10 POLYGON ACE^:. Rumex. 



2. Flowers dioecious or polygamous, small : valves not grain-bearing : leaves 

 often hastate, sparingly veined. Glabrous perennials. ACETOSA and 

 ACETOSELLA, Meisner. 



* Valves enlarged in fruit : pedicels 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 leafy : leaves narrowly to linear-lanceolate, or the lowest broader, 2 

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

 naked panicle slender, erect : flowers 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. (?) Geyeri, 

 Meisner, DC. Prodr. xiv. 64. 



In the Sierra Nevada (near Lake Tenayo, Brewer) and 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 usually hastate, very acid. 



12. R. Acetosella, Linn. Very slender, 6 to 18 inches high : leaves oblong- 

 to linear-lanceolate or oblanceolate, 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 by its slender running rootstocks. 



3. POLYGONUM, Linn. KNOTWEED. 



Flowers perfect. Perianth of 5 or 6 (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 weeds. The juice of some species is very pungent or acrid, never acid ; roots often 

 astringent. 



1. Flowers in axillary fascicles or spicate with foliaceous bracts : leaves and 

 bracts jointed upon a very short petiole adnate to the naked 2-lobed or 

 lacerate sheath, obscurely pinnate-veined or veinless : perianth 5 6- 

 parted, usually more or less herbaceous : stamens 3 to 8, the 3 inner fila- 

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



* Smooth perennials with chestnut-brown stems woody at base, the slender branches 

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

 what spreading even in fruit. 



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

 branches leafy or covered with old sheaths : sheaths large (^ inch long or more), 

 brown and 5-nerved at base, finely 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 pedicels ; sepals oblong-obovate : 



