References for Optimal defense in wild parsnip

Hendrix, S.D. 1979. Compensatory reproduction in a biennial herb following insect defloration. Oecologia 42:107-118.

Zangerl, A.R. 1986. Leaf value and optimal defense in Pastinaca sativa L.   (Umbelliferae). American Midland Naturalist 116:432-436.

Zangerl, A.R., and M.R. Berenbaum. 1987. Furanocoumarins in wild parsnip: effects of photosynthetically active radiation, ultraviolet              radiation, and nutrients. Ecology 68:516-520.

Nitao, J.K., and A.R. Zangerl. 1987. Floral development and chemical defense allocation in wild parsnip (Pastinaca sativa). Ecology 68:521-529.

Zangerl, A.R., and C.E. Rutledge. 1996. Probability of attack and patterns  of constitutive and induced defense: a test of optimal defense theory.           American Naturalist 147:599-608.