Studies on the origin, evolution, and distribution of the Gramineae. IV. The genus Poa L
Studies on the origin, evolution, and distribution of the Gramineae. IV. The genus Poa L
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DOI：
10.1071/bt9610152
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发表时间：
1961-01-01
期刊：
影响因子：
--
通讯作者：
HARTLEY, W.
中科院分区：
文献类型：
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作者：
HARTLEY, W.
早熟禾属Poa L.在高纬度和高海拔地区，其相对种间分化达到最高。该属在热带地区是不存在或稀有的，除了在山区，但构成超过15%的草植物群的阿拉斯加，冰岛，堪察加半岛，和高帕米尔山脉。早熟禾物种的高百分比频率与凉爽的夏季温度有关。在美国，75 [degree] F仲夏（7月）等温线有效地划分了早熟禾属植物生长的地区。从它们在其中构成较小百分比的那些植物中形成超过5%的草植物群。在世界其他大多数地区，也发现了类似的百分比频率和仲夏温度之间的关系。温度以外的气候因子对早熟禾的分布影响不大。该属已达到一个高的发展阶段，在世界上几乎所有的地方，它是气候适应。证据不允许关于该属起源中心的确切结论，但它在中亚的山区和高原地区有一个主要的物种分化中心。它可能是单系的，并且有很长的进化历史，在此过程中，它已经传播到现在被地形或气候障碍所分隔的地区。|| 摘要编辑：作者
The genus Poa L. reaches its highest relative specific differentiation in regions of high latitude and high altitude. The genus is absent or rare in the tropics, except in mountainous regions, but constitutes more than 15% of the grass flora of Alaska, Iceland, Kamchatka, and the high Pamir Mountains. High percentage frequencies of species of Poa are associated with cool summer temperatures. In the United States the 75[degree]F mid-summer (July) isotherm effectively demarcates those regions in which Poa spp. form more than 5% of the grass flora from those in which they constitute a smaller percentage. A similar relationship between percentage frequency and mid-summer temperature is found in most other parts of the world. Climatic factors other than temperature seem to have little influence on the distribution of Poa. The genus has attained a high stage of development in nearly all parts of the world to which it is climatically adapted. The evidence does not permit firm conclusions about the centre of origin of the genus, but it has a major centre of species differentiation in the mountain and plateau region of central Asia. It is probably monophyletic, and has had a long evolutionary history in the course of which it has spread through regions now separated by topographical or climatic barriers. || ABSTRACT AUTHORS: Author