20 POLYGONACEJi:. Rumex. 



§2. Flowers d'neclous or j)oli/fjaviom, small: valoes not grain4>earlng : leaves 

 often hastate, sparinr/ji/ veined. Glabrous 2'(^rennials. — §§ Acetosa and 

 AcETOSELLA, Mt'isiier. 



* Valves enlarged in fruit : j>edicels filiform, jointed at base: roots thickened: 



leaves not hastate nor very acid. 



11. R. paucifolius, Nutt. Stems erect and slender, a foot or two high or 

 more, sparingly leaiy : leaves narrowly to linear-lanceolate, or the lowest broader, 2 

 to 4 inches long, acute or acutish, attenuate to a slender petiole : bmnches of the 

 naked panicle slender, erect : Howers reddish, in loose fascicles, half a line long or 

 less, fruiting sparingly : valves cordate-ovate, entire, nearly 2 lines long, twice longer 

 than the akene. — Watson, Bot. King Exp. 314. R. Engelmanni, var. (1) Geijtri, 

 Aleisner, DC. Prodr. xiv. 64. 



In the Sien-a Nevada (near Lake Teiiayo, Brewer) ajul northward to Washington Territory, 

 ranging east to Montana and Utah. 



* * Valves not enlarged nor exceeding the small akene: pedicels very short, 

 jointed at the top : roots slender, running : leaves iisuallg hastate, very acid. 



12. R. Acetosella, Linn. Very slender, G to 18 inches high: leaves ohlong- 

 to linear-lanc(;olatc or oltlaiiceolate, an inch or two long, usually hastate, the narrow 

 lobes often toothed at base ; petioles slender : panicle narrow, naked, becoming red- 

 dish : flowers very small, in loose fascicles : fruit triangular-ovate, two thirds of a 

 line long or less, exceeding the pedicels. 



A very widely spread weed from Europe, the common " sorrel " of fields and gardens, spread- 

 ing rapidly in light soils hy its slender running rootstocks. 



3. POLYGONUM, Linn. Knotweed. 



Flowers perfect. Perianth of 5 or G (rarely 4) nearly distinct often petal-like 

 sepals, nearly equal and mostly not enlarging in fruit, erect and appressed upon the 

 3-angled or lenticular akene. Stamens 4 to 9. Styles 2 or 3, distinct or connate, 

 often very short : stigmas capitate. Embryo lateral, curved, half immersed at one 

 angle of the usually horny albumen; cotyledons usually narrow. — Annual or per- 

 ennial leafy herbs, rarely woody at base ; sheaths naked, ciliate, or foliaceous-mar- 

 gined ; flowers small, in axillary, spicate, or racemose fascicles. 



A genus of 200 species, distributed over the globe, of little or no value, a few very widely nat- 

 uralized as wee.is. Tlie juice of some species is very pmigcnt or acrid, never acid ; roots ol'ten 

 astringent. 



§ 1. Flower.^ in axillary fascicles or silicate, irifh foliaceous bracts: leaves and 

 bracts jointed v^ion a, very short petiole itdnate to the naked '2,-lubcd or 

 lacerate sheath, obsawely jnnnate-veined or veinlcis : perianth r)--()- 

 jmrted, usually more or h'ss herbaceous: stamens 3 to 8, the 3 inner fila- 

 ments broad at base: styles 3 : akene triangular. — Aviculauia, Meisn. 

 * Smooth perennials %oith chestnut-bro^on stems ivoody at base, the slender branches 

 leafy to the top: leaves thick; sheaths consjncuous : sepals colored, some- 

 what spreading even in fruit. 

 1. P. Paronychia, Cham. & Schlecht. Prostrate, branching, 1 to 3 feet long; 

 branches leafy or covered with old sheaths : sheaths large {h inch long or more), 

 brown and 5-nerved at base, flnely lacerate above, persistent : leaves linear-lanceo- 

 late, a half to an inch long, acute, the margin revolute : flowers densely crowded 

 at the ends of the branches in short more or less leafy spikes, rose-colored veined 

 with green or brown, 3 lines long, on very short jiedicels ; sepals oblong-obovate : 



