Flowers not involucrate; stipules sheathing. Leaves reniform, sepals 4. =Oxyria.= Leaves not reniform; sepals 6. Sepals unequal; stigmas tufted. =Rumex.= Sepals equal; stigmas capitate. =Polygonum.= Flowers involucrate, many; stipules wanting. =Eriogonum.= [Sidenote: =Oxyria digyna= (L.) Hill. _Mountain Sorrel._] Stems 2 inches to a foot high, scape-like and leafless, from a large chaffy rootstock. Leaves basal on long petioles, reniform or orbicular ½—2 inches wide with a wavy margin, sometimes notched at the apex. Racemes 2—3 inches or more long, of many small flowers on slender pedicels; crimson or pinkish and showy in fruit. Frequent at the higher altitudes throughout the region in moist grounds and beside streams, flowering in June. [Sidenote: =Rumex acetosa= _Sour._] Stems a foot or more high, smooth. Leaves oblong, hastate or ovate-sagittate, 1—4 inches long, acute, the basal few and long petioled, stem leaves sessile, the acute auricles entire. Flowers, diœcious, minute, crowded in a slender head 3—6 inches long, yellowish-green tinged with red. In moist open ground at the higher elevations, more or less frequent throughout the Rockies, flowering in midsummer. [Sidenote: =Rumex salicifiolus= Weinm. _Pale-leaved Dock._] Smooth, pale green, erect, and spreading, 1—3 feet high. Leaves lanceolate, acute or acuminate at both ends, petioled. Flowers small greenish-white in erect or reflexed racemes, dense in fruit, interrupted below; wings of the fruit triangular-ovate, with a large ovoid tubercle. Frequent throughout the Rockies at the lower altitudes; flowering in summer. [Sidenote: =Polygonum viviparum= L. _Alpine Bistort._] Smooth, with a corm-like rootstock; stems solitary or clustered, 2—10 inches high. Basal leaves lanceolate or oblong. 1—8 inches long, rather acute, cordate at the base on long petioles; stem leaves narrowly lanceolate or linear, upper sessile with revolute margins. Flowers in a dense terminal raceme several inches long; rose-coloured or white; stamens exserted; small bulblets frequently developed among the flowers, which later produce leaves and young plants. Frequent in moist sandy soil and river banks throughout the Rockies, flowering in June and July. Several small weedy species of the genus are also found through the region but are not sufficiently striking to be here described. [Sidenote: =Eriogonum subalpinum= Greene. _Tall White Eriogonum._] Stems depressed, much branched, prostrate and matted at the base. Leaves oblong to ovate-spatulate, 1—2 inches long, on slender petioles, smooth and green above, white-woolly beneath. Scape-like peduncles, erect, 8—14 inches high, with a simple, large umbel of 8—12 rays subtended by a whorl of leaves. Flowers ⅛—¼ of an inch high, cream-coloured or nearly pure white, and tinged with rosy pink especially in age.