Before illustrating the ontogeny of stomatal complex it may be useful to have a precise definition of the following terms which are used in this essay. The definitions are in accordance with Pant (1965). i. Stoma: It includes the pore and two guard cells. ii. Stomatal complex/stomatal apparatus: It includes a stoma and the adjoining subsidiary cells. It also includes [...]
Sclereids are either oval, rounded or elongated cells with thick Iignified walls that occur singly or in groups in plants. Distribution of Sclereids Cells: Sclereids occur singly or in groups and in association with xylem and phloem in all plant organs. They occur in the aerial roots of Monstera and in the roots of Nymphaea. The stems and petioles of [...]
Collenchyma is a cell and tissue type in which the primary walls are unevenly thickened and consist of homogeneous, more or less elongated living cells; it provides mechanical support to the plant organs where present. i. Distribution: Collenchyma cells are present at the periphery of herbaceous stems, petioles (e.g. Begonia) and in the ribs of some leaves (e.g. Nerium). They [...]