1922] Wiegand,—East-American Species of Bromus 89 
NOTES ON SOME EAST-AMERICAN SPECIES 
OF BROMUS. 
K. M. WiEGAND. 
Ir one may judge from the confusion of specimens in many herbar- 
ia, the species of Bromus are not yet satisfactorily understood, not- 
withstanding the revision of Shear (Bull. U. S. Div. Agrost. no. 23, 
1900) and the more recent treatments in our various manuals. Per- 
haps the followirig brief sectional keys will aid in making clear the 
relationship of some of the eastern species. 
Following Rouy & Foucaud (Fl. France), Ascherson & Graebner 
(Synop. Mitteleu. Flora) and other authors, Bromus secalinus, B. 
racemosus, B. commutatus, and B. hordaceus may be correlated in 
the following manner: 
a. Lemmas firm; panicle not compact though the branches 
often erect; spikelets plainly pedicelled. b. 
b. Lemmas at maturity spreading, each individually invo- 
lute exposing the rachilla, 7-8 mm. long, all nearly equal, 
sheaths glabrous except the lowermost; blades pubes- 
cent or subglabrous; panicle loose, the branches gener- 
ally more or less spreading; anthers 1.5-1.8 mm. long. c. 
c. Lemmas glabrous....... Ju du E ERE M 1. B. secalinus. 
edu No Sh ace dee ves ee forma hirtus. 
b. Lemmas at maturity ascending, not separately involute, 
therefore the rachilla not ordinarily exposed; lower 
lemmas longer than the upper; panicle contracted, the 
branches erect; sheaths and dos pubescent. c. 
c. Lemmas 7 mm. long; anthers 2.0-2.5 mm. long; panicle 
contracted; branches short, in pairs, bearing 1(2) 
Ëer sured, ey) ery UEM 2. B. racemosus. 
c. Lemmas 9 mm. long; anthers 1.5 mm. long; panicle 
more open, with long lower branches bearing several 
spikelets except in depauperate specimens.........3. B. commutatus. 
a. Lemmas thin, veiny; panicle compact; the branches very 
short and spikelets nearly sessile; (lemmas broader than 
in the last species, 7-9 mm. long; anthers 1-2 mm. long; 
sheaths and blades pubescent). b. 
"TSN 4. B. hordaceus. 
b. Spikelets glabrous or merely scabrous..............forma leptostachys. 
1. B. secatinus L., Sp. Pl. 76 (1753).—Common in grain fields 
and waste places almost throughout the United States and southern 
Canada. 
Forma hirtus (F. Schultz) comb. nov. B. secalinus, var. velutinus 
Rchb. Icon. Fl. Germ. i. t. Ixxv, fig. 1599 (1834), not Schrad. B. mu- 
tabilis ò hirtus F. Schultz, Flora, xxxii. 235 (1849). B. secalinus I. vul- 
garis, a. typicus, 2. hirlus Aschers. & Graeb. Syn. Mitteleu. Fl. ii. 
604 (1901).—One specimen seen from America, collected in an oat- 
