Water is factor is V. Thapsus. The plant has adapted for it by creating a deep root system that in the first year is significantly larger than the plant mass above ground. The first year of this plant the root system is the main priority, the leaves stay flat and spread out horizontally. The second year the storage in the roots is used to grow the plant up wards and to produce flowers. The tap root is shown in the below picture.
The leaves are also adapted for reducing water loss. The leaves are hairy which, as we learned in class reduce airflow over the stomata, this decreases the water evaporation. The plant's petiole is relatively thick, and hairy as well. The thickness is due to large xylem and vascular tissues to transport the water to the leaves for evaporation. They are hairy to avoid excess evaporation with respirating. The entire plant is very well adapted for the low moisture of the prairie.
The light color of the hairs reflects light, keeping the plant cool t also prevent excess water loss.
The light color of the hairs reflects light, keeping the plant cool t also prevent excess water loss.
Great picture of a taproot! Interesting that it invests so much in its roots the first year…. What kind of soil does this plant grow in? Why is water limiting – is the habitat dry seasonally or year-round?
ReplyDeleteIt grows in sandy, dry, "well drained" soil. It grows in the prairies in the Midwest. Which has very limiting water.
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