DESCRIPTIONS OF TRIBES AND GENERA. 113 



and palea cliartaceous, somewhat indurated, awnless ; 

 spikelets comparatively large. 



Species one, A. arundinacea Host. (" Sand reed"), has 

 long, creeping rhizomes, and cylindrical, false spikes. 

 On the sandy coasts of Europe and the Atlantic States of 

 N. America, rarely in the interior. This grass is fre- 

 quently planted for binding the dunes and loose sands, 

 as it penetrates these by a thick network of rhizomes 

 that withstands the strongest washing of the waves. A 

 cross (A. Baltica Link) is sometimes formed with Cala- 

 magrostis Epigeos Roth. 



Obs. —Very nearly related to Ammophila are two N. American spe- 

 cies, Calamagrostis brevipilis Gray and C. longifolia Hook., with the 

 loose panicle of Calamagrostis, but the chartaceous flowering glumes of 

 Ammopltila, distinct from both genera by the one-nerved flowering 

 glumes ; they may best be considered a separate genus, Calamovilfa 

 (Gray as a sect, of Calamagrostis). (Hackel in MS.) 



[138a. Calamovilfa. Empty glumes unequal ; flower- 

 ing glumes one-nerved ; rachilla not prolonged. 



Species two, in N. America (0. brevipilis of the 

 Atlantic coast, and ft longifolia of the western interior). 

 These species are referred to Ammophila in B. & H. Gen. 

 PL, vol. Ill, p. 1153.] 



139. (138) Apera Adans. (Anemagrostis Trim). Pani- 

 cles loose, spikelets delicate ; rachilla prolonged, naked. 

 Awns four times as long as the flowering glumes, straight 

 or somewhat geniculate. 



Species two, in Europe and Western Asia. A. Spica- 

 Venti Beauv. is often a troublesome weed in crops. [In- 

 troduced into United States about Philadelphia, etc.] 



140. (1-42) Dichelachne Endl. Panicles dense, long 

 and narrow, bristly on account of the numerous awns ; 

 rachilla very slightly produced ; awns very long, some- 

 what flexuous, not bent. 



Species two (D. crinita and D. sciurea Hook.), from 

 Australia to New Zealand. 



141. (143) Trisetaria Forsk. (Anomalotis Steud.). Pani- 

 cles long and narrow ; rachilla prolonged, pedicel-like ; 

 middle awn from the back of the flowering glume, genic- 

 ulate, twisted below ; lateral awns delicate, straight. 



