Polarity is defined as the condition of having distinct poles in a pollen grain. Jackson in 1928 assumed that a pollen grain points to the poles like Silphium. Silphium laciniatum, also known as compass plant, has leaves that 'turn their edges north and south and avoid the mid-day radiation' —Willis. Pollen mother cell after meiosis forms four pollen grains that [...]
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 [...]
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 [...]