| hanacis taraxaci (Ashmead) induces rapidly growing, structurally simple galls on the leaves of the common dandelion Taraxacum officinale (L.).;The anatomical study of ungalled dandelion leaves determined one prominent anatomical difference between immature and mature leave: the number of vascular bundles with the midrib. Midribs of immature leaves contain three major vascular bundles on the abaxis and four to five minor bundles on the adaxis. As leaves mature, five major vascular bundles are found on the abaxis and seven to nine on the adaxis.;Phanacis taraxaci induces both single- and multichambered galls within tissues of the midrib, at various stages of development. Three phases of gall development were identified; initiation, growth, and maturation. Gall initiation is extremely rapid compared to other cynipids, lasting approximately 60-62 hours post-ovipostion. Eggs hatch approximately 60 hours post-oviposition and soon after proliferation of gall parenchyma increases evenly around the larval chamber. This increase in parenchyma poliferation signals the completion of gall initiation and the onset of gall growth. Gall growth is also extremely rapid, lasting 12 to 14 days. Nutritive cells first appear approximately 70 hours post-oviposition and a complete nutritive zone surrounds the larval chamber Day 8. Once the galls reach maturity, between Days 25 to 30, they turn brown, desiccate, become corky and fall to the ground along with their senesced host leaf.;Galls of P. taraxaci are physiological sinks for photoassimilates accumulating 9% to 70% of the total carbon produced by the host, depending upon the number of galls per plant. Active assimilation... |
