THE UREDINALES FOUND UPON THE ONAGRACEAE 559 
Into the fourth group must be placed the unknowns, Aecidium 
Anograe, Aecidium Circaeae, and Uredo oenothericola. {Puccinia 
sphaeroidea, as discussed previously, may be here omitted.) Uredo 
oenothericola may eventually land in the second group here given. 
Applying certain principles of correlation that have sometimes proven 
serviceable heretofore, one might vaguely prophesy regarding the 
alternate stages of Aecidium Anograe and Aecidium Circaeae. These 
two forms stand rather at extremes of the heteroecious aecial stages 
upon the Onagraceae. Aecidium Anograe has the largest aeciospores, 
and is the only one known possessing thick walls. Aecidium Circaeae 
has the smallest aeciospores, with thin walls. The former might be 
prophesied to go with an alternate form possessing rather large, 
thick-walled urediniospores; the latter, perhaps, with a form having 
small urediniospores. 
Taking up the relation of these rusts to their hosts, a few points 
of interest are evident, in addition to those already presented in other 
connections. The related and cosmopolitan genera Chamaenerion 
and Epilobium harbor rusts that are placed in the first three groups 
just discussed. That there is some relation between the wide dis- 
tribution, and, possibly, greater age of these genera, and the many, 
varied, and widely distributed rusts parasitic upon them, readily 
suggests itself. The most anomalous thing here appears to be the 
occurrence of the one representative of our third group, i. e., Puccinia 
gigantea. 
Another point with respect to hosts, rather out of harmony with 
expectations, is the conspicuous identity of the hosts of the different 
races of Uromyces plumbarius and those of the aecia of Puccinia Peckii. 
These two are not correlated species; and, indeed, as noted, neither of 
the two inhabits a host genus upon which an apparently correlated 
species does occur. The significance of this point seems perplexing 
to the writer. 
Throughout these rusts upon the Onagraceae, wherever collections 
are in hand in sufficient numbers for a considerable comparison, vari- 
ability is to be noted. Although short-cycled species are often found 
to be more constant, yet in the Onagraceae, the one American short- 
cycled species that is well represented in the Arthur herbarium has been 
found variable; it exists as a micro- or lepto-form in different seasons; 
the characters of the sori and teliospores vary. Puccinia Jussiaeae 
shows considerable variation. The marked variability of the autoe- 
cious species ha's been noted. One rather outstanding feature with 
