OBSERVATIONS ON FOREST TREE RUSTS 329 
conspicuous by its appearance on the second year needles of its host, 
by its white aeciospores and unusually long peridia. Most of the 
other needle rusts occurring on conifers occupy the needles of the 
season and this fact is accounted for by the overwintering of the telial 
Fig. I. Uredinopsis pteridis. I stage on Abies grandis showing appearance 
upon second year needles. 
Stage. The infection of these Peridermia is produced in the spring on 
the youngest needles and the fungi mature the same year. This 
Peridermium has its alternate stages upon Pteridiiim aquilinum 
pubescens Underw. (fig. 2) and the conclusion is that the telial stage 
does not winter over as is the common habit of such rusts. The needles 
