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 aperture found in the pollen and spore wall of plants. It is a weak, preformed locus on the exine of spore and pollen through which the intra-exinous substance exits and pollen tube emerges during pollen germination. Apertures may be absent from a pollen grain or spore when they are termed as inaperturate/atreme/non-aperturate [...]