76 PLANTS OF YELLOWSTONE NATIONAL PARK 
Drymocallis fissa (with yellow flowers), D. glandulosa, and D. 
rupestris have also been reported in the park. 
Sibhaldia procumbent is a dwarf, perennial herb with rather thick, 
compound leaves. The densely clustered, creeping stems are 2 to 8 
inches long with the leaves mostly at the ends. The three leaflets are 
wedge-shaped and somewhat short-hairy. The yellow flowers are 
borne on leafless stalks. 
Horkelia gordonii is a perennial herb with pinnate leaves and yel¬ 
low flowers. The leaves are all basal and have 10 to 20 pairs of leaf¬ 
lets, which are pinnately divided into 3 to 5 narrow segments. 
Figure 55.—Spirea. White. Photograph Figure 56. —Cinquefoil. Yellow. Photo- 
by Joseph S. Dixon, National Park graph by Joseph S. Dixon, National Park 
Service. Service. 
Silverweed ( Argentina anserina) is a perennial herb with basal 
leaves and long runners. The yellow flowers are borne on long stalks 
in the axils of the leaves. The leaves are pinnate and have 
7 to 21 leaflets, with smaller ones interposed between. The leaflets 
are sharply toothed, green and smooth above but silvery-silky below. 
Silver cinquefoil ( Argentina argentea) is similar but stouter, and 
the leaves are silvery-silky on both sides. 
Cinquefoil (Potentilla) .—The cinquefoil has alternate, compound 
leaves with stipules and mostly yellow flowers. It is sometimes con¬ 
fused with the buttercup but the flowers of the cinquefoil have 5 
green sepals and 5 alternating bractlets, giving an appearance of 10 
sepals, while the buttercup has only the 5 sepals. The 16 species 
