84 POLYGONACEAE. 



Flowers dioecious; plants small. 



Inner sepals not longer than the granular akene; leaves 



hastate. R. acetosella. 



Inner sepals longer than the smooth akene; leaves lan- 

 ceolate. R. pancifolius. 

 Flowers not dioecious; plants large. 



Outer sepals without tubercle-like thickenings in fruit. 



Fruiting valves cordate, 15-25 mm. long. R. venosus. 



Fruiting valves ovate, 6-10 mm. long. R. occidentalis . 



Outer sepals with tubercle-like thickenings in fruit. 



Annuals; valves with bristle-like teeth. R. persicarioides. 



Perennials; valves denticulate. 



Leaves crisped on the margins. R. crispus. 



Leaves flat. R. mexicanus. 



Rumex acetosella L. Sheep Sorrel. Dioecious, widely spreading by 

 creeping rootstocks; stems slender, 10-30 cm. high, simple or somewhat 

 branched; leaves 3-10 cm. long, very acid, glabrous, mostly hastate, the basal 

 lobes entire or toothed; sheaths scarious, becoming cut into lobes; panicle 

 narrow, the branches ascending; bracts wanting; flowers small, on short jointed 

 pedicels, clustered; sepals remaining small, much shorter than the 3-angled 

 akene. Introduced, a weed in lawns and pastures. 



Rumex paucifolius Nutt. Dioecious; stems erect and slender, 30-60 cm. 

 high, sparingly leafy; leaves narrowly to linear-lanceolate, 5-10 cm. long, acute 

 or acutish, attenuate to a slender petiole, not very acid; panicle branches 

 slender, erect; flowers reddish, small, in loose fascicles; inner sepals longer than 

 the smooth akene. In wet meadows, infrequent. 



Rumex venosus Pursh. Stems 30-60 cm. tall, commonly woody, strongly- 

 grooved, erect or decumbent, from woody creeping rootstocks; leaves elliptic 

 or lanceolate, entire, acute at each end, 8-12 cm. long; petioles stout, rather 

 dense, 10-15 cm. long; valves bright red, cordate-orbicular, entire, very large, 

 1.5-2 cm. long, wholly without tubercles; akenes 6-8 mm. long. In sandy 

 soil especially on sand dunes. 



Rumex occidentalis Wats. Stout, 100-150 cm. tall; leaves oblong-ovate, 

 mostly obtuse, 15-40 cm. long, entire or undulate, cordate at the base; petioles 

 of the lower leaves long and slender, of the upper stout; panicles 30-60 cm. 

 long, dense, usually reddish; flowers on slender pedicels, 1 cm. long; valves 

 broadly ovate, obtuse, more or less toothed, 6-10 cm. long, wholly without 

 tubercles; akene brown, 4 mm. long. Common in swampy places. 



Rumex persicarioides L. Minutely pubescent; stems erect or procumbent, 

 branched, 1560 cm. high; leaves linear-lanceolate, truncate or slightly cordate 

 at base, 310 cm. long, wavy-margined; panicle dense, the flowers short-pedi- 

 celled in numerous close whorls; valves ovate, each bearing a tubercle on the 

 back and 2 or 3 slender bristles on the margins. In wet places, especially 

 where alkaline. 



Rumex crispus L. Yellow Dock. Stem stout, 50-100 cm. high, grooved, 

 from an elongated fusiform root; leaves oblong, obtuse, truncate or rounded 

 at the base, 15-30 cm. long, the margin wavy and crisped; petiole short; 

 panicle rather dense, 20-40 cm. long, greenish; flowers on pedicels 5-10 mm. 

 long; valves 3-4 mm. long, broadly ovate or cordate, each bearing a tubercle; 

 akene about 2-2.5 mm. long, brown. A weed in grain fields and along road- 

 sides. 



Rumex mexicanus Meisn. Stems erect or decumbent, 40-90 cm. long, 

 slightly grooved, often branched below; leaves oblong-lanceolate or linear- 

 lanceolate, mostly acute, entire, rounded or cuneate at the base, 8-15 cm. long; 



