What is Angiosperms?

Angiosperms are the second major group of plants that bear seeds. Angiosperms (seeds in vessels) differ from gymnosperms in that their seeds develop within enclosed vessels of tissue called carpels. Carpels are the parts of organs that are commonly called flowers. In fact, angiosperms are the "flowering plants."

Angiosperms make up most of the plant species alive today. There is a huge diversity of flowering plants today compared to the conifers. It is apparent that the angiosperms evolved special mechanisms that helped them to survive and to reproduce in a rapidly changing Earth environment.

Some scientists believe that insect-mediated pollination played a large factor in the rapid and successful evolution of the flowering plants. Insect pollination is relatively efficient, and it is very selective, in that insects may exhibit a preference for a given species of flower. Seeds are also dispersed effectively by animals, which eat the fruits in which seeds are borne.

There are two major groups of flowering plants: monocotyledons and dicotyledons. Monocotyledons, or monocots, have one food storage area (seed leaf) in each seed, while dicotyledons, or dicots, have two in each seed. Monocots have parallel venation in their leaves, in contrast to the netted venation in dicot leaves. Monocots also have flowers in which the number of petals, sepals, stamen, and carpels is three. Dicots, on the other hand, have flowers in which the number of petals, sepals, stamen, and carpels is either 4 or 5.