n 1  cap  :  a genus (family Asclepiadaceae) of perennial herbs found chiefly in No. America with flowers having a corona of five concave hoods each of which bears a slender horn - see BUTTERFLY WEED MILKWEED   2  :  any plant of the genus Asclepias  3  :  the dried root of the butterfly weed formerly used as a diaphoretic and expectorant - called also pleurisy root 
Aesculapius see STAFF OF AESCULAPIUS.
 
   
 
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