CLINTON: NORTH AMERICAN USTILAGINEAE. 
343 
evident and destroying inner and basal parts ; spores lighter colored 
on one side, subspherical to spherical or more rarely more elongated, 
smooth, 5-9 /x, rarely most elongated 11 p. in length. 
Host: Avena sativa, Conn., Ia., Ill., Ivans, (type), Ohio, S. Dak., 
Utah, Wise., W. Ya.; Nova Scotia. 
This smut is very closely related to Ustilago Avenae, also on oats. 
It differs in having smooth spores and does not so thoroughly destroy 
the infested spikelets. As it has usually passed as that species its 
distribution is undoubtedly much more extended than is given here. 
Kellerman and Swingle reported its germination. Literature : 27, 
94, 115. 
Ustilago perennans Rostr. 
Erysibe vera 8 Hold avenacei Wallr., FI. Crypt. Germ., 2 : 217. 1833. 
Ustilago segetum Auct. p. p. 
Ustilago Avenae 1 Auct. p.p. 
Ustilago perennans Rostr., Overs. Kong. Danske Yid. Selsk. Forh., 15. 
Mr. 1890. 
Cintractia avenae Ell. & Tr., Journ. Myc., 6 : 77. My.4890. 
Exsiccati : Ustilago segetum (Bull.), on Arrhenatherum avenaceum , Ell. 
& Ev., N. A. Fungi, 1893 b , Seym. & Earle, Econ. Fungi, 83, Ell. & Ev., 
N. A. Fungi, 2703 ; Ustilago perennans Rostr., on Arrhenatherum avena¬ 
ceum, Seym. & Earle, Econ. Fungi, Clinton Ust. Supp. C 83. 
• 
Sori in spikelets, more or less destroying the basal and inner parts, 
sometimes even running down on pedicles, oblong, about 3-8 mm. 
in length, with dusty, olive brown spore mass ; mycelium perennial 
in perennial parts of host; spores chiefly subspherical or spherical, 
occasionally ovate to ellipsoidal, usually lighter colored on one 
side, more or less minutely echinulate especially on the lighter side, 
5-8 g in length. 
Host: Arrhenatherum avenaceum , Conn., Ia., Ill., Miss, (type C. 
avenae'), Ohio, Vt., Wise. 
This smut is very closely related to Ustilago Avenae and Ustilago 
levis on oats, the infected spikelets resembling those of the latter 
while the spores are more like those of the former. The spores 
average, perhaps, smaller than with those species. The fact that 
the mycelium is perennial has been taken by Rostrup as the chief 
1 Brefeld considers this smut the same as that on oats. 
