Question

How is it possible in Oxalis and Viola plants, to produce assured seed sets even in the absence of pollinators ?

Hint:

Oxalis and Viola bear cleistogamous flowers that stay closed and self-pollinate, so seeds form without pollinators.

Answer 1

Step 1: Name the type of flowers:
Oxalis and Viola produce two kinds of flowers. One kind is chasmogamous, with open flowers that show exposed anthers and stigma.
The other kind is cleistogamous. These flowers never open.

Step 2: Explain self-pollination:
In a cleistogamous flower the anthers and stigma lie close to each other inside the closed flower.
When the anthers dehisce, the pollen grains touch the stigma and pollinate the same flower.

Step 3: Link to seed set:
No pollinating agent is needed here. So the cleistogamous flowers set seeds assuredly, even when pollinators are absent.

Final Answer:
Cleistogamous flowers self-pollinate without opening, so they assure seed set in the absence of pollinators.