Vegetative and sexual life-history attributes of Chamerion angustifolium (fireweed) as influenced by arbuscular mycorrhizal fungi

Fireweed [Chamerion angustifolium (L.) Holub, formerly Epilobium] typically establishes on sites with reduced levels of arbuscular mycorrhizal fungi (AMF). Although fireweed can establish mycorrhizas, empirical observations coupled with information regarding its ecology suggested a possible detrimental influence of AMF on its growth. This thesis investigated the effect of AMF on vegetative and sexual life-history attributes of fireweed through two controlled greenhouse experiments. AMF were found to have a growth-promotive effect on both above- and below-ground structures of fireweed. These increases in growth, such as augmentation of leaf area, total root length and dry biomass, were most pronounced when the plant-fungal association was begun at the seedling stage. Introductions of the fungi to progressively older plants resulted in much fewer influences on growth, and included some growth impairment. Overall, however, and in contrast to any predictions that were made, fireweed did not appear to be disadvantaged by associating with AMF.