Veins tell it all

JUST LIKE the circulatory system in humans, leaf veins are the lifeline of plants. The varied networks of veins in terms of shapes, sizes and thickness decide leaf economics. Scientists have shown vein patterns also control carbon and water absorption in plants.

Benjamin Blonder of University of Arizona and his team analysed leaves of 2,500 plant species and prepared a mathematical model. The model shows spacing in the vein skeleton controls the amount of water the veins can supply, vein density controls the amount of CO₂ absorbed by the leaf, and loopy veins determine how resistant the leaf is to external damage. These traits vary between species, the researchers noted in the November issue of Ecology Letters.

For instance, Blonder said, leaves of corn and rice have less venation spacing and high vein density. This suggests the plants have high water and carbon fluxes. The loopy venation of mango leaf protects it from tear. Leaves that have closely knit veins absorb more CO₂. “But this does not mean we should plant trees with dense vein networks to save the planet,” he added.

The different patterns help the plant adjust to a variety of environment. For instance, plants in extreme climates have dense venation to enable them retain CO₂ and water for long. Venation on fast growing plants are usually less dense and less loopy to carry water and CO₂ faster. This aids in high photosynthetic rate and quick food production.

In India, most crops have short route vein networks as it means more water and carbon uptake and ultimately more food production, Blonder added.

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