150 Bulletin 313 



Rhizoctonia solani Kiihn. — Ver>' common on potatoes, tomatoes 

 and carnations. Also reported on asparagus, alfalfa, horse-radish 

 and many other plants. The cause of some very severe root and 

 stem rots. Mycelium tufted, brown, closely septate, constricted at 

 septa, frequently branching almost at right angles becoming yellow 

 with age. Sclerotia variable in size, soft, white, becoming brown to 

 black, composed of irregular and barrel-shaped cells. Sclerotia 

 break into small masses whose cells function as chlamydospores. 



864. Infected root of alfalfa. 865. Infected root or horse-radish. 866. My- 

 celium and cell formation from potato, 1/12. 867. Same from potato, 1/6. 

 868. Same from asparagus, 1/12. 



UsTiLAGO anomala J. Kunze. — On irdorescence of Polygonum 

 cilinode. "Sori in ovaries or essential organs, the infected parts 

 often remaining distinct, 2-3 mm. in length, protected by the peri- 

 anth, forming a dusty purplish spore-mass, spores light violet, chiefly 

 ovoid to spherical or occasionally somewhat irregular, with rather 

 fine reticulations (chiefly 1-3 fi wide by 1 /i, deep), 10-15 jx, rarely 

 17 IX in length." North American Flora, v. 7, p. 22 (1906). 



869. Infected inflorescence of P. cilinode. 870. Spores, 1/12. 



UsTiLAGO AVEN^ (Pers.) Jens. — On inflorescence of cultivated 

 oats. "Sori in spikelets, forming a dusty olive-brown spore mass, 

 about 6-12 mm. long by half as wide, usually rather completely de- 

 stroying the floral parts, eventually becoming dissipated, rarely in 

 leaves; spores lighter-colored on one side, subspherical though often 

 more elongate, minutely echinulate, 5-9 ^ in length." North Ameri- 

 can Flora, V. 7, p. 7 (1906). 



871. Infected oat plant. 872. Spores, 1/12. 873. Basidiospore, 1/12. 874. 

 Germinating spores, 1/12. 



UsTiLAGO HEUFLERi Fcl. — On the leaves of Erythronium ameri- 

 cannm. "Sori in leaves, forming conspicuous rounded or often 

 elongate pustules, covered by a thin whitish membrane which upon 

 rupture discloses a somewhat dusty black spore-mass ; spores dark 

 reddish-brown, ovoid or ovate to spherical, usually regular thick- 

 walled, smooth but inner wall provided with more or less evident 

 projections extending into outer lighter-colored part, 13-22 ,ti in 

 length." North American Flora, v. 7, p. 20 (1906). 



875. Infected leaf cf E. americanum- 876. Spores, 1/12. 



UsTiLAGO HORDEi (Pers.) K. & S. — On inflorescence of cultivated 

 barley. "Sori in spikelets, forming an adhering purple-black spore- 



