Parenchyma (Figs. 8.1, 8.6) is a cell and tissue type in which the cells have only thin primary walls; the cells are unspecialized, lack the characteristic wall of collenchyma and the secondary walls of sclerenchyma; the cells have live nucleate protoplast concerned with various physiological activities in plants; the cells are meristematic, or permanent, simple homogeneous (i.e. composed of one [...]
Phloem consists of sieve cell, sieve tube, companion cell, phloem parenchyma and fibre. 1. Sieve Cell-Origin: The mother cells of sieve cells vary in shape. They are slender, short cylindrical to elongate with both ends tapering. Numerous primary pit fields occur on lateral walls. During differentiation the mother cells elongate. Vacuole appears in the cytoplasm that streams actively. The cell [...]
In this article we will discuss about:- 1. Origin and Development of Vessel 2. Phylogeny of Vessel. Origin and Development of Vessel: Trachea (or vessel) originates from meristematic cells (Fig. 10.4) that are grouped together in a longitudinal file. The meristematic cells are known as xylem mother cell that develops from procambial cells in the primary xylem. In secondary xylem [...]