340 
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Vol. II, No. 5 
sorgo (Failyer and Willard, 1890, p. 145), which would suggest Africa 
as its source. 
There appear to be three distinct forms of smut (PI. XXXII, fig. 1) 
affecting the sorghum crop in America (Potter, 1912 ): Sphacelotheca 
cruenta (Kuhn), Sphacelotheca sorghi (Link) Clint., and Sorosporium 
reUianum (Kuhn) McAlp., the head smut (PI. XXXII, fig 2). Of these 
the last-named alone has consistently resisted efforts to prevent its 
spread, though all known methods for the prevention of cereal smuts 
have been tried. The serious occurrence of the disease has been observed 
to be confined at present to the Texas Panhandle. For this reason the 
investigations, begun in 1907 by Dr. E. M. Freeman and continued after 
1909 by the writer, 1 have been carried out chiefly at Amarillo, Tex., with 
plantings at other points for comparison. This work has been supple¬ 
mented by studies in the greenhouse and laboratory at Washington, D. C* 
SYNONYMY 
The head smut of sorghum was first noted by Julius Kuhn (1875), who 
described it from a specimen sent to him from Egypt by Dr. Reil in 1868. 2 3 
The mistake he made in describing the spores as smooth was repeated by 
Passerini (1876) when he described the form of maize. The echinula- 
tions are often obscure, however, unless the spores are quite mature and 
dry. Brefeld (1883, p. 94) describes them as almost smooth. 
Saccardo (1876) and de Toni (1888) described this smut as showing an 
aggregation of spores suggestive of Sorosporium, as did also Norton (1896, 
p. 233). Busse (1904, p. 381) suggests in this connection, as Brefeld 
(1883, p. 171) did earlier, that possibly the genus Sorosporium should not 
be retained. Busse notes and figures the characteristic spore aggregates, 
but states that this smut is intermediate in this respect between Ustilago 
and Sorosporium. According to Dietel (1900, p. 7), the two genera are 
not sharply distinguishable. Although the spores are rather loosely 
bound together in this species, McAlpine (1910a, p. 181) has recently 
placed it in the genus Sorosporium. Under the present artificial system 
necessitated by a lack of adequate knowledge of the natural relationships 
1 The author wishes to acknowledge the advice and assistance of Mr. E. C, Johnson, who was in charge 
of the cereal-disease work from 1908 to 19x2, inclusive, during which time most of the work here presented 
was done. Considerable assistance has also been given by various officials at the stations where the work 
was performed, among whom Dr. E. M. Freeman should be especially mentioned. 
3 “ Ustilago Reiliana Kuhn in litt. U. sporis laevibus, subglobosis, crassiusculis (10, 4 Mikr. inter et 13, 
3 Mikr. diamet. variantib.) semipellucidis, brunneis; paniculam totam contractam et obvolutam et abor- 
tivam corrumpens. Crescit in Sorgho vulgari.” Rabenhorst's Fungi Europaei Exsiccati, No. 1998. 
The name given by Kuhn is still retained by European mycologists. Its synonymy follows: 
Ustilago reiliana Kuhn, 1875, in Rabenh., Fungi Europ. Exs., ed. nova, s. 2, cent. 20, no. 1998. 
Ustilago reiliana, forma zeae , Pass., 1876, in Rabenh., Fungi Europ. Exs., ed. nova, s. 2, cent. 1 (resp. cent. 
21), no. 2096. 
Ustilago pulveracea Cooke, 1876, in Grevillea, v. 4, no. 31, p. 115, pi. 63. 
Cintractia reiliana Clint., 1900, Ill. Agr. Exp. Sta. Bui. 57, p. 346. 
Ustilago ( Cintractia) reiliana forma foliicola Kellerm., 1900, in Ohio Nat., v. 1, no. 1, p. 9, pi. 2. 
Sphacelotheca reiliana Clint., 1902, in Jour. Mycol., v. 8, no. 63, p. 141. 
Sorosporium reiltanum McAlp., 1910, Smuts of Austral., p. 181. 
