Coordination between the density of veins (water supply) and stomata (demand for water) has been found in the leaves of modern angiosperms and also in ferns. This suggests that this coordinated development is not a unique adaptation of derived angiosperms that enables their high productivity. To test this, we compiled leaf vein and stomatal density data from 520 land vascular plant species including derived angiosperms, basal angiosperms, gymnosperms and ferns. We found global coordination across vascular land plants, although the relationships were not significant in gymnosperms and vessel-less angiosperms. By comparing the evolution of xylem conduit elements with variation in the density of veins and stomata and theoretical stomatal conductance among plant lineages, we found that the physiological advantage of modern angiosperms is associated with the emergence of xylem with low intraconduit resistance and leaves with high vein and stomata densities. Thus our results indicate two major events associated with surges in xylem hydraulic capacity in angiosperms: (1) the origin of vessels and (2) the emergence of vessels with simple perforation plates, which diminished physical limitations on stomatal conductance. These evolutionary innovations may have enabled derived angiosperms to be more productive and adaptive to the changing climate.

在现代被子植物的叶子和蕨类植物中都发现了静脉（供水）和气孔（对水的需求）之间的协调。这表明这种协调的发展并不是衍生的被子植物能够使其高生产力的独特适应。为了对此进行测试，我们收集了520种陆地维管植物物种（包括衍生的被子植物，基被子植物，裸子植物和蕨类植物）的叶静脉和气孔密度数据。尽管在裸子植物和无血管被子植物中这种关系并不显着，但我们发现在维管植物上具有全球协调性。通过比较木质部导管元件在植物谱系之间的变化，静脉和气孔密度以及理论气孔导度的变化，我们发现，现代被子植物的生理优势与导管内阻力低的木质部的出现和静脉和气孔密度高的叶片的出现有关。因此，我们的结果表明与被子植物木质部水力增加有关的两个主要事件：（1）血管的起源和（2）带有简单穿孔板的血管的出现，这减少了对气孔导度的物理限制。这些进化的创新可能使衍生的被子植物更具生产力，并适应不断变化的气候。（1）血管的起源和（2）带有简单穿孔板的血管的出现，减少了气孔导度的物理限制。这些进化的创新可能使衍生的被子植物更具生产力，并适应不断变化的气候。（1）血管的起源和（2）带有简单穿孔板的血管的出现，减少了气孔导度的物理限制。这些进化的创新可能使衍生的被子植物更具生产力，并适应不断变化的气候。