GRIFFITHS THE GRAMA GRASSES. 



395 



The species appear to be native from San Luis Potosi northward. It is distin- 

 guished by its strong, harsh, woody base and by its spikes, which, although they 

 resemble those of B. barbata, are slightly wider and shorter. 



The first material seen was collected by myself near Alonzo, Mexico, March 14, 

 1905 (no. 7650). All specimens were of the previous year's growth, and consequently 

 not satisfactory. Recently Lloyd has contributed very materially to a knowledge of 

 the species by two collections (nos. 170 and 183) from Hacienda de Cedros, in north- 

 ern Zacatecas. These and a panicle of a duplicate of the type are all the material 

 which has been seen. 



18. Bouteloua alamosana Vasey. 



Bouteloua alamosana Vasey, Contr. Nat. Herb. 1 : 115. 1891. Edward Palmer's no. 

 698, Alamos, Sonora, Mexico, September 10 to 30, 1890, is the type. 



DESCRIPTION. 



A tufted, sparingly hairy annual with geniculate, ascending or prostrate, sparingly 

 branched culms, 4 to 20 cm. high; sheaths striate, rather loose, with scattered, papil- 



Fig. 48. — Bouteloua alamosana. a, Splkelet; 6, c, lemma and palet of first floret; d, e, rudimentary 

 lemma and palet of second floret; /, two views and cross-section of caryopsis; g, portion of leaf blade, 

 a-f, Scale 7.5; g, scale 2.5. 



lose hairs, especially near the edges, the ligule consisting of a white, ciliate fringe; 

 blades minutely hispid, especially above, and bearing long, papillose hairs at regular 

 intervals on the -margins and scattered and less numerous hairs on the surfaces; panicle 

 racemose, 2.5 to 4 cm. long; spikes 3 to 5, 10 to 15 mm. long, very similar to those of 

 B. texana, containing 3 to 5 spikelets, these often consisting of one floret and a rudi- 



