444 AMERICAN JOURNAL OF BOTANY [Vol. 8. 
and forming teliospores to replace those which have germinated; while in 
Aplopsora Nyssae the teliospores are all formed and matured at practically 
the same time without subsequent spore production. 
Fig. 3. Section through mature telium of Aplopsora Nyssae showing arrangement of 
spores in one layer. 
Just what the complete life cycle of Aplopsora Nyssae may be is difficult 
to say. The early germination of the teliospores without a resting period, 
if this rust is autoecious, would apparently necessitate the production of 
pycnia and aecia or pycnia and uredinia immediately following infection or 
else the development of a systemic mycelium from which such stages would 
be produced the following spring. The herbarium material available does 
not show either condition and it is probable that this rust is heteroecious. 
The aecial stage and probable aecial hosts cannot be foretold definitely. 
The related genus, Melampsora, has for its aecial stage a Caeoma with 
either subcuticular or subepidermal pycnia. The alternate hosts belong 
to a number of genera, mostly, however, conifers. Chnoopsora has for its 
aecial stage a Caeoma with subcuticular pycnia, the species with known 
life cycle being autoecious. Melampsoridium Betulae (Schum.) Arth. has 
a peridermium with subcuticular pycnia on Larix. In consequence it 
would be expected that Aplopsora Nyssae would have a Caeoma or a 
Peridermium for its aecial stage, probably upon some conifer. Specimens 
of Caeoma strohilina Arth. on pine are in the Arthur herbarium from Gulfport 
and Agricultural College, Mississippi, which may possibly be the alternate 
stage of the Nyssa rust. Hedgcock and Hunt^ have reported connecting 
this rust with a Uredo on Quercus from material collected in Florida. 
They, however, mention that some of the collections of Caeoma strohilina 
have pseudoperidia and that another rust is represented here, which is 
unconnected. There is also the possibility that this rust may produce a 
Peridermium on pine which is at present confused with one of the many 
species of Peridermium found in the south. 
The second rust occurs on Urticastrum divaricatum and was received by 
Dr. J. C. Arthur from Prof. H. W. Anderson who wrote that he had collected 
it for a Synchytrium but upon examination found what he thought were 
uredinia. An examination of the material showed that Professor Anderson 
6 Rhoads, A. S., Hedgcock, G. G., Bethel, E., and Hartley, C. Host relationships of 
the North American rusts, other than Gymnosporangiums, which attack conifers. 
Phytopath. 8: 309-352. 191 8. 
