Flowering plant reproductive organs.
Angiosperms, or flowering plants, are vascular, bisexual plants. Both the male and female reproductive organs are found in a single flower. While these plants can self-fertilize, cross-fertilization (pollen from a different plant) is important to maintain genetic diversity. The carpel is a specialized organ, unique to angiosperms, that encloses the ovule and eventually matures into fruit following fertilization (Figure 3). Angiosperms are called covered seed plants because the developed seed (zygote/embryo) is within the fruit.
Angiosperms have distinct reproductive organs called flowers. The gametophyte is reduced to the female embryo sac, which has as few as eight cells. Pollen grains, the male gametophyte, developed to protect the sperm during the transfer from male to female parts. Double-fertilization is also unique to these plants. Like the gymnosperms, a pollen grain that reaches the carpel will germinate. Pollen tubes grow towards the ovary and two sperm are released. One sperm nuclei fuses with the egg to form the zygote (2n). The other nuclei unites with two haploid polar cells (in the ovary) to form a triploid (3n) cell that develops into the endosperm, a nutrient-rich tissue surrounding the seed (fruit).
- What are some unique characteristics of angiosperms