# 裸子植物

| 裸子植物化石时期：
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| 各种裸子植物
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| 科学分类 |
| 界： | 植物界 Plantae |
| 演化支： | 维管植物 Tracheophyta |
| 演化支： | 真维管植物 Eutracheophyta |
| 演化支： | 真叶植物 Euphyllophytes |
| 演化支： | 放射状植物 Radiatopses |
| 演化支： | 木質植物 Lignophytes |
| 总门： | 种子植物总门 Spermatophyta |
| 並系群： | 裸子植物门 Gymnospermae |
| 传统分类中包含的子类群
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* †種子蕨門 Pteridospermatophyta （並系群）

* 末端裸子植物 Acrogymnospermae

	+ 松柏門 Pinophyta

	+ 銀杏門 Ginkgophyta

	+ 蘇鐵門 Cycadophyta

	+ 買麻藤門 Gnetophyta
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| 传统分类中未包含，但在 演化层面上包含的演化支
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| * 被子植物 Angiosperm
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裸子植物（左）和被子植物（右）胚珠对比
**裸子植物**（學名：Gymnospermae）指通过种子繁殖但胚珠暴露在孢子葉邊緣或葉面的维管植物，有现生的松柏门、银杏门、苏铁门、买麻藤门和已灭绝的种子蕨门共5個門14个科88个屬超過1000个已知物种 。裸子植物这个名称源自希臘語γυμνός (*gumnós*) + σπέρμα (*spérma*)，意为「裸露的種子」，因為裸子植物的胚珠外圍沒有子房壁保護，孢子葉通常會排列成圓錐的形狀；由於孢子葉並不向內卷合包覆胚珠，所以也無子房的構。

裸子植物會在体内產生孢子，有發展成似花粉的「小孢子」和留在胚珠裡的「大孢子」兩種，繁殖时小孢子通过空气飘浮（风媒）或动物（通常为虫媒）离开母体向异体授粉进行有性繁殖。當受精（大孢子和小孢子結合）之後，形成的胚芽便會和其他細胞組成胚珠，並發展成裸露的種子。與種子植物的另一主要類群——被子植物（在支序分类学上被视为从裸子植物下分出的一个演化支）相比，后者的胚珠則是包裹在向內卷合的心皮（一個邊緣相接的胞子葉）內受到保護，且外部配有更利于吸引传粉动物的特化繁殖器官——花，而且子房会发展成营养丰富的果实吸引其它动物（特别是四足类脊椎动物）吞食进一步协助种子传播。

裸子植物起源于3.85亿年前的中泥盆世，因其比蕨类植物更加抗旱而在盘古超大陆整合后气候愈加干燥的晚古生代（泥盆纪和二叠纪）和早中生代（三叠纪）开始繁盛，并在二叠纪末大灭绝后成为陆地生态系统的优势植物类群，但在白垩纪中后期随着被子植物的兴起后丧失了陆地植物相的主流位置，现今只在高纬度林地中仍占主流。

花旗松的毬果
斯氏非洲苏铁的毬果

## 分類

在早期的分類裡，裸子植物被認為是一個「自然」的群體。但是，一些化石的發現猜測被子植物可能演化自一裸子植物的祖先，這將使得裸子植物形成一個並系群，若將所有滅絕的物種都考慮進來的話。現代的親緣分支分類法只接受單系群的分類，可追溯至一共同的祖先，且包含著此一共同祖先的所有後代。因此，雖然「裸子植物」一詞依然廣泛地被使用來指非被子植物的其他種子植物，但之前一度被視為裸子植物的植物物種一般都被分至五個類群中，以讓植物界內的門都有著相同的階層。

考慮其他已滅絕的裸子植物，現存物種的分子種系發生學已和其對於開花植物是組成一單系群或併系群的形態類別相衝突。而還在爭議上的還有，買麻藤門會是被子植物的旁支，亦或是其他已滅絕的裸子植物之旁支，或同源。

### 種系發生學

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| 种子植物 Spermatophyta
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†Moresnetiopsida Doweld 2001 |
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†Lyginopteridopsida Novák 1961 emend. Anderson, Anderson & Cleal 2007 |
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†皱羊齿目 Pachytestopsida Doweld 2001 |
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†华丽木目 Callistophytales Rothwell 1981 emend. Anderson, Anderson & Cleal 2007 |
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†盾籽目 Peltaspermopsida Doweld 2001 |
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†Umkomasiales Doweld 2001 |
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| 末端裸子植物 Acrogymnospermae
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苏铁门Cycadophyta

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银杏门 Ginkgophyta

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买麻藤门 Gnetophyta

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松柏门 Pinophyta

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†Phasmatocycadopsida Doweld 2001 |
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†Pentoxylopsida Pant ex Doweld 2001 |
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†Dictyopteridiopsida Doweld 2001 |
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†Cycadeoideopsida Scott 1923 |
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†开通目 Caytoniopsida Thomas ex Frenguelli 1946 |
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被子植物 Angiosperms

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 | **裸子植物** Gymnospermae（并系群）
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## 備註

## 參考文獻

### 引用

### 来源

* Bowe, L. Michelle, Gwénaële Coat, and Claude W. dePamphilis. 2000. Phylogeny of seed plants based on all three genomic compartments: Extant gymnosperms are monophyletic and Gnetales' closest relatives are conifers. *Proceedings of the National Academy of Sciences* 97: 4092-4097 (abstract（页面存档备份，存于互联网档案馆）).
* Soltis, Douglas E., Pamela S. Soltis and Michael J. Zanis. 2002. Phylogeny of seed plants based on evidence from eight genes. *American Journal of Botany* 89: 1670-1681 (abstract).
* Chaw, Shu-Miaw, Christopher L. Parkinson, Yuchang Cheng, Thomas M. Vincent, and Jeffrey D. Palmer. 2000. Seed plant phylogeny inferred from all three plant genomes: Monophyly of extant gymnosperms and origin of Gnetales from conifers. *Proceedings of the National Academy of Sciences* 97: 4086-4091 (abstract（页面存档备份，存于互联网档案馆）).

* The Gymnosperm Database（页面存档备份，存于互联网档案馆）