GENERA OF GRASSES OF THE UNITED STATES. 125 



graph quoted from Hackel ("Hackel in MS.") is a statement that two species, 

 Calamagrostis brevipilis Gray and C. longifolia Hook., may best be considered a 

 separate g3iius, Calamovilfa. Scribner adds a note formally describing the genus 

 Calamovilfa and mentions the two species, Calamovilfa brevipilis and C. longi- 

 folia. The first is selected as the type. 



The genus differs from Calamagrostis in the chartaceous lemma, 

 from our species of Calamagrostis in the absence of a prolonged ra- 

 chilla, and from Ammophila in the more open panicles and in the 

 absence of the prolongation of the rachilla. 



The four species are Calamovilfa brevipilis (Torr.) Scribn., in the 

 pine barrens from New Jersey to North Carolina; C. curtissii 

 (Vasey) Scribn., confined to Florida; C. longifolia (Hook.) Scribn. 

 (fig. 66), of the Great Plains and the dune region of Lake 

 Michigan; C. gigantea (Nutt.) Scribn. and Merr., also of the 

 Great Plains. The first two species are without creeping rhizomes; 

 the other two have numerous stout rhizomes and are excellent sand 

 binders. Calamovilfa longifolia and C. gigantea are closely re- 

 lated. They are differentiated by the less expanded panicle and 

 glabrous florets of the first and the spreading panicle, larger spike- 

 lets, and villous florets of the second. 



Calamovilfa longifolia, the commonest species, is of some value for 

 forage, but is rather coarse and woody. 



56. AGBOSTIS L., the bent-grasses. 



Spikelets 1-flowerecl, disarticulating above the glumes, the rachilla 

 usually not prolonged; glumes equal or nearly so, acute, acuminate, 

 or sometimes awn-pointed, carinate, usually scabrous on the keel and 

 sometimes on the back; lemma obtuse, usually shorter and thinner in 

 texture than the glumes, awnless or dorsally awned, often hairy on 

 the callus; palea usually shorter than the lemma, 2-nerved in only 

 a few species, usually small and nerveless or obsolete. 



Annual or usually perennial, delicate or moderately tall grasses, 

 with glabrous culms, flat or sometimes involute, scabrous blades, and 

 open or contracted panicles of small spikelets. Species about 100, 

 in the temperate and cold regions of the world, especially in the 

 Northern Hemisphere. About 25 species are found in the United 

 States, some of these being found also in Europe. 



Type species : Agrostis stolonifera L. 



Agrostis L., Sp. PI. 61, 1753; Gen. PI., ed. 5, 30. 1754. Linnaeus describes 

 12 species, dividing them into two groups, Aristatae and Muticae. The descrip- 

 tion of the genus refers to the lemma as being awned and to the presence of 

 a palea ("Cor. bivalvis . . . altera majore aristata"). If the type species 

 must agree with the description in the fifth edition of the Genera Plan- 

 tarum, 1 it must be chosen from the first group, Aristatae, and from those 



1 See American Code of Botanical Nomenclature, Bull. Torrey Club 84 : 174. 1907. The 

 statement is made that "the genera of Linnseus's Species riantarum (1753) are to be 

 typified through the citations given in his Genera Plantarum (1754)." There is no 

 citation given for Agrostis and the code docs not definitely require that the genera must 

 be interpreted by the descriptions here given ; hence the type species may be chosen inde- 

 pendent of this description. 



