Carpels few; in fruit becoming 2-several sided. Stamens united at the base; flowers racemose. =Lutkea.= Stamens not united at the base; flowers in panicles or corymbs. Shrubs with simple leaves, flowers perfect. =Spiræa.= Herbs with compound leaves; flowers diœcious. =Aruncus.= Carpels few or many; in fruit becoming achenes or drupelets. Fruit consisting of drupelets, usually united. =Rubus.= Fruit consisting of achenes. Achenes enclosed in a fleshy fruit; prickly shrubs. =Rosa.= Achenes on a plane or concave receptacle; herbs. Styles deciduous, naked. Styles terminal. =Potentilla.= Styles lateral. Carpels hairy; shrubs. =Dasyphora.= Carpels smooth; herbs. Stamens 5; carpels 10—15. =Sibbaldia.= Stamens 20; carpels numerous. Leaves trifoliate; receptacle fleshy. =Fragaria.= Leaves pinnate; receptacle not fleshy. Flowers dark purple. =Comarum.= Flowers yellow. Plant with stolons; flowers solitary. =Argentina.= Styles persistent, mostly plumose. Calyx lobes and petals 8 or 9. =Dryas.= Calyx lobes and petals 5. Style jointed, upper part deciduous. =Geum.= Style not jointed, upper part plumose. =Sieversia.= [Illustration: Tiarella unifoliata Hook. (¼ Nat.) Western Foam-Flower.] [Illustration: Lutkea pectinata (Pursh) Kuntze. (⅔ Nat.) Cut-Leaved Lutkea.] [Sidenote: =Lutkea pectinata= (Pursh.) Kuntze. _Cut-leaved Lutkea._] Smooth, stems cæspitose, very leafy. Leaves trifoliate, persistent, leaflets deeply 2—4-lobed, the lateral ones decumbent, forming a broad petiole. Flowering stems 2—6 inches high with a dense terminal raceme of many white flowers, about ¼ of an inch broad; calyx lobes ovate, acute; petals 5, obovate, exceeding the calyx; stamens numerous, shorter than the petals. Frequent throughout the Selkirks, on alpine slopes and beside streams at the higher elevations; flowering in June. [Sidenote: =Spiræa densiflora= Nutt. _Pink Spiræa._] Stem 2—4 feet high, reddish. Leaves ovate or elliptical, serrulate at the apex, entire below, narrowed at the base to a very short petiole or the lowest sessile, dark green on both sides, ½—1 inch long. Flowers small, deep rose-colour in dense, round, leafy, bracted corymbs, terminating the numerous branches. In moist, exposed, rocky places and on slopes at the lower altitudes, frequent in the Selkirks; flowering in June. [Sidenote: =Spiræa lucida= Dougl. _Birch-leaved Spiræa._]