210 URTICACEAE 



2. PARIETArIA (Tourn.) L. Pellitory. 



Annual or perennial herbs, with diffusely branched, often pellucid stems, 

 polygamous. Leaves alternate, with 3-veined blades. Involucres of 2-6, more 

 or less united bracts. Flowers in axillary cymes. Perianth of 4, rarely 3, more 

 or less united sepals. Stamens 4, rarely 3, in the perfect and the staminate flow- 

 ers, ha the pistillate ones wanting. Pistils solitary, in the staminate flowers 

 rudimentary; stigmas tufted. Achenes included, with a crustaceous pericarp. 



Leaf-blades lanceolate. 2-7 cm. long, twice as long as the petioles or longer. 



Plant comparatively dark green; stem densely puberulent; sepals lanceolate, acute, 



1 P J) €7l7t SvlVQ'Tli'CQ' 



Plant very Ught green; stem long- villous; sepals ovate, often obtuse. 



2 ^^ {ifciflPTitfilis 



Leaf-blades oblong or ovate-oblong, 0.5-2 cm. long, not twice as long as the petioles. 



3. P. obtusa. 



1. P. pennsylvanica Muhl. Annual, slender; stem weak, ascending, 1-4 



dm. high, smiple or branched; leaf-blades thin and flimsy, obtuse or acuminate 



at the apex, acute or acuminate at the base; bracts of the involucre hnear, 4-5 



mm. long. Shaded banks or rocks: Ont.— Fla.— Mex.— B.C. Plain— Sub- 

 TYiont, My-Au. 



2. P. occidentalis Rydb. Annual; stem slender, erect, simple or branched 

 at the base, 1-4 dm. high; leaf -blades thin, light green, acute at the base, obtus- 

 ish at the apex, 1-4 cm. long, 5-18 mm. wide, sparingly pubescent; bracts of the 

 involucre linear, obtuse. Moist shaded places: Wash. — Ida. — Nev. Suhmoni. 

 My-Au. 



3» P. obtusa Rydb. Annual; stem usually branched at the base, spreading, 

 5-20 cm. long, finely villous; leaf -blades obtuse; bracts of the involucres oblong 

 or narrowly oblong, obtuse; sepals ovate, obtuse, rarely acutish. Shady places: 

 Colo.--Utah— s Calif.— Tex. Son.—Suhmoni, F-Jl. 



Family 37. POLYGONACEAE. Buckwheat Family. 



Herbs or shrubs, or in the tropics trees or vines, with alternate leaves. 

 Flowers perfect or rarely unisexual. Calyx inferior, of 2-6 more or less 

 united sepals, often coroUoid. Corolla wanting. Stamens 2-9. Pistil of 

 2 or 3 united carpels, but ovary 1-celled, in fruit becoming a 1-seeded, tri- 

 angular or lenticular achene. 



■ 



Leaves without stipules; flowers or flower-clusters subtended by involucres of oartlv 



united bracts; stamens mostly 9. Jf ^ "^^^^ "^ *'*» ^'-j 



Involucres from tubular to campanulate. of several united bracts 



Involucres awnless, campanulate or turbinate, 4-8-toothed or -lobed. 



T , ■ ^ _, 1- EmoGONiTM. 



Involucres awn-pointed. 



Involucres herbaceous; flowers exserted; achenes lenticxilar. 



Involucres leathery or homy; flowers included; achenes 3-*angled 



Involucres with 3-6 awn-tipped spurs near the base, 1-3-flowered, in open 



dichotomous panicles. 3, centrostegia. 



Involucres without spurs, 1-flowered. 



Involucres 6-angled, sulcate; filaments adnate to the base of the peri- 



iiiJluLl. A O'HORf ZATVTHE 



Involucres 3-angled; filaments adnate to the whole tube of the perianth. 



Involucres bract-like. 2-cleft. - %• ^^tl™?S?l['''^- 



'^^^SV mi^tu^fted^^^ stipules (ocreae); flower-clusters not involucrate; stamens 4-8. ' 



Sepals 6; styles 3; achenes triangular. 7 rtimfx 



Sepals 4; styles 2; achenes lenticular. L' oxyrVa 



Stigmas not tufted. ^- ^^aykia. 



^^£;^K%i'^''^^'''^ ^V?^®J^^^' ^^^^ 2-lobed. becoming lacerate; filaments. 

 at least the inner, dilated. 9 polycunlm 



Leaf^blades not jointed at the base; ocreae not 2-lobed; filaments slender. 

 Ocreae cyhndnc, truncate. XO Persicarii 



Ocreae obhque. more or less open on the side facing the leaf 



Herbs, not cUmbing or twining; sepals neither winged nor keeled. 



* lo were m simple spike-Uke racemes; plants with thickened tuberous 



roOtstOCks. 11^ BISTORTA. 



