Cultures with Melampsorae on Populus

Summary

The results of the present investigation show that the rusts on Populus which were heretofore distinguished as Melampsora medusae and M. albertensis will infect both Pseudotsuga and Larix. In the absence of sharp differential characters between these two forms, both in their gross and minute details, it is suggested that they are the different host manifestations of the same rust and should apparently be referred to Melampsora medusae Thüm.

Two new hosts for this rust are recorded, viz., Larix lyalli and Pseudotsuga macrocarpa.

New and interesting features attending the production of pycnia in the Melampsorae are reported.