GRASSES OF IOWA. 



329 



SI 



General. Wheat is widely cultivated in temperate regions of the 

 old and new worlds. Cultivated in Europe in prehistoric times. Its 

 original home is western Asia. 



5. HORDEUM. 



Hordeum L. Sp. PI. 84. 1753. Endlicher. Gen. PI. 104. Bentham and 

 Hooker. Gen. PI. 3: 1206. Scribner. Bull. U. S.Dept. Agrl. Div. Agros. 

 20: 165. /. 133. 



Critho E. Mey. Ind. Hort. Region. 1848. 



Zeocriton Beauv. Agrost. 114. 1812. 



Critesion Raf. Jour. Phys. 89: 103. 1819. 



Spikelets one-flowered, with an awl-shaped rudiment on the inner 

 _.de, three at each joint of the rachis of a terminal spike. The lateral 

 ones usually imperfect or abortive, and short-stalked. Empty glumes 

 side by side, in front of the spikelets, six in number, forming a kind of 

 involucre, slender and awn-pointed, or bristle-form. Flowering glume 

 and palet herbaceous, the former (anterior) convex, long-awned from 

 the apex. Stamens .3. Grain oblong, commonly adherent. Spike often 

 separating into joints. Ours annuals or biennials, or scarcely perennial. 

 (The ancient Latin name.) 



Hackel recognizes sitxeen species of Hordeum, although Bentham 

 & Hooker only give twelve. The species occurs in temperate Asia, 

 Europe, Africa and North and South America; of the sixteen species Beal 

 records eight for the United States ; but Scribner and Smith 1 record ten 

 species in 1897. Several species have been added since then; it is prob- 

 able, however, that the number of species will be somewhat reduced. 



KEY TO THE SPECIE3 OF HORDEUM. 



A. Lateral spikelets sessile (cultivated species). 



1 Flowers in the lateral spikelets sterile, making the fruiting spike 



appear distichous H. distichon.K 



2 Flowers in the lateral spikelets fertile, the fruiting spike appear- 



ing six-rowed H- vulgare". 



B. Lateral spikelets raised on a short pedicel. 



1. Empty glumes all alike, subulate. 



a. Floret of the lateral spikelets rudimentary, awniess, or short- 

 awned. 



(1) Awn of the flowering glume in the central spikelet 2.5-6 



mm. long H - fudatum. 1 . 



(2) Awn of the flowering glume of the central spikelet less 



than 1.5 cm. long H. nodosum.*. 



b Flower of the very short-pedicelled, lateral spikelets fertile; awn 

 about 2 cm. long H. Pammeli*. 



2. Empty glumes of the middle spikelets, and the inner empty.glumes 



of the lateral spikelets dilated above the base.. H. pusillum. 9 . 



