O’GaRA : COLLETOTRICHUM AND PhOMA 
41 
A New Species of Phoma on Asclepias 
Upon examining some mycological collections made by W. W. 
Jones of this department during the past season in the Salt Lake 
Valley, Utah, I found an interesting Phoma on the stems and 
foliage of Asclepias speciosa Torr. The examination of many 
specimens showed that in every instance it was associated with 
Cercospora clavata (Ger.) Peck. The leaf and stem spots always 
showed the presence of both the Phoma and Cercospora. In 
some cases definite areas of the spots were covered by both spe- 
cies, but often the pycnidia of the Phoma and the acervuli of the 
Cercospora are intermingled. Where definite areas of the spots 
are covered by the two species, it is easy to recognize one from 
the other by noting the lighter-colored brown areas of the Cer- 
cospora as contrasted with the dark-brown or black-colored areas 
occupied by the Phoma. Carefully prepared microtome sections 
show the intermingling of the mycelium of both species. In the 
Phoma leaf-spots, practically the entire structure between the 
upper and lower epidermis is destroyed, and the space occupied 
by the light-brown mycelium. Pycnidia are often distinctly 
beaked. The description of this species is as follows ; 
Phoma rostrata sp. nov. 
Mactilis in caulibus lenticulatis vel elongatis ; in foliis amphi- 
genis irregularibus, nervulis limitatis, atro-brunneis vel nigris; 
peritheciis sparsis vel dense gregariis, brunneis vel atro-brunneis, 
semi-immersis, globosis, prominulis vel rostratis, 56-95 diam. ; 
mycelio in cellulis hospitis brunneo, ramoso, pluriseptato, hyphis 
circa 3/t dam.-, spot iilis i. 4-2. 3 X 4-6 /a, eguttulatis, oblongis, 
utrinque rotundatis, plerumciue leniter curvulatis ; basidiis non 
vivis. 
Hab. in foliis et caulibus vivis et languidis Asclepiadis specio- 
sae^ cum Cercospora clavata in eisdem maculis sociata, Salt Lake 
Valley, Utah, Amer. bor. 
Laboratory of Plant Pathology, 
Department of Agricultural Investigations, 
American Smelting & Refining Company, 
Salt Lake City, Utah. 
