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2 ⁵ AS QNM A MED C MC A er 
s 
STUDIES ON AMERICAN GRASSES. 
I. THE GENUS IXOPHORUS. 
By F. LAMSON-SCRIBNER. 
Thirty-four years ago Schlechtendal, in a paper on Setaria Beauv., 
published in the thirty-first volume of Linnæa what he stated might at 
pleasure be regarded a section of Panicum or a distinct genus, naming- 
it Ixophorus. This genus (or section) was established upon a grass col- 
lected by Schiede in December, 1834, at Atlacomulco, Mexico, and the 
Urochloa uniseta of Presl (Reliq. Haenk., 319, 1830), of which he only 
had a fragmentary specimen. Little was known of these grasses by 
other European botanists, and Bentham, who had never seen them, 
referred Irophorus to Setaria, and in this he was followed by Hackel. 
The grasses placed in Lrophorus by Sehleehtendal were apparently over- 
looked by collectors for many years, no speeimens having been found 
until 1886, when Dr. E. Palmer collected what is evidently Presl's 
Urochloa uniseta, at Tequila, in the State of Jalisco (Palmer, No. 372), 
and three years later another species was discovered by Mr. C. G. 
Pringle in the valley of the Rio Grande de Santiago (No. 2423, Pringle, 
1889). The same form as that collected by Pringle was, in 1891, collected 
by Dr. Palmer at Colima (No. 1256). Through the kindness of Dr. 
Trelease, I have been enabled to examine a typical specimen of Presl’s 
species eontained in the Bernhardi collection in the herbarium of the 
Missouri Botanical Garden. The specimens collected by Palmer in 1886 
are identical with Urochloa uniseta Presl, and a study of the material 
now in hand has led me to believe that the special characters which 
these grasses present are of generic Tnm and that Ixophorus is a well- 
established genus. 
A REVISION OF THE SPECIES. 
Ixophorus "X Linnwa, XXXI, 420 (1861 and 1862). Spikelets with one ter- 
rmaphrodite or female flower, with a larger male one below it, very 
short Webibsilins, imbrieate and uniseriate along the branches of a simple pani- 
cle, the pedicels, as well as the main axis and primary branches, produced beyond 
the spikelets into slender smooth and viscid awn-like bristles, which equal or 
exceed the spikelets in length. Glumes, 4, the first very short and 3-nerved, 
the second a little shorter than the third and many-nerved, the third 5-nerved |. 
and much exceeding the punctate-scabrous, 5-nerved, fertile glume, which is i 
flattened and bisuleate on the back, with a distinet hippocrateriform — ; 
