Aecial

1984, D. E. Harder, 11: Developmental Ultrastructure of Hyphae and Spores, William Bushnell, Alan P. Roelfs (editors), The Cereal Rusts: Origins, Volume I: Specificity, Structure, and Physiology, page 355, In the inner wall facing the aecial cavity, the primary wall materials surrounding the processes disintegrate, partially exposing them.

Aecial hosts are primarily conifers. Damage to some aecial hosts may also be considered important, as in pine twist rust caused by M.^([Melampsora]) pinitorqua Rostrup.

The uredo- and teleuto-stages occur on wheat, barley and some grasses and the pycnidial and aecial stages on species of Berberis and Mahonia, the alternate hosts.