Pedicularis
canadensis grows in large oval patches that advance outward at a
considerable rate. Our working hypothesis is that the hemiparasite
acquires nitrogen from its hosts and thereby exerts a control upon the
surrounding community that results in an enhancement of the hemiparasite's
gains via photosynthesis. Since the parasitism is enhancing
photosynthesis, this type of hemiparasitism is not a way-station to
holoparasitism.