9(3). Valves without grains and as measured (including the basal lobes) altogether 

 about 5 mm. long and 5 mm. broad, rarely more. ...9. R. occidentalis. 



9. One or more of the valves bearing a grain dorsally (10) 



10(9) . Valves entire-margined to slightly erose (11) 



10. Valves denticulate to setaceously toothed (12) 



11(10). Leaves large, somewhat crisped or undulate, often narrowed at base, sel- 

 dom truncate; valves (3.5-) 4-6 mm. long; only the lower whorls 

 with bracteal leaves and occasionally remote 10. R. crispus. 



11. Leaves small, flat and truncate; valves very small, scarcely broader than the 



thick grains; whorls remote and nearly all with bracteal leaves 



1 1. R. conglomeratus. 



12(10). Plants glabrous throughout; leaves elliptic-lanceolate, with noticeably 

 crenate-undulate margins; the 3 grains nearly equally developed 

 12. R. stenophyllus. 



12. Plants with minute pubescence either on leaf stalks, lower surface of at least 



the lower leaves or on the stem; leaves plane, typically with smooth 

 margins; the grains equally developed or not (13) 



13(12). Perennials; basal leaves at most 2.5 times as long as broad, cordate at 

 base; valves broadly ovate to triangular-ovate, 4-6 mm. long (14) 



13. Annuals or biennials; basal leaves 3 or more times as long as broad; valves 



narrowly triangular-ovate, rarely to 3.5 mm. long (15) 



14(13). Leaves large; pedicels slender, nearly twice as long as the mature fruit; 

 mature grain smooth or only lightly wrinkled 13. R. obtusifoUus. 



14. Leaves small; pedicels stout, one fourth as long to nearly as long as the mature 



fruit; mature grain coarsely warty 14. R. pulcher. 



15(13). Pedicels stout, thickish; valves very shortly dentate; leaves obcordate- 

 lanceolate, mostly widest above the middle, about 3 times longer 

 than broad 15. R. violascens. 



15. Pedicels long, slender; valves usually long-dentate; leaves linear-lanceolate, 



mostly many times longer than broad 16. R. maritimus. 



1. Rumex Acetosella L. Sheep sorrel. Fig. 398A. 



Perennial with slender running rhizomes; stems numerous, slender, wiry, erect 

 or decumbent at base, usually unbranched, 2-4 dm. tall, scabrous; leaves linear to 

 lanceolate, 2.5-8 cm. long, hastate, the basal lobes usually large, the petioles of 

 lower leaves often longer than the blades; panicles many-branched, the glomerules 

 without subtending leaves; flowers usually unisexual, occasionally polygamous, the 

 pistillate flowers turning red in age; pedicels as long to twice as long as mature 

 perianth, not articulated; valves entire, not enlarging in fruit, about 1 mm. long, 

 scarcely as long as the achene, lacking callous grains and without distinct nerva- 

 tion; achene about 1 mm. long, almost as broad, the surface smooth and shiny, 

 mahogany red. Acetosella acetosella (L.) Small. 



Waste places, often in swampy areas, in wet mud about lakes and pools, along 

 railroads and open fields, rare in e. Okla. {Waterfall), cen. Tex., N.M. (Lincoln 

 Co.) and Ariz. (Coconino Co.), summer-fall; Euras. weed now widely adv. 



The sour leaves, which can be used to quench thirst or prepare an acid beverage 

 may be used similarly to water cress in salads and as a seasoning for various dishes, 

 as well as for a potherb. Some individuals are known to have mild dermatitis from 

 handling the plants while others may have hay fever from its profuse pollen. 



Although several other species of Rumex have some value for wildlife, this 

 species is by far the most important. Both its seeds and herbage are eaten by 

 most kinds of wildlife. 



798 



