浮萍

水生漂浮植物浮萍(duckweeds)，隶属于天南星科 亚科(Lemnoideae), 包含5个属, 37个种:

• 紫萍属(Spirodela) 2个物种；
• 少根紫萍属(Landoltia) 1个物种；
• 青萍属(Lemna) 13个物种；
• 扁无根萍属(Wolffiella) 10个物种；
• 芜萍属(Wolffia) 11个物种；

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其中，
（1）紫萍 是最古老、个体最大的浮萍物种；
（2）芜萍 是个体最小、最后进化出的浮萍物种；

Schematic diagram of Landotia punctata 常见5个浮萍物种的外部形态

(a1) 紫背浮萍(Spirodela polyrhiza), 约5~11个根;
(a2) 少根紫萍(Landoltia punctata), 仅1个根;
(a3) 青萍(Lemna minor), 仅1个根;
(a4) 稀脉浮萍(Lemna aequinoctialis), 仅1个根;
(a5) 芜萍(Wolffia globosa), 无根.

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冷泉港实验室对

• 青萍(L. minor 8627, 约800 Mb)、
• 青萍(L.gibba 7742a, 约450 Mb)和
• 芜萍(Wolffia australiana 8730)

也进行了基因组测序, 已有的基因组数据公布在 https://www. Lemna.org 网站上.

Evolution of Root Development.
A major difference between land and aquatic plants is the intake pathway of water and nutrients. The Spirodela sticky root system appears to be more critical for securing an anchoring position and promoting a wide distribution rather than absorbing nutrients. It was reported that the lower surface of the frond served as the main organ for nutrient uptake.

When the lower surface was painted with waterproof lanolin, duckweeds grew more slowly than control plants (http://www.missouribotanicalgarden.org). As we cut the roots from mother fronds, Spirodela continued to grow by producing daughter fronds after 3 d, keeping pace with the control plants bearing intact roots. Spirodela has as many as 12 adventitious roots (ARs,不定根) per frond but lacks secondary lateral roots (LRs，侧根) and root hairs (RHs)

界	植物界	Kingdom	Plantae
门	被子植物门	Phylum	Angiospermae
纲	单子叶植物纲/木兰纲	Class	Monocotyledoneae/Magnoliopsida
目	泽泻目	Order	Alismatales
科	天南星科	Family	Araceae
属	浮萍属	Genus	Lemnoideae
种		Species

https://baijiahao.baidu.com/s?id=1690673690233519907&wfr=spider&for=pc