裸子植物(gymnosperm)

藉种子繁殖，胚珠和种子裸露的种子植物（这点与被子植物不同，被子植物的种子由果实包裹）。包括四个现存的门：球果门、凤尾蕉门、买麻藤门和银杏门。一半以上的裸子植物为乔木，其余种类中的大部分为灌木。裸子植物见於南极以外的所有大陆，尤其是温带地区。广布於北半球的种类是桧、枞、落叶松、云杉和松。南半球分布最广的裸子植物是罗汉松。裸子植物的木材常称作软材，不同於被子植物的硬材。许多材用树及纸浆用树亦栽作观赏树，仅少数裸子植物可供食用。云杉、松和铁杉等可提取精油，用於肥皂、空气清新剂、消毒剂、药物、化妆品、香料等。云杉和铁杉可提取丹宁用於制革。松脂是产自松树的含油树脂，加工後可制成松节油及松香。裸子植物是古代植被的主要成分，这些植被压在地下数百万年以後变成了煤层。大部分裸子植物为常绿树，裸子植物能产生雌、雄生殖细胞（大孢子及花粉粒），分别位於球果状的雌、雄孢子叶球中。

English version：

gymnosperm

Any woody plant that reproduces by means of a seed (or ovule) in direct contact with the environment, as opposed to an angiosperm, or flowering plant, whose seeds are enclosed by mature ovaries, or fruits. The four surviving gymnosperm divisions are Coniferophyta (conifers, the most widespread), Cycadophyta (cycads), Ginkgophyta (ginkgos), and Gnetophyta. More than half are trees; most of the rest are shrubs. Gymnosperms occur on all continents except Antarctica, and especially in the temperate latitudes. Those widely found in the Northern Hemisphere are junipers, firs, larches, spruces, and pines; in the Southern Hemisphere, podocarps (Podocarpus). The wood of gymnosperms is often called softwood to differentiate it from the hardwood of angiosperms. Many timber and pulp trees are also planted as ornamentals. Gymnosperms also are a minor source of food; of essential oils used in soaps, air fresheners, disinfectants, pharmaceuticals, cosmetics, and perfumes; of tannin, used for curing leather; and of turpentines. Gymnosperms were a major component in the vegetation that was compressed over millions of years into coal. Most are evergreen. They produce male and female reproductive cells in separate male and female strobili (see cone).

参考文章

• 裸子植物Gymnosperm地球科学