Question

Select true statements.
(a) Lenticels are absent in woody climbers.
(b) Lenticels occur in most woody trees.
(c) The spring wood is lighter in colour and has a lower density.
(d) The sap wood also called as duramen.

• A. Only (a), (b) and (c) are correct.
• B. Both of (a) and (b) are correct.
• C. Both of (b) and (d) are correct.
• D. Both of (a) and (c) are correct.

Answer 1

The correct option is A Only (a), (b) and (c) are correct.

Cambial activity produces secondary tissues that push and rupture epidermal cell and outer cortex, a new protective layer, periderm is formed. Periderm divides to form cork cambium or phellogen which in turn produce cork or phellem towards the periphery and phelloderm on inside. These secondary tissues cause pressure and rupture epidermis at several places to form openings called as lenticels. Thus, they are result of secondary growth which is characteristic feature of woody plants.

The cambial activity occurs only twice during every year, once in the spring and once in the autumn. The secondary xylem that is formed in the spring season is known as springwood or early wood, cambium is more active in spring and forms more number of vessels with wider cavities thus, the ring has lower density, absence of tennin or resin and other chemicals that make the heartwood dark in colour, make it light in colour. Heartwood, also termed as duramen, is the central region of old trees, that is formed earlier during growth. It has tannins, resin and other substances imparting it the black colour and serves to provide mechanical support. Sap wood in outer region of recently formed wood which is lighter in colour.
Thus, the correct answer is option A.