Question #3cdd0

1 Answer
Mar 3, 2014

Plants are classified according to how they reproduce. Angiosperms and gymnosperms both reproduce through bearing seeds, though in different forms. Pteridophytes reproduce through spores.

Pteridophytes or Pteridophyta, are vascular plants that reproduce and disperse via spores. Because they produce neither flowers nor seeds, they are referred to as cryptogams. The group includes ferns, horsetails, clubmosses, spikemosses and quillworts. These do not form a monophyletic group, because ferns and horsetails are more closely related to seed plants than to lycophytes. Therefore, pteridophytes are no longer considered a valid taxon, but the term is still used as an informal way to refer to ferns (monilophytes) and lycophytes or even only to monilophytes.

Gymnosperms are vascular plants that reproduce by means of an exposed seed, or ovule, as opposed to an angiosperm, or flowering plant, whose seeds are enclosed by mature ovaries, or fruits. The seeds are produced through cone-like 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." Their reproductive structures are flowers in which the ovules are enclosed in an ovary. It is believed that angiosperms are the most advanced of the plant kingdom. They are found in almost every habitat from forests and grasslands to sea margins and deserts. They display a huge variety of life forms including trees, herbs, submerged aquatics, bulbs and epiphytes, including all edible food consumed by humans and animals. The largest plant families are Orchids, and Compositae (daisies) and Legumes (beans).

The following is a chart that compares the ways in which mosses, ferns, gymnosperms, and angiosperms have adapted to a land environment.