MANUAL OF THE GRASSES OF THE UNITED STATES 



217 



14. Triodia elongata (Buckl.) Scribn. Rough triodia. (Fig. 424.) 

 Culms erect, tufted, 40 to 80 cm tall; sheaths and blades scaberulous, 

 sometimes sparsely pilose, the blades mostly flat, 2 to 4 mm wide, 

 tapering to a fine point; panicle elongate, erect, pale or purple tinged, 

 loosely flowered, 10 to 25 cm long, the branches 

 rather distant, appressed, scarcely or not at all over- 

 lapping; spikelets similar to those of T. mutica, the 

 glumes longer, the hairs on the florets not so long. 

 91 (Tridens elongatus Nash; Tricuspis elongata 

 Nash.) — Plains, sandy prairies, and rocky slopes, 

 Missouri and Kansas to Texas and Arizona (fig. 425). 



32. TRIPLASIS Beauv. 



Spikelets few-flowered, V-shaped, the florets re- 

 mote, the rachilla slender, disarticulating above the 

 glumes and between the florets; glumes nearly equal, 

 smooth, 1-nerved, acute; lemmas narrow, 3-nerved, 

 2-lobed, the nerves parallel, silky-villous, the lateral 

 pair near the margin, the midnerve excurrent as an 

 awn, as long as the lobes or longer; palea shorter 

 than the lemma, the keels densely long-villous on 

 the upper half. Slender tufted annuals or perennials, 

 with short blades, short, open, few-flowered purple 

 terminal panicles and cleistogamous narrow panicles 

 in the axils of the leaves. Both species, have, in 

 addition to the small panicles of cleistogamous spike- 

 lets in the upper sheaths, additional cleistogamous 

 spikelets, reduced to a single large floret, at the 

 bases of the lower sheaths. The culms break at the 

 nodes, these mature 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. (Fig. 

 426, A) Annual, often purple; culms ascend- 

 ing to widely spreading, pubescent at the 

 several to many nodes, 30 to 75 cm tall; 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; lemmas 

 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 



Figure 424.— Triodia 

 elongata. Panicle, X 

 1; two views of floret, 

 X 5. (Ball 1535, 

 Tex.) 



Figure 425.— Distribution of 

 Triodia elongata. 



