Characteristics of gymnosperms and angiosperms and pterdophytes
Ferns come in a wide variety of sizes. Some are 1 inch tall and others grow to be 65 feet tall. There are two stages of the fern's life cycle known as alternation of generations, called asexual and sexual. In the asexual stage the fern is known by botanists as a sporophyte. During this stage, the leaves produce sporangia, the dark spots found on the underside of the fronds. Once the plant matures, thousands of spores are released from the sporangia to be carried on the breeze to fertile soil, to begin the sexual stage of the fern, as a plant known by botanists as a gametophyte. This plant is seldom seen as it only lives for a few weeks. It is in this stage that both male and female reproductive parts are developed in the plant.Gymnosperms
Gymnosperms are seed-bearing plants. The seeds are produced through conelike structures instead of inside a fruit or fleshy covering. The name "gymnosperm" derives from the Greek for "naked seed." It is believed that gymnosperms evolved from the primeval ferns that produced seeds. The wide majority of gymnosperms are conifers, such as pine trees, fir, cedar and juniper. Other types are called cycads, and the one that has a single surviving species is the gingko. Many types of trees and shrubs are classified as gymnosperms.
Angiosperms are the flowering plants, which produce their seeds through flowers and fruits. The name comes from the Greek for "vessel" and "seed." It is believed that angiosperms are the most advanced of the plant kingdom. Most of the plants throughout the world fall into this classification, including all edible food consumed by humans and animals.