Studies in North American Peronosporales — III. New or noteworthy 



species" 



Guy West Wilson 



Albugo Trianthemae sp. nov. 



» 



Soris hypophyllis, rotundis vel irregularibus, rarius confluen- 

 tibus, immersis, promentibusque, subflavidis, i-io mm. latis, con- 

 idiophoris cylindraceis, circa 10 x 60 p ; conidiis subflavidis, brevi- 

 ter cylindraceis, circa 8-IO ft x 8-IO /i, terminalibus majoribus, 

 circa 9—1 1 ft x 12-14 /A membrana hyalina, ad medium annulo 

 cincta ; oosporis in foliis hospitis, globosis, 60-80 ft diametro, epi- 

 sporis brunneis, regulariter vel irregulariter reticulatis, areolis circa 

 4 {i latis. 



Sori hypophyllous, rounded or irregular in outline, rarely con- 

 fluent, rather deep-seated, prominent, yellowish, 1-10 mm. ; con- 

 idiophores cylindric, about 10 x 60 ft; conidia short-cylindric, 8- 

 10 p X 8-10 ft, the terminal larger, 9-1 1 ft x 12-14 ft, membrane 

 hyaline, with an equatorial thickening, contents light yellow, 

 oospores produced in the leaves of the host with the conidia, glob- 

 ular, 60-80 ft, averaging about 70 ft, epispore dark brown, rather 



closely and shallowly reticulate, areolae regular or irregular, 

 about 4 fx. 



Type in herb. Wilson, and duplicates of the same collection 

 m herb. Underwood and the herbarium of the New York Botan- 

 lcal Ga *"den. Collected by E. O. Wooton near Las Cruces, New 

 * Ie *ico, on Trianthcma Portidacastrum L. 



This species stands between Albugo occidentalis and A. platen- 



sts > being distinguished from the former by its larger conidia, 

 *Wch are lighter in color and dissimilar in size, and by its larger 

 a darker oospore, which is less regularly and more deeply retic- 

 le ate ! and from the latter by its cylindric conidia with the mem- 

 rane SJ milarly colored throughout, and by its larger and less deeply 

 reticulate o6spore. The conidia are also quite similar to those of 

 • Tr «gopogonis but the oospores are not tuberculate. The host 

 ggests an affinity with A. Portulacae, but the annulate, dissimi- 

 *!" Conidia and the absence of the tubercles in the areolae of the 

 °2>ore preclude such a relationship. 



JL *"\ , 



resented before Section G, A. A. A. S., «t Chicago, Dec. 31, 1907, as " New 

 ""Worthy Peronosporales." 



361 



