POLTGOSTACEOtTS GENERA. 45 



with traces of muriate-scabrous hair -points on the veinlets and 

 near the margin, those next above closely muricate-scabrous both 

 superficially and on the midvein as well as veinlets, the others 

 narrower and elliptic-lanceolate, more taper-pointed, somewhat, 

 silvery-strigulose on both faces, the midvein beneath with 

 coarser and even slender-conical appressed hairs : peduncles 3 

 inches long, sparsely beset with ascending short gland-tipped 

 hairs : spikes remarkably narrow, 3 or 4 inches long, the flowers 

 small ; bracts canescently strigose, not ciliate : achenes round- 

 ovate, unusually thin and compressed, not highly polished, of a 

 light chestnut-brown. 



Rattlesnake Tanks, Arizona, 1 Aug., 1891, D. T, McDougal, 

 in TJ. S. Herb. Remarkable for long and slender small-flowered 

 spikes, with canescent bracts. 



P. RoTHKOCKii. Rather slender, erect, very leafy with a short- 

 petioled ascending thin and taper-pointed foliage; the inter- 

 nodes and even the ocrese glabrous : leaves of lanceolate outline 

 but slender-pointed, above either glabrous or with scattered and 

 inconspicuous hair-points, especially on the veinlets, beneath 

 less roughened superficially but more so on the unusually prom- 

 inent veinlets, the hair-points of the midvein subulate-spinulose, 

 appressed : spikes and glandular-scabrous peduncles both short, 

 little exceeding the leaves ; bracts of the short cylindric spike 

 spinulose-ciliolate and with scattered hair-points on the back. 



Shores of ponds, streams and ditches of the hot and arid 

 regions along the Mexican boundary; good type-specimens being 

 Rothrock's n. 670 (as in U. S. Herb.); Toumey's " Polygonum 

 intarnatum. Ell." from along an irrigating ditch at Tucson; a 

 sheet by Dr. Palmer from " Arizona, 1869 " ; while for older 

 and more classic but poor material one may cite Charles Wright's 

 n. Vil^, besides a couple of fragments in U. S. Herb, from the 

 Mexican Boundary Survey, these mounted on a sheet with a 

 larger specimen of another species, all under n. 1184. 



In a general way unlike the foregoing group in habit, being of 

 lower stature, denser leafiness, with usually subsessile and 

 spreading leaves, is an aggregate which has passed under the 



