How do tumbleweeds tumble?
"The seedling initially grows vertically but usually falls over, creating a 90 degree bend at the root crown.
Subsequently, the stem resumes a vertical growth pattern and eventually becomes woody.
This creates two nearly 90 degree angles in the main stem, which are weak points subject to breaking in strong winds.
As the plant tumbles, twigs break off, carrying at least one seed per node. This seed dispersal method is noteworthy
because seeds seldom fall from the plant otherwise. Landowners who plow or disk to control this pest actually spread
the seeds further and create ideal conditions for them to sprout during the next season. Spine-tipped mature leaves
can cause considerable discomfort to the skin, but young plants can be used as cooked greens." (Oscar Clarke, Riverside botanist)
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