# 單子葉植物

| 单子叶植物 化石时期：
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| --- |
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| 科学分类  |
| 界： | 植物界 Plantae |
| 演化支： | 维管植物 Tracheophyta |
| 演化支： | 被子植物 Angiosperms |
| 演化支： | 核心被子植物 Mesangiospermae |
| 演化支： | **单子叶植物 Monocots** |
| 分支
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| * 菖蒲目 Acorales
* 澤瀉目 Alismatales
* 天門冬目 Asparagales
* 薯蕷目 Dioscoreales
* 百合目 Liliales
* 露兜樹目 Pandanales
* 無葉蓮目 Petrosaviales
* 鴨跖草类 commelinids
	+ 棕櫚目 Arecales
	+ 鸭跖草目 Commelinales
	+ 禾本目 Poales
	+ 薑目 Zingiberales
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| 異名
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| * 单子叶植物纲 Monocotyledoneae
* 百合纲 Liliopsida
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**单子叶植物**（Monocotyledons，簡稱monocots），舊名**單子葉植物綱**（Monocotyledoneae）或**百合綱**（Liliopsida）。

單子葉植物包含逾60,000個物種，當中最大的科是蘭科，有超過31,000個物種。

## 特征

单子叶植物种子内的胚只有一片顶生子叶，主根不发达，因此多鬚根；茎内维管束散生，没有排列成形成层，因此不能依靠形成层发育逐渐加粗；叶脉通常是平行脉或弧形脉，因此叶子较长；花的蕊和瓣數一般是3的倍數（如3瓣、6瓣等），也有极少数為4的倍数，但絕不會是5的倍數。花粉具有单个的萌发孔。

## 分类

依被子植物种系发生学组（APG）的分类，现有的单子叶植物分类如下：

* **单子叶植物分支 monocots**
菖蒲目 Acorales
泽泻目 Alismatales
天門冬目 Asparagales
薯蕷目 Dioscoreales
百合目 Liliales
露兜树目 Pandanales
无叶莲目 Petrosaviales
 **鸭跖草类植物 commelinoids**
棕榈目 Arecales
鸭跖草目 Commelinales
禾本目 Poales
薑目 Zingiberales

### 沿革

在传统的克朗奎斯特分类法中，单子叶植物被称做“百合纲”，和双子叶植物的木兰纲并立。其中包括了兰目这个大目。

但后来的研究逐渐让植物学家认知，单子叶植物实际是由古代的双子叶植物演化而来，是双子叶植物的其中一个特化分支，这使传统的双子叶植物分类成为一个并系群而不再被视为有效分类。

APG分类法对被子植物的基因研究确定单子叶植物是被子植物分支之下的一个单系群分支，分类有效，并设立了**单子叶植物分支**，内部分类则有许多变动，包括否定了兰目这个多系群分类，并成立了天門冬目、薯蓣目等新目。

2003年经过修订的APG II 分类法也使用这种分类方法，包括传统分类中所有单子叶植物纲中的植物种类。

APG II 分类法将单子叶植物分支中的植物分为10个目和2个单独的科， 其中部分目列入鸭跖草分支（一 个基因亲缘群体）。

2009年修订的APG III分类法又将单独的无叶莲科（Petrosaviaceae）提升为无叶莲目（Petrosaviales）。

2016年修订的APG IV 分类法将多须草科归于棕榈目。

### 系统发生学

单子叶植物在被子植物中的演化位置以及其下各分支的亲缘关系如下：

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 被子植物
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 核心被子植物
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| **单子叶植物** |

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 鸭跖草类
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鸭跖草目

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姜目

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禾本目

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棕榈目

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天门冬目

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百合目

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薯蓣目

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露兜树目

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无叶莲目

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泽泻目

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菖蒲目

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金鱼藻目

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真双子叶植物

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木兰类

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金粟兰目

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木兰藤目

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睡莲目

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无油樟目

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* 被子植物分类学网（APWeb）：單子葉植物（英文）