arithmetic cardinal number consisting of three digits. The first digit reveals the [...]
Growth of cell wall involves the growth in surface area as well as growth in thickness. Normally, the entire cell wall grows. Localized growth occurs in fibres, root hairs, tracheids and pollen tubes. A new primary wall grows in surface area. The wall expands due to the turgor pressure exerted on the walls by the protoplast. Turgor pressure is developed [...]
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 & [...]