In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to :
(a) secretion of secondary metabolities and their deposition in the lumen of vessels.
(b) deposition of organic compounds like tannins and resins in the central layers of stem.
(c) deposition of suberin and aromatic substances in the outer layer of stem.
(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.
(e) presence of parenchyma cells, functionally active xylem elements and essential oils.
Choose the correct answer from the options given below :
what is the role of large bundle sheath cells found around the vascular bundles in C4 plants?
The anatomy of springwood shows some peculiar features. Identify the correct set of statements about springwood.
(a) It is also called as the earlywood
(b) In spring season cambium produces xylem elements with narrow vessels
(c) It is lighter in colour
(d) The springwood along with autumn wood shows alternate concentric rings forming annual rings
(e) It has lower density
Choose the correct answer from the options given below:
| List-I | List-II | ||
|---|---|---|---|
| (a) | Lenticels | (i) | Phellogen |
| (b) | Cork cambium | (ii) | Suberin deposition |
| (c) | Secondary cortex | (iii) | Exchange of gases |
| (d) | Cork | (iv) | Phelloderm |
Choose the correct answer from the options given below.