BRIEFER ARTICLES 



A NEW SPECIES OF ANDROPOGON 



Andropogon urbanianus, n. sp. — Perennis; culmis glabris, 60-120 

 cm. altis; laminis teretibus, glabris; racemis binis, 2-4 cm. longis, 

 vagina longioribus; rachi villoso; spicula sessili glabra, a basi villosa, 5 

 mm. longa, arista 2 cm. longa; pedicelli sterili villoso, 5 mm. longo, 

 spicula pedicellata 3 mm. longa. 



Perennial; culms glabrous, 60-120 cm. high, branched above, 

 sheaths villous on the margin and toward the summit, or glabrate; 

 ligule membranaceous, ciliate, 2 mm. long; blades terete, channeled 

 above, glabrous, the two margins of the channel scabrous, villous above 

 at base, 10-20 cm. long, about 1 mm. thick, tapering to a fine point; 

 racemes 2 from each sheath, silky but not densely so, 2-4 cm. long, 

 scattered along the upper part of the culms, usually of unequal length, 

 the rachis joints slender, villous with long hairs, the subtending sheath 

 shorter than the racemes; sessile spikelets 5 mm. long, glabrous, villous 

 at base, scabrous above on nerves and keels, the awn geniculate, twisted 

 below, 2 cm. long; sterile pedicel about as long as sessile spikelet, villous 

 with hairs as much as 1 cm. long; pediceled spikelet reduced to a scale 

 3 mm. long. 



specimen 



Miguel 



Other specimens 



W 



Camache (St. Michel) 



D.C. 



— A. S. Hitchcock, Washington 



EVAPORATION AND THE STRATIFICATION OF 



VEGETATION 



(with one figure) 



During some investigations of the evaporating power of the air in 

 various plant associations, data were obtained that show the amount of 

 increase in the atmospheric humidity of the confined area of a ravine, 

 and that tend to emphasize the contention of Yapp 1 that the varying 



1 Yapp, R. H., On stratification in the vegetation of a marsh, and its relations to 

 evaporation and temperature. Ann. Botany 23:275-320. 1909. 



Botanical Gazette, vol. 54] k 24 



