POLYGONACEOUS 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 2 
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 U. S. Herb. Remarkable for long and slender small-flowered 
spikes, with canescent bracts. 
P. RotHrocki. Rather slender, erect, very leafy with a short- 
petioled ascending thin and taper-pointed foliage; the inter- 
nodes and even the ocreæ 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 
incarnatum, 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. 1779, 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 
