Question
Biology Question on Secondary Growth
Bark refers to
A
phellem + phellogen + phelloderm
B
periderm + cortex
C
phellem + phelloderm + secondary phloem
D
periderm + cortex + pericycle + secondary phloem
Answer
periderm + cortex + pericycle + secondary phloem
Explanation
Solution
Bark is a loose term and is used to define all the tissues outside vascular cambium. It is differentiated into outer bark or rhytidome (consisting of dead cells) and inner bark (of living cells, i.e., periderm, cortex, pericycle and secondary phloem). The outer layers of the bark are being constantly peeled off on account of the formation of new secondary vascular tissues in the interior. Bark is insect repellent, decay proof, fire-proof and acts as a heat screen.