328 
Mycologia 
103. Uredo capituliformis P. Henn. Hedwigia 34: 97. 1895. 
Ravenelia capituliformis P. Henn. Hedwigia 43 : 160. 1904. 
On Euphorbiaceae : 
Alchornea latifolia Sw., Luguillo forest, Dec. 2, 5437 \ 
Preston’s ranch near Naguabo, Dec. 31, dddp. 
This is the first record of the occurrence of this species in 
North America. The type collection was made by E. Ule 3060, 
at Goyaz, Brazil, and shows an abundance of the very peculiar 
uredinial sori. These sori arise from under the cuticle from a 
minute hymenial layer. They expand into a globular, brown 
capitulum, seated lightly on the surface of the leaf and composed 
of incurved, thick-walled, dark-brown paraphyses, holding a 
small number of spores. The appearance under a low magnify- 
ing power is much like that of the fruit of some Erisyphe or 
other Perisporiaceous fungus. The spores are equally remark- 
able with the sori in possessing four bulging protuberances in the 
upper half of the generally obovoid spore, and a similar apical 
protuberance. The wall of the spore is cinnamon-brown, 1-1.5/1 
thick, and closely echinulate. The pores can not be located. 
In these characters the rust collected by Stevens in Porto Rico 
agrees perfectly. In addition, however, both the Stevens’ col- 
lections show well formed pycnia and aecia. The pycnia are 
conspicuous, epiphyllous, in small groups, mamilliform, sub- 
cuticular but depressing or absorbing the epidermal cells, 100- 
165 /A across; ostiolar filaments apparently wanting. The aecia 
are amphigenous, gregarious, more abundant on the upper surface 
of the leaf surrounding the pycnia. They are subepidermal, 
with the adjoining epidermal cells greatly elongated to form a 
cone about the mouth of the aecium. A persistent peridium 
barely protrudes beyond the leaf-surface, and the structure can 
not be determined with dried material. The aeciospores are 
catenulate with intercallary cells. They closely resemble the re- 
markable urediniospores in form, color and markings, but the 
echinulation, if such it is to be calkd, is considerably coarser. 
The finest points appear like those on the urediniospores. The 
points are, however, mostly conspicuously hyaline, acute warts, 
although their bases are too narrow for them to be unreservedly 
called verrucose. 
