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RYDBERG: NOTES ON ROSACEAE 489 
rivale L. and G. urbanum L., has been known for a long time. 
Geum rivale L. hybridizes also here in America and the following 
hybrids have been known. As the flowers of G. rivale are quite 
different from those of most species-of the genus, its hybrids are 
easily distinguished. 
Geum rivale X strictum, G. auranthacum Fries, was the first 
one to be recognized. It was described from garden material, 
but the following native specimens are to be referred here: 
ALBERTA: Macoun 20016. 
NEw York: Catskills, near Hunter, 1898, Britton; shores of 
Lake Champlain, 1900, V. L. & E. G. Britton. 
Geum macrophyllum X rivale, G. pulchrum Fern., is represented 
by the following specimens: 
VERMONT: Mendon, Eggleston. 
QUEBEC: Bic, 1905, Williams, Collins & Fernald. 
The hybrids between the species of the G. strictum group are 
not so easily distinguished, partly because the species themselves 
are closely related and seemingly grade into one another. As the 
intergrading forms are found in the region where the ranges of 
two species overlap, they may represent hybrids. As examples 
of such hybrids may be given the following specimens: 
Geum oregonense X strictum. 
Utan: Logan, 1910, George Zundel 206 (in part). 
Montana: Helena, 1908, Butler 708. 
CoLtorapo: Honnold, 1901, Tweedy 4172. 
Geum macrophyllum X oregonense. 
British CoLtumsiA: Scagit Valley, 1905, J. M. Macoun 69914. 
Wyominc: Crevasse Mountain, Yellowstone Park, 1902, 
Mearns 2791. 
Montana: Tobacco Mountains, 1909, Butler 4231. 
OREGON: Oregon City, 1905, Lyon 60. 
Geum macrophyllum X strictum. 
Montana: Lake McDonald, 1901, MacDougal 9590. 
SIEVERSIA 
This genus was based on Sieversia anemonoides and hence 
monotypic. In 1823 Robert Brown extended the genus to include 
1 the Geums without articulate styles. This limitation was 
