(A) What are Casparian strips and what is their function ?
(B) Define concentric vascular bundle. What are their types ?
(C) What is wood botanically ?

Explanation

(A) The radial and transverse walls of epidermal cells possess a waxy substance called suberin in the form of bands or strips. These strips were first observed by Caspary (1865-66) and hence, called Casparian strips. These strips help endodermis to act as 'water tight' layer out side the vascular strand and stops passive movement of water and minerals. It also prevents the conducting elements being clogged with air.
(B) A vascular bundle in which one kind of vascular tissue is completely surrounded by the other kind of vascular tissue, 'is called concentric bundle. The concentric bundles are of two types - (i) Amphivasal and (ii) Amphicribal
(C) Wood is defined as the main strengthening and water conducting vascular tissue in stems and roots.