Biology » Seed Plants » Angiosperms

Summarizing Angiosperms


Angiosperms are the dominant form of plant life in most terrestrial ecosystems, comprising about 90 percent of all plant species. Most crops and ornamental plants are angiosperms. Their success comes from two innovative structures that protect reproduction from variability in the environment: the flower and the fruit. Flowers were derived from modified leaves. The main parts of a flower are the sepals and petals, which protect the reproductive parts: the stamens and the carpels. The stamens produce the male gametes in pollen grains. The carpels contain the female gametes (the eggs inside the ovules), which are within the ovary of a carpel. The walls of the ovary thicken after fertilization, ripening into fruit that ensures dispersal by wind, water, or animals.

The angiosperm life cycle is dominated by the sporophyte stage. Double fertilization is an event unique to angiosperms. One sperm in the pollen fertilizes the egg, forming a diploid zygote, while the other combines with the two polar nuclei, forming a triploid cell that develops into a food storage tissue called the endosperm. Flowering plants are divided into two main groups, the monocots and eudicots, according to the number of cotyledons in the seedlings. Basal angiosperms belong to an older lineage than monocots and eudicots.



sac-like structure at the tip of the stamen in which pollen grains are produced


phylum to which angiosperms belong

basal angiosperms

a group of plants that probably branched off before the separation of monocots and eudicots


whorl of sepals


single unit of the pistil


collection of petals


primitive leaf that develop in the zygote; monocots have one cotyledon, and dicots have two cotyledons


(also, eudicot) related group of angiosperms whose embryos possess two cotyledons


thin stalk that links the anther to the base of the flower


(also, carpel) structure that constitute the female reproductive organ


grass-like plant noticeable by the absence of woody tissue


related group of angiosperms that produce embryos with one cotyledon and pollen with a single ridge


chamber that contains and protects the ovule or female megasporangium


part of the plant consisting of the calyx (sepals) and corolla (petals)


modified leaf interior to the sepals; colorful petals attract animal pollinators


fused group of carpels


modified leaf that encloses the bud; outermost structure of a flower


structure that contains the male reproductive organs


uppermost structure of the carpel where pollen is deposited


long, thin structure that links the stigma to the ovary

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