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Although since the Cretaceous Period (about 145 million to 66 million years ago) gymnosperms have been gradually displaced by the more recently evolved angiosperms, they are still successful in many parts of the world and occupy large areas of Earth’s surface. Gymnosperms were dominant in the Mesozoic Era (about 252.2 million to 66 million years ago), during which time some of the modern families originated ( Pinaceae, Araucariaceae, Cupressaceae). Taxonomists recognize four distinct divisions of extant (nonextinct) gymnospermous plants- Pinophyta, Cycadophyta, Ginkgophyta, and Gnetophyta-with 88 genera and more than 1,000 species distributed throughout the world. The seeds of many gymnosperms (literally, “naked seeds”) are borne in cones and are not visible until maturity. Gymnosperm, any vascular plant that reproduces by means of an exposed seed, or ovule-unlike angiosperms, or flowering plants, whose seeds are enclosed by mature ovaries, or fruits.

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#Pine young staminate cone xylem phlo how to

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