218 



MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



cleistogenes remaining within the sheaths. Type species, Triplasis americana. 

 Name from Greek triplasios, triple, alluding to the awn and the two subulate 

 lobes of the lemma. The species are of no importance except as they tend to 

 hold sandy soil. 



Lobes of lemma not subulate-pointed; awn shorter than the lemma; annual. 



1. T. PURPUREA. 



Lobes of lemma subulate-pointed; awn longer than the lemma; perennial. 



2. T. AMERICANA. 



1. Triplasis purpurea (Walt.) 



Chapm. Purple sandgrass. (Fig. 

 292.) Annual, often purple; culms 

 ascending to widely spreading, pubes- 

 cent at the several to many nodes, 

 30 to 100 cm. tall, rarely taller; 

 blades flat or loosely involute, 1 to 3 

 mm. wide, mostly 4 to 8 cm. long; 

 panicle 3 to 5 cm. long, with few 

 spreading few-flowered branches, the 

 axillary more or less enclosed in the 

 sheaths; spikelets short-pediceled, 2- 

 to 4-flowered, 6 to 8 mm. long; lem- 

 mas 3 to 4 mm. long, the lobes broad, 

 rounded or truncate, the nerves and 

 callus densely short-villous, the awn 

 about as long as the lobes or some- 

 what exceeding them; palea con- 

 spicuously silky-villous on the upper 

 half of the keels; grain 'about 2 mm. 

 long. — Dry sand, Ontario, 

 Maine, and New Hampshire to 

 Minnesota and Nebraska, south to 

 Florida and Texas; Colorado (intro- 

 duced?); Honduras. In autumnal 

 culms the numerous short joints with 

 sheaths swollen at the base, con- 

 taining cleistogenes, are conspicuous. 

 Plants with awns exceeding the lobes 

 of the lemma have been differentiated 

 as T. intermedia Nash. 



2. Triplasis americana Beauv. (Fig. 

 293.) Perennial; culms slender, tufted, 

 mostly erect, 30 to 60 cm. tall; blades 

 flat or subinvolute, mostly 15 to 18 

 cm. long; panicle 2 to 5 cm. long, the 

 few slender ascending branches with 

 1 or 2 spikelets; spikelets mostly 2- 

 or 3-flowered, about 1 cm. long; lem- 

 mas 5 to 6 mm. long, the lobes about 

 half as long as the entire lemma, sub- 

 ulate-pointed, the nerves with a nar- 

 row stripe of silky hairs, the awn 5 

 to 8 mm. long, pubescent below; 

 keels of the palea long-villous, the 

 hairs erect. % — Dry sand, Coast- 



al Plain, North Carolina to Florida 

 and Mississippi. 



35. NEOSTAPFIA Davy 



(Included in Anthochloa Nees in Manual, 

 ed. 1) 



Spikelets few-flowered, subsessile, 

 closely imbricate around a simple 

 axis, the rachilla disarticulating be- 

 tween the florets; glumes wanting; 

 lemmas flabellate, prominently many- 

 nerved; palea much narrower and a 

 little shorter than the lemma, obtuse, 

 hyaline. Low annual with loose 

 sheaths merging into rather broad 

 flat blades without definite junction 

 and dense cylindric panicles, the axis 

 prolonged beyond the spikelets, this 

 portion naked or bearing small bracts. 

 Type species, Neostapfia colusana. 

 Named for Otto Stapf. (Distinguished 

 from Anthochloa Nees, of the Andes, 

 in which the axis is not prolonged, 

 the short-pediceled spikelets have 

 well-developed persistent glumes, the 

 lemmas are not strongly nerved, and 

 the sheaths and blades are distinctly 

 differentiated.) 



1. Neostapfia colusana (Davy) 

 Davy. (Fig. 294.) Culms 7 to 30 cm. 

 long, ascending from a decumbent 

 base; leaves overlapping, loosely fold- 

 ed around the culm, 5 to 10 cm. 

 long, 6 to 12 mm. wide at the middle, 

 tapering toward both ends, minutely 

 ciliate, with raised viscid glands on 

 the nerves and margins ; panicles pale 

 green, at first partly included, later 

 short-exserted, 3 to 7 cm. long, 8 to 

 12 mm. thick; spikelets usually 5- 

 flowered, 6 to 7 mm. long; lemmas 

 flabellate, very broad, 5 mm. long, 

 ciliolate-f ringed, the many nerves 

 viscid-glandular at maturity. O 

 (Anthochloa colusana (Davy) Scribn.) 

 — Bordering rain pools on hard alkali 



