Question

Angiosperm flowers may be monoecious, cleistogamous or may show self-incompatibility. Describe the characteristic features of each one of them and state which one of these flowers promotes inbreeding and outbreeding respectively.

Answer 1

Angiospermic flowers exhibit various types of contrivances for pollination. Both self and cross pollination are preferred modes of pollination.

1. Monoecious: Flowers are unisexual that is, contain androecium or gynoecium but are borne on the same plant.

Example, members of Cucurbitaceae family

2. Cleistogamous: Flowers are bisexual, prevent cross pollination by remaining closed. These flowers may be borne underground as in Commelina benghalensis

3. Self-incompatibility: Occurs in bisexual flowers, wherein when the pollen grain is deposited on the stigma of a flower having the same genotype. The process of seed formation is prevented at various stages like, the germination of the pollen grain, movement of pollen tube through the style, fusion of gametes etc

Example, certain species of Brassica, Asclepias, Spathodia etc