In which of the following plant organs is collenchyma tissue absent?

Deciduous plants shed their leaves during hot summer or in autumn. This process of shedding of leaves is called abscission. Apart from physiological changes,what anatomical mechanism is involved in the abscission of leaves?

Thick-walled and lignified with simple pits in walls and non-prosenchymatous cells without living protoplasm, usually isodiametric or irregular in shape, are:

From both phylogenetic and ontogenetic points of view,which tissue is regarded as the most primitive?

In the first formed primary xylem,the secondary wall thickening may be of

Laticiferous cells usually contain