FLORA OF NEW MEXICO, 91 
WOOTON AND STANDLEY 
58. TRIDENS Roem. & Schult. 
Perennials with flat or involute leaves and open or contracted, sometimes spike- 
like inflorescence; spikelets 3 to many-flowered, the flowers perfect or the upper 
staminate; glumes keeled, obtuse to acuminate, usually shorter than the lemma; 
lemmas 3-nerved, the midnerve or all the nerves excurrent, pilose, the apex entire 
or shortly 2-toothed; palea compressed, 2-keeled; stamens 3; styles short, distinct. 
KEY TO THE SPECIES. 
Lemmas not pilose on the back; glumes considerably surpassing 
the lower florets; spikelets subcompressed, oblong, in a 
rather dense spikelike panicle. . we eeeeeeee -. Ll. T. albescens, 
Lemmas pilose on the back, at least at. ‘the base; elumes barely as 
long as the lowest florets, or shorter; spikelets various. 
Spikelets terete; sterile lemma not ciliate, neither lobed nor 
awned...........02.0 0220 e eee eee eee eee ee eee eee 2. T. muticus. 
Spikelets compressed; sterile lemma ciliate, deeply bilobate, 
with an intermediate awn. 
Lemmas only slightly cleft at the apex, the lobes narrow, 
acute; spikelets 10 mm. long.................---- 
Lemmas cleft half their length, the lobes obtuse; spike- 
lets 6 to8 mm. long.............-.-.-.-.--2.---- 
Tridens albescens (Vasey) Woot. & Standl. N. Mex. Agr. Exp. Sta. Bull. 81: 
129. 1912. 
Triodia albescens Vasey, U. S. Dept. Agr. Div. Agrost. Bull. 127: 33. 1891. 
Sieglingia albescens Kuntze; L. H. Dewey, Contr. U.S. Nat. Herb. 2: 538. 1894. 
Rhombolytrum albescens Nash in Britton, Man. 129. 1901. 
Type Locauity: ‘‘Texas and New Mexico.”’ 
Rance: Kansas to Texas and eastern New Mexico. 
New Mexico: Mesilla Valley; Carlsbad; Roswell. 
Upper Sonoran zones. 
2. Tridens muticus (Torr.) Nash in Small, Fl. Southeast. U. 8. 143. 1903. 
Tricuspis mutica Torr. U. S. Rep. Expl. Miss. Pacif. 4: 156. 1856. 
Triodia mutica Benth.; S. Wats. Proc. Amer. Acad. 18: 180. 1883. 
Type Locatiry: Laguna Colorado, New Mexico. 
Rance: Western Texas and eastern New Mexico. 
New Mexico: Socorro; Laguna Colorado; Cross L Ranch; Tortugas Mountain; 
Roswell. Dry hills, in the Lower and Upper Sonoran zones. 
3. Tridens avenaceus (H. B. K.) Hitche. Contr. U. 8. Nat. Herb. 17: 357. 1913. 
Triodia avenacea H, B. K. Nov. Gen. & Sp. 1: 156. pl. 48. 1816. 
Triodia grandiflora Vasey, Contr. U. S. Nat. Herb. 1: 59. 1890. 
Sieglingia avenacea grandiflora L. H. Dewey, Contr. U. 8. Nat. Herb. 2: 538. 1894. 
Tridens grandiflorus Woot. & Stand]. N. Mex. Agr. Exp. Sta. Bull. 81: 129. 
1912. 
Type Locauity: ‘‘In convalle Mexicana inter montem Chapultepec et Penol de 
3. T. avenaceus. 
4. T. nealleyt. 
Dry plains, in the Lower and 
los Banos.”’ 
Rance: Western Texas to Arizona and southward. 
New Mexico: Kingston ( Metcalfe 1334). 
/ 4. Tridens nealleyi (Vasey) Woot. & Standl. N. Mex. Agr. Exp. Sta. Bull. 81: 
129. 1912. 
Triodia nealleyi Vasey, Bull. Torrey Club 15: 49. 1888. 
Sieglingia nealleyi L. H. Dewey, Contr. U.S. Nat. Herb. 2: 538. 1894. 
Type LOCALITY: Western Texas. 
