88 MISSOURI BOTANICAL GARDEN. 
cluster longer, jointed near the base; valves 2 to3x4to 5 
mm., triangular ovate, acute, more delicately veined ; cal- 
losities variable in number, smooth or mostly pitted, often 
nearly as long as the valve, 1 mm. or more broad, leaving 
typically a very narrow margin on each side; achene 
1.3x 1.7 to 2.5 mm.—Flora, 1821, 28; Meisner, DC. 
Prod. xiv. 47.—Arctic “America across to Alaska, south to 
New Hampshire, the Great Lakes, and in the mountains to 
Southern California and Mexico, where it closely approaches 
R. Mexicanus. — Specimens examined from various British 
American points between New Brunswick and Vancouver 
Island; Alaska ( Tiling, 1867, 394); and Maine (Booti, - 
1861; Rand, 1888), New Hampshire (Oanby, 1866), 
Ashland, Wisconsin (Farwell, 1887), Keweenaw Co., Mich. 
(Farwell, 1890), Western Missouri! (Bush, 1890), Wash- 
ington, Oregon (Hall, 1871, 441; Lyall, 1858, 1860; 
Howell, 1882), California, Montana ( Scribner, 1883, 246), 
Idaho, Wyoming (Forwood, 1882, 177), Colorado, Utah 
(Ward, 1875, 540; Palmer, 1877, 421), New Mexico 
(Fendler, 1847, 760 and 761; Rusby, 1880), Arizona 
( Coues and Palmer, 1865), Nevada ( Watson, 1868, 1051), 
Texas (Merrill, 1886), and Lower California (Orcutt, 
1884).— Plate 26. 
As here accepted, this species comprises several forms so 
far as the fruiting valves and achenia are concerned. The 
Asiatic form is said to have only one or two of the valves 
with callosity. In this respect two principal American 
forms may be distinguished: —a, with valves deltoid or 
abruptly acuminate, often evidently denticulate below, the 
margin conspicuous on either side of the frequently solitary 
callosity; 5, with valves more narrowly triangular, nearly 
or quite entire, nearly concealed by the mostly 3 large 
callosities. The first in its more toothed form is var. 
denticulatus, Torr. Bot. Mex. Bound. (1859), 178. The 
second in its most pronounced form is var. angustifolius, 
Ledebour, Fl. Ross. iii. (1849), 504. It may be that 
these forms will bear separation, even from the Old World 
type; but the (frequently young) specimens in herbaria 
