Stomatal

The leaves are spirally arranged but slightly twisted at the base to be upswept above the shoot, needle-like, 2–3 cm long, gray-green to blue-green above with a single broad stomatal patch, and with two whitish stomatal bands below.

This isotope ratio allows reviewing the relation of the trees' rate of photosynthesis and the stomatal conductivity, i.e., the photosynthetic rate of trees in comparison to water use.

This study found that when carbon dioxide levels increase from 400 to 600 ppm, cassava leaves could conserve 58 percent more water on average by optimizing stomatal conductance, which is the rate that carbon enters compared to water exiting the leaf.

The increase in vascular bundle thickness further seems to correlate with the width of plant axes, and plant height; it is also closely related to the appearance of leaves and increased stomatal density, both of which would increase the demand for water.