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 genus, 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.) Sceribn., 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. Acrostis L., the bent-grasses. 
Spikelets 1-flowered, 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 1. 
Agrostis L., Sp. Pl. 61, 1753; Gen. Pl., ed. 5, 30. 1754. Linneus 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,’ it must be chosen from the first group, Aristatae, and from those 
* See American Code of Botanical Nomenclature, Bull. Torrey Club 34:174. 1907. ‘The 
statement is made that “the genera of Linnmwus’s Species Plantarum (1753) are to be 
typified through the citations given in his Genera Plantarum (1754).” There is no 
citation given for Agrostis and the code does 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. 
