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Silphium perfoliatum L. Asteraceae Indian Cup. Distribution: North America. Austin (2004) records that another species, S. compositum, was used by Native Americans to produce a chewing gum from the dried sap of the roots, and Native American medicinal uses for 'Indian Cup' are probably referrable to S. compositum and not S. perfoliatum. Silphium perfoliatum contains enzymes that inhibit trypsin and chymotrypsin which gives it resistance to fungal, bacterial and insect attacks. Male gall wasps (Antisotrophus rufus) alter the chemistry of the plant to enable them to locate females, making it a 'signpost' plant. The gall wasp lays its eggs in the stem of Silphium laciniatum, to provide food for the larva on emergence, and the galls containing a male or a female wasp will cause the plant to give off a different chemical odour. Emerging male wasps can search for female wasps, which emerge later, by locating this chemical fragrance which acts as a sex pheromone proxy (Tooker et al Proc Natl Acad Sci U S A. 2002 Nov 26
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