Rootstock short, creeping, and densely chaffy; stems brown, darker at the base, 2—4 inches long, glandular-hairy; leaves mostly glandular-hairy throughout, lanceolate, 6—12 inches long, tapering from about the middle to both ends; pinnæ numerous, oblong-ovate, pinnatifid into oblong-toothed segments; sori nearly marginal. In crevices in the rocks and among broken stones on slides, throughout the Rockies, up to an elevation of 7000 feet; frequent. [Sidenote: =Woodsia oregana= D. C. Eaton. _Oregon Woodsia._] Rootstock short; stems smooth, brownish below. Leaves smooth, 2—10 inches long, lanceolate; pinnæ triangular, oblong, obtuse, pinnatifid, lower ones rounded and somewhat remote from the others; rachis straw-colored; pinnules oblong-ovate, dentate or crenate, the teeth often turned back and covering the submarginal sori. Among broken stones on the slides near the base of Mt. Stephen in the Rockies. [Sidenote: =Filix fragilis= (L.) Underw. _Brittle Fern._] Rootstock short; stems 4—8 inches long, leaves thin, smooth throughout, oblong-lanceolate, only slightly tapering below, 4—10 inches long; pinnate or 2—3 pinnatifid; pinnæ lanceolate-ovate, irregularly pinnatifid with a broad central space, and bluntly or sharply toothed segments, decurrent along the margined or winged rachis; sori small, half way between the margin and the midrib; indusium narrow, soon withering. In crevices in rocks and among broken stones throughout the Rockies. [Sidenote: =Filix montana= (Lam.) Underw.] Rootstock slender, widely creeping; stipes 6—9 inches long, slender; leaves deltoid-ovate, 3—4 pinnate, 3—6 inches broad, the lowest pinnæ triangular-lanceolate and much larger, their inferior pinnules 1—1½ inches long, deeply divided into oblong lobes, deeply toothed; sori numerous; indusium acute, soon withering. On damp mossy banks and rocks throughout the Rockies; not common. EQUISETACEÆ _Horsetail Family_ Green, rush-like plants with usually hollow, jointed, simple or often much branched stems, rising from subterranean rootstocks; the branches verticillate. Leaves reduced to toothed sheaths; sporanges clustered beneath the scales of terminal, cone-like spikes. [Sidenote: =Equisetum arvense= L. _Field Horsetail._] Stems annual, the fertile appearing in early spring before the sterile; fertile stems 4—10 inches high, soon withering, light brown, their loose sheaths mostly distant, whitish, ending in about 12 brown acuminate teeth; sterile stems green, much branched and slender, 2 inches to 2 feet high with numerous, mostly simple, 4-angled solid branches with 4-toothed sheaths. In moist sandy soil throughout the region, frequent in wet woods and swampy places. [Sidenote: =Equisetum sylvaticum= L. _Wood Horsetail._]