Biology 1st Edition by Jerome Krueger, Kendra Hill, Robert Noyd

Exercise 9

Burdock is an herbaceous biennial that lives in fields and pastures. It was the inspiration for the hook-and-loop fabric fastener (Velcro®). In nature, its adaptive hooks catch and tightly stick to a passing animal's fur. The animal carries the burr some distance before it stops to remove it. Look at Figure and determine whether this adaptation is one of the burdock's receptacle, fruit, or seed. How would the height of the stem affect the kinds of animals that disperse the burr? Would a large- or small-sized burr be favored to move the burr out from the seed shadow? Explain.
Figure Burdock fruits.