Question

Pioneers of vegetation on rocks are ___________.

• A. Pteridophytes
• B. Bryophytes
• C. Gymnosperms
• D. Lichens

Hint:

Ecological succession on rocks begins with lichens, followed by bryophytes and higher plants.

Answer 1

The Correct Option is D

Step 1: Understanding pioneer species.
Pioneer species are organisms that first colonize barren and harsh environments such as bare rocks. These environments lack soil, nutrients, and moisture, making survival difficult for most plants.
Step 2: Role of lichens.
Lichens are a symbiotic association of algae and fungi. They can grow directly on bare rocks and release organic acids that slowly break down rocks into soil, initiating the process of ecological succession.
Step 3: Analysis of options.
(A) Pteridophytes: Require soil and sufficient moisture, so they cannot grow on bare rocks.
(B) Bryophytes: Need a thin layer of soil, which develops only after lichens colonize the rocks.
(C) Gymnosperms: Advanced plants that require well-developed soil.
(D) Lichens: Correct, as they are capable of surviving on bare rocks and initiate soil formation.
Step 4: Conclusion.
Lichens are the pioneers of vegetation on rocks because they initiate soil formation and ecological succession.