GEAMINEAE (GRASS FAMILY) 



167 



187. A. biflorum. 

 Splkelet x3. 



high ; leaves often lax, 2-5 mm. wide ; spike dense, 5-10 cm. 

 long, usually tinged with purple ; glumes conspicuously 5-7- 

 iierved, the margins thin and widened above the middle, rather 

 abruptly narrowed into a short awn ; lemma 8-10 mm. long, 

 glabrous or nearly so, terminating in an awn shorter than itself. 

 (.4. violaceuin Lange.) — Alpine regions of the 

 Wliite Mts., L. Superior, northw. and westw. 

 June-Sept. (Eu.) Fig. 187. 



6. A. tfinerum Vasey. Culms erect, 5-10 dm. 

 high, rigid ; leaves subrigid, narrow, flat or invo- 

 lute in drying ; spike usually almost cylindrical, 

 green or straw-color, 1-1.5 dm. long; glumes 

 firm, nearly as long as the spikelet, the scarious 

 margin narrow, tapering more gradually into the 

 awned point ; lemma short-awned. — Nfd. to Pa. 

 and Minn., and common in the far West. July, Aug. — The 

 typical form has slender spikes with rather distant spikelets, 

 which are nearly inclosed in the glumes ; this is common westw. 

 and extends into Minn. ; also introduced on the 

 coast of Mass. {Eaton.) Fig. 188. Passing into 

 a form with stouter and denser spikes and broader 

 less rigid leaves which extends eastw. to Nfd. and 

 N. E. ; this is A. novae-angliae Scribn. and essen- 

 tially A. pseudorepens Scribn. & J. G. Sm. 



7. A. caninum (L.) Beauv. (Awnkd Wheat Gra.ss.) Culms 

 erect, 3-10 dm. high ; leaves flat, rather lax, 8-20 cm. long, 2-6 

 mm. wide, scabrous ; spike more or less nodding, at least in fruit, 

 rather dense, 7-15 cm. long; spikelets 1.2-1.5 cm. long exclud- 

 ing the awns ; glumes pointed or awned ; lemmas 3-5-nerved ; 

 awns straight or somewhat spreading, fully twice the length of 

 the lemma. — Sparingly naturalized in cultivated grounds and 

 meadows ; indigenous along our nortnern borders, and westw. 

 July-Sept. (Eu.) Fig. 189. 



8. A. Richardsbnii Schrad. Similar to the preceding ; culms 

 usually taller and stouter ; spike larger, as much as 2 dm. long, 

 erect, l-sided ^spikelets 2 cm. long, excluding the awns, which 

 are often as much as 3-4 cm. long. — Prairies and shores, e. Que. ; Minn., la., 

 and northwestw. June-Sept. 



188. A. tenerum. 



189. A. caninum. 

 Spikelet X 1%. 



80. h6rDEUM [Tourn.] L. Bahlet 



Spikelets 1 (rarely 2)-flowered, 3 together in our species at each joint of the 

 flattened articulate rhachis, the middle one sessile, perfect, the 

 lateral pair usually pediceled, often reduced to awns and 

 together with the glumes of the perfect spikelet simulating 

 a bristly involucre at each joint of the rhachis ; rhachilla 

 prolonged behind the palea as an awn, sometimes with a 

 rudimentary floret ; glumes equal, rigid, narrow-lanceolate, 

 subulate or setaceous, placed at the sides of the dorsally com- 

 pressed floret which is turned with the back of the palea 

 against the rhachis of the spike ; lemma obscurely 5-nerved, 

 tapering into an awn ; palea slightly shorter, the 2 strong 

 nerves near the margin ; grain haii-y at the summit, usually 

 adherent to the palea at maturity. — Caespitose annuals or 

 perennials with terminal spikes which disarticulate at matu- 

 rity, the joints falling with the spikelets attached. (The 

 ancient Latin name.) 



1. H. jubStum L. (Squikrel-tail Grass). Biennials, 

 3-7 dm. high, erect or geniculate at base ; leaves 5 mm. wide 

 or lesg, scabrous ; spike noddinci, 5-12 cm. lon^, (tbout (?§ 



190. H. jubatuin. 

 Three spilcelets xl. 

 Middle, fertile spike 



let X 1%- 



