Seed plants begin life as an embryonic plant inside the covering of a seed. When watered, the seed germinates and as it begins to root and flower, it can produce new seeds. The two major categories of seed plants are angiosperms (with covered seeds) and gymnosperms (naked seeds).
There are 260,000 angiosperms, which are flowering plants according to Tolweb.org. Gymnosperms were popular during the days of the dinosaur and still exist today. For example, in California the Giant Redwood is 2,000 years old and the Bristle Cone Pine Trees is 5,000 years old.
"Angiosperms are crucial for human existence; the vast majority of the world's crops are angiosperms, as are most natural clothing fibers. Angiosperms are also sources for other important resources such as medicine and timber," says Tolweb.org. They also state that 132 million years ago, a variety of angiosperms, both small and large were around, comparable to magnolias.
Some examples are Magnolia, Foxglove, Jasmine, Hyacinth, Marigolds, Sunflower, Begonia, Violets, Butterfly Bush, Zinnia, Bells of Ireland, Forget Me Not, Bluebell, Daisy, Pincushions, Sage, Lupine, Carnation and Peony.
Flowerless seed plants are called gymnosperms. "Conifers are common gymnosperms; instead of flowers, conifers have cones that produce pollen or eggs," says Teachersdomain.org.
"The world and human civilization would be very different if there were no pines, redwoods, spruces, and other gymnosperms. These trees form extensive forests in many cooler and colder regions of the world. These forests provide lumber for millions of homes, wood for many other uses, most of our paper, and habitat for many species of wildlife. These forests improve the air we breathe, producing oxygen and storing carbon dioxide," says Margaret Connolly and Christopher Campbell, University of Maine.
Some common gymnosperms are Cycads, Pines, Firs and Ginkgo/Maidenhair Tree. Type of Coniferous trees include Japanese Cedar, Spiny Greek Juniper, Incense Cedar, Monkey Puzzle, White Spruce, Golden Larch, Giant Sequoia, Umbrella Pine, Western Hemlock, American Arborvitae and English Ewe.
Are All Plants Alike?
Not all plants are seed plants; mosses and ferns reproduce with spores that later develop into new plants. According to Teachersdomain.org "Unlike seeds, spores are produced without fertilization and contain neither a plant embryo nor endosperm. Some plants can reproduce without spores or seeds through vegetative reproduction, in which a part of the stem or root gives rise to a new plant."