From lightly hairy to densely so or nearly smooth, 1—2 feet high. Leaves rather thin, hairy, oblong to oblong-lanceolate, dentate or denticulate, acute or obtuse, lowest tapering into a margined petiole, upper broad at the base and somewhat clasping. Heads ½ an inch or more high, single or several on hairy peduncles; involucral bracts ⅓ of an inch or more long, oblong-lanceolate, acuminate, glandular-hairy; rays bright yellow, ½ an inch or more long with a single notch at the apex, rather broad; achenes with a few scattered hairs; pappus tawny. On the borders of streams and wet places at the lower altitudes throughout the region; flowering in July. [Sidenote: =Arnica louiseana= Farr. _Pale-flowered Arnica._] Slender, hairy, 3—8 inches high. Leaves in about 3 pairs, the two lowest at the base of the stem, 1½—2 inches long, elliptical or obovate, entire or denticulate, glandular-hairy on both surfaces, as are the margins. Heads of flowers, 1—3, nearly half an inch broad, on long, slender, nodding, hairy peduncles; rays 8—10, light yellow, about ½ an inch long; involucre ⅓ of an inch high, campanulate, densely glandular-hairy at the base, brownish-purple, the bracts lanceolate, acute, with scattered white hairs; pappus white. Among loose stones at the base of Mt. Fairview at Lake Louise; flowering in July. [Sidenote: =Arnica fulgens= Pursh. _Alpine Arnica._] Glandular-hairy throughout, 8—12 inches high. Leaves oblong lanceolate to lanceolate, acute, the lower denticulate and petioled, the upper sessile and entire. Heads of flowers several on long, slender, glandular-hairy peduncles; involucres campanulate, ½ an inch high, bracts lanceolate acute, glandular and with long white hairs; rays bright yellow ¾—1 inch long, ¼ of an inch wide, twice notched at the apex; achenes hairy; pappus white. On stony alpine slopes at the higher altitudes throughout the Rockies; flowering in July. [Sidenote: =Arnica eradiata= (A. Gray.) Heller. _Rayless Arnica._] Densely soft-hairy throughout; simple or branched, 12—18 inches high. Leaves oblong, ovate-lanceolate or the upper ones lanceolate, obtuse or acute, entire or sharply denticulate, 1—3 inches long. Heads of flowers on short, hairy peduncles, without rays; involucre ½ an inch high, bracts lanceolate, acute; achenes black, smooth or nearly so; pappus tawny. On grassy alpine slopes through the Rockies at the higher elevations; flowering in July. [Sidenote: =Senecio pseudaureus= Rydb. _Western Golden Ragwort._] Smooth from a creeping rootstock, 1—2 feet high. Leaves smooth, basal broadly ovate, somewhat cordate, serrate, 1½—3 inches long, long-petioled; stem leaves more or less laciniate at the base, the upper sessile. Heads of flowers ⅓ of an inch high in a flat-topped corymb, rays bright orange-yellow, ⅓ of an inch long. In moist ground and borders of woods and slopes throughout the Rockies at the lower altitudes; flowering during June and early July.