[农学]被子植物门1.ppt

被子植物门Angiosperm The flowering plants or angiosperms are the most widespread group of land plants . The flowers of flowering plants are the most remarkable feature distinguishing them from other seed plants. Closed carpel enclosing the ovules (carpel or carpels and accessory parts may become the fruit) 弗吉尼亚木兰 (Magnolia virginiana， 一种开芳香白花的木兰). 被子植物门 特点： 1 被子植物具有典型的花，胚珠包藏于由心皮密封而成的子房中，而不裸露，即包被起来。 2 叶片都宽大，网状脉或平行脉，被子植物门也称阔叶树。分两类：一类是阔叶树分布在热带亚热带,另一类落叶阔叶树，分布温带。 3 被子植物胚中子叶(cotyledon)1或2，根据子叶数目不同分两个纲：单子叶植物纲(monocotyledon)和双子叶植物纲地(dicotyledon)。 分类 The number of species of flowering plants is estimated to be in the range of 250,000 to 400,000. The diversity of flowering plants is not evenly distributed. Nearly all species belong to the dicot (75%), monocot (23%) and magnoliid (2%) clades. 全世界的被子植物种类有25万种；中国约产2.5万种；其中木本植物8000余种，被子植物分双子叶植物纲和单子叶植物纲。这本书采用恩格勒系统。 双子叶植物纲 Dicotyledons, or dicots, is a name for a group of Folwering plants whose seed typically has two embryonic leaves or cotyledons. Flower: The flower parts in dicots are multiples of four or five Stem: The stem vascular bundles in dicots are in a ring Roots: Taproot system Leaves: In dicots , the major leaf veins are reticulated 双子叶植物纲 多为直根系，网状叶脉，花的各部4-5基数，胚常具2枚子叶，双子叶植物的种类约占被子植物的3/4，其中约有一半的种类是木本植物。 根据花瓣的联合与否，将双子叶植物纲分为离瓣花亚纲和合瓣花亚纲 Ⅰ 离瓣花亚纲 离瓣花亚纲又称古生花被亚纲，是较原始的被子植物。花无被、单被或复被。而以花瓣分离为主要特征。 杨柳科Salicaceae The Salicaceae contained three genera (Salix, Populus and Chosenia) They are all woody (shrubs or trees) Most species of the family are dioecious.? Catkins and capsular fruit Seeds emerging from capsules of the Salicaceae are comose (多毛的)---cottonwood 杨柳科 (1)叶乔木或灌木。（2）单叶互生。 (3)花单性异株，成柔荑花序无花被，单生于苞腋，雄蕊2—多数，子房上位；（4）蒴果2—4裂，种子细小，基部有白色丝状长毛。 共3属，540种，产于温带、亚热带；中国3属，226种，遍及全国，本科植物很容易种间杂交，故分类较为困难。 钻天柳属1种，分布东北，雌花直或斜伸，雄花下垂。 杨属Populus Populus species are medium-sized to large or very large deciduous trees.The bark on young trees is smooth, white to greenish or