Summary
Highlights
This module introduces sexual reproduction in flowering plants, highlighting flowers as the reproductive parts of a plant. Flowers are not just for beauty but play a crucial role in plant reproduction.
The stamen is the male reproductive part, and the carpel (also referred to as pistil or gynoecium) is the female reproductive part. Flowers can be bisexual (containing both, e.g., pea, China rose) or unisexual (containing either, e.g., corn, cucumber).
A stamen consists of an anther, which produces pollen grains containing male gametes, and a filament. A carpel has three parts: the stigma (terminal part), the style (elongated middle part), and the ovary (swollen bottom part) which contains ovules with female gametes (egg cells).
For sexual reproduction, male gametes must reach female gametes. This begins with pollination, the transfer of pollen grains from the stamen to the stigma. Self-pollination occurs when pollen lands on the stigma of the same flower, while cross-pollination involves transfer to another flower of the same or another plant of the same type. Pollination agents include wind, water, and animals.
Once a pollen grain reaches a suitable stigma, a pollen tube grows through the style to the ovary, delivering male gametes to the ovule. The fusion of male and female gametes forms a zygote, a process called fertilization. The zygote develops into an embryo within the ovule, which then forms a seed with a tough coat. The ovary ripens into a fruit around the seed, and other flower parts fall off. The seed contains an embryo (baby plant) which can grow into a new plant under appropriate conditions.