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种子的结构分哪两类每类各举一例

更新时间: 2020-10-29 00:00:00     

种子的结构分两类有:胚乳种子(大部分是单子叶,如玉米)与无胚乳种子(大部分双子叶,如菜豆)。种子是种子植物的胚珠经受精后长成的结构,一般有种皮、胚和胚乳等组成。胚是种子中最主要的部分,萌发后长成新的个体。胚乳含有营养物质。种子是裸子植物、被子植物特有的繁殖体,由胚珠经过传粉受精形成。

关键词: 种子 结构

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