GENERA OF GRASSES OF THE UNITED STATES. 113 
utilized for hay. Much of the grain hay of that region is made from 
either cultivated or wild oats. 
The varieties of cultivated oat are derived from three species of 
Avena. The common varieties of this country and of temperate and 
mountain regions in general are derived from A. fatwa. The 
Algerian oat grown in North Africa and Italy and the red oat of our 
Southern States are‘ derived from A. sterilis. A few varieties 
adapted to dry countries are derived from A. barbata'. 
Avena sterilis L., animated oats, is sometimes cultivated as a 
curiosity. When laid on the hand or other moist surface the fruits 
twist and untwist as they lose or absorb moisture. 
Our two native species, found in the Rocky Mountain region, are 
perennials, with narrow few-flowered panicles of erect spikelets 
smaller than those of Avena sativa. They are excellent forage 
grasses, but occur only scatteredly. 
48. ARRHENATHERUM Beauv. 
Spikelets 2-flowered, the lower floret staminate, the upper perfect, 
the rachilla disarticulating above the glumes, produced beyond the 
florets as a slender bristle; glumes rather broad and papery, the first 
1-nerved, the second a little longer than the first and about as long 
as the spikelet, 3-nerved; lemmas 5-nerved, hairy on the callus, the 
lower bearing near the base a twisted, geniculate, exserted awn, the 
upper bearing a short, straight, slender awn just below the tip. 
Perennial, rather tall grasses, with flat blades and rather dense 
panicles. Species about six, in the temperate regions of Eurasia; 
one species introduced into the United States. 
Type species: Arrhenatherum avenaceum Beauv. 
Arrhenatherum Beauy., Ess. Agrost. 55, pl. 11, f. 5. 1812. Beauvois figures 
one species, which he calls Arrhenatherum avenaceum. This is Avena elatior 
L., and is now called Arrhenatherum elatius (L.) Mert. and Koch. 
Arrhenatherum clatius (Pl. XII; fig. 59) is occasionally cultivated 
in the humid regions of the United States as a meadow grass under 
the name of tall oat-grass. It is a fairly satisfactory forage grass, 
but the seed is expensive and often of poor quality. This species is 
often found growing spontaneously in grassland and along road- 
sides in the Northern States. 
A variety, Arrhenatherum elatius bulbosum (Presl) Koch, has ap- 
peared recently in some of the Atlantic States. It differs from the 
ordinary form in having at the base of the stem a moniliform string 
of 2 to 5 small corms 5 to 10 mm. in diameter. 
1 See Journ. Hered, 5: 56, 1914, a translation of an article by Trabut. Also see Norton, 
Amer. Breed. Assoc. 3: 281. 1907. 
97769°—19—Bull. 772-——-8 
