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



Figure 1103. — Bouteloua tri 

 fida. Panicle, X 1; spike 

 let, X 5. (Amer. Gr. Nat 

 Herb. 669, Tex.) 



105. CATHESTECUM Presl 



Spikes consisting of 3 spikelets, the upper or central perfect, the 

 2 lateral staminate or rudimentary, the spike falling entire; central 

 spikelet with one perfect floret below and one or more reduced 

 florets above; glumes unequal, the first a short, 

 thin, nerveless scale in the central spikelet, nar- 

 row and acuminate in the lateral spikelets, the 

 second about as long as the lemma, acuminate, all 

 usually villous; lemma 3-nerved, the nerves ex- 

 tending into awns and the internerves into teeth ; 

 nerves of the palea extending into short awns; 

 second and third floret with a fairly well developed 

 lemma and palea, the fourth floret, if present, usu- 

 ally reduced. Low tufted or stoloniferous annu- 

 als or perennials, with short blades, and several to 

 many short deciduous spikes approximate on a 

 slender flexuous axis. Type species, Cathestecum 

 prostratum Presl. Name from Greek kathestekos, 

 set fast, stationary, the application not obvious. 

 1. Cathestecum erectum Vasey and Hack. 

 (Fig. 1105.) Perennial with wiry stolons having 

 arched internodes and hairy nodes ; culms slender, 

 10 to 30 cm tall; blades flat, about 1 mm wide, 

 mostly basal; spikes 4 to 8, ovoid, about 5 mm 

 long; lateral spikelets about two-thirds as long as the central spike- 

 let; lemmas of all spikelets similar, the sterile ones more deeply lobed; 

 awns from about as long as the lobes to twice as long, hairy at base. 

 Ql — Dry hills, western Texas, southern Arizona, and northern 

 Mexico. 



106. MUNROA Torr. 



Spikelets in pairs or threes on a short rachis, the lower 1 or 2 

 larger, 3- or 4-flowered, the upper 2- or 3-flowered, the group (reduced 

 spikes) enclosed in the broad sheaths of short 

 leaves, usually about 3 in a fascicle, forming a 

 cluster or head at the ends of the branches; 

 rachilla disarticulating above the glumes and 

 between the florets; glumes of the lower 1 or 

 2 spikelets equal, 1 -nerved, narrow, acute, a 

 little shorter than the lemmas, those of the 

 upper spikelet unequal, the first much shorter 

 or obsolete; lemmas 3-nerved, those of the lower 

 spikelet coriaceous, acuminate, the points spreading, the midnerve 

 extended into a mucro, those of the upper spikelet membranaceous; 

 palea narrow, enclosing the oval, dorsally compressed caryopsis. 

 Low spreading, much-branched annual, the short, flat, pungent 

 leaves in fascicles. Type species, Munroa squarrosa. Named for 

 William Munro. 



1. Munroa squarrosa (Nutt.) Torr. False buffalo grass. (Fig. 

 1106.) Forming mats as much as 50 cm in diameter, the internodes 

 of the prostrate culms scabrous, as much as 10 cm long, the fascicles 



Figure 1104.— Distribution of 

 Bouteloua trifida. 



