Stigma
/ˈstɪɡmə/
Definition
Stigma is the pollen-receptive tip or surface of a flower’s pistil, the female reproductive structure. It is usually sticky, feathery, or otherwise adapted to catch and hold pollen. After compatible pollen lands on it, the pollen grain can germinate and grow a tube down through the style to the ovary, where fertilization occurs. This distinguishes the stigma from the style, which supports it, and the ovary, which contains the ovules.
Function in Plants
- Pollen capture: It is the point where compatible pollen lands and is held, often by a sticky or textured surface that improves contact with pollen grains.
- Start of fertilization: After compatible pollen arrives, it supports pollen germination and the growth of a pollen tube down into the flower, linking pollination to seed production.
- Compatibility screening: In many species, it helps control which pollen can succeed. This can reduce self-fertilization and promote genetic diversity through cross-pollination.
- Useful identification feature: Its shape, size, and position can help botanists describe flowers and distinguish plant groups, especially when comparing reproductive structures.
Related Terms
Pistil
Pistil refers to the female reproductive structure of a flower. It consists of one carpel or several fused carpels and…
Style
Style refers to the slender stalk-like part of a flower’s pistil, the female reproductive structure, that connects the…
Ovary
Ovary refers to the enlarged basal part of a flower’s pistil, or female reproductive structure, that contains one or…
Gynoecium
Gynoecium is the female reproductive structure of a flower. It consists of one or more carpels, which may be separate…
Pollination
Pollination is the transfer of pollen from the male part of a flower, the anther, to the female part, the stigma, of…
Pollen
Pollen is a fine, powdery substance made in the anthers of seed plants. It consists of tiny grains that carry the male…