456 
Journal of Agricultural Research 
Vol. XXIII, No. 
Summarizing the evidence at hand, bunt appears to be a highly special¬ 
ized parasite, consisting of but a single biologic race and existing on but 
a single host genus, Triticum. 5 Its spores are disseminated both on the 
seed of the host and by wind to fields of fall wheat. Infection takes 
place only during the seedling stage of the host and to be effective may 
require multiple infection. It produces but one crop of spores a year, 
these being deposited in the wheat ovaries following the flowering period. 
Next to rust, it is the most destructive parasite of wheat. Besides the 
actual loss due to bunted heads, additional losses occur through feeding 
smutty grain to animals, through lowering the vitality of the seed by 
treatment with disinfectants, through the time and expense of treating 
the seed, through fires caused by explosions of spores during thrashing, 
through extra cleaning required in milling, and through experiments of 
farmers, such as planting out of season, changing seed, and trying other 
unadapted plants in an effort to avoid a smutty crop. 
the; host 
There are eight commonly recognized species of wheat in American 
agricultural literature. According to Tschermak (57) Einkom, Triticum 
monococcum is quite distinct from the others and generally will not cross 
with them, although Blaringhem (5) succeeded in crossing it with durum 
and Polish wheat. Emmer, T. dicoccum Schr., is thought to be the 
progenitor of the other six. Durum, T. durum Desf., Polish, T. polonicum 
L., and Poulard, T. turgidum L. are inter-fertile but show about 50 per 
cent sterility when crossed with the other three. Common wheat, T. 
vulgare Vill., Club wheat, T. compactum Host., and Spelt, T. spelta L. are 
all fertile inter se. 
Triticum generally shows intersterility with other genera, although 
crosses have been made with Secale (rye), but the F x generation is nearly 
always sterile, rarely producing seed. Love and Craig (27) reviewed 
former work on wheat-rye hydrids and reported a cross between Dawson 
Golden Chaff and common rye in which they obtained a single plant in 
the F 1? F 2 , and F 3 generation, there being but one seed produced in each 
of the first two generations. The F 3 generation was not so nearly sterile, 
for it produced a number of seeds from which a variable population of 
F 4 segregates were obtained. 
In common with many other members of the grass family the bread 
wheats have hollow stems closed at the nodes and two-ranked parallel- 
veined leaves consisting of sheath and blade. The sheath envelopes the 
stem with the edges overlapping. The flowers are perfect, arranged 1 to 6 
on a spikelet, and the spikelets alternate on the rachis to form a spike. 
Two empty glumes inclose each spikelet. Each flower is inclosed in a 
floral glume on the outside and a palea on the inside and consists of 
three stamens with slender filaments and a 1-celled ovary beneath two 
styles with plumose stigmas. Wheat generally is self-fertilized, but 
natural hybrids sometimes occur in arid climates. 
After germination the plant passes through a vegetative stage in which 
it produces a cluster of leaves (the stool), tillering from a zone of active 
5 Since completing this manuscript I found two smutted ryelike plants in an F2 generation of Hybrid 
128 wheat Rosen rye. The characteristic odor and reticulated surfaces of the spores make it almost certain 
that the casual organism was Telletia trilici, (Bjerk.), Wint. The same season (1921) F. J. Stevenson found 
two heads of what looked like bunt on common rye in our cereal nursery at Pullman, Wash., near the 
place where the two rye-wheat hybrid plants had been found. 
