128 POLYGONACEAE. 



each bearing a linear-lanceolate tubercle on the back and 2 or 3 slender bristles 

 on the margins. 



Along the seashore, not common. This plant has generally been confused 

 with R. per sicari aides L. 



Rumex obtusifolius L. Bitter Dock. Stems 40-60 cm. tall, erect; leaves 

 oblong-ovate, all cordate, 15-30 cm. long; flowers long-pedicelled, in loose 

 whorls; valves of the fruit ovate, fringed with a few bristly teeth, usually but 

 one valve tubercle-bearing. 



A troublesome weed, introduced from Europe. 



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 cuneatc at the base, 8-15 cm. long; 

 petioles rather short; panicle 10-12 cm. long, the branches short, leafy-bracted; 

 valves triangular-ovate, slightly toothed, 3-4 mm. long, each bearing a large 

 oblong tubercle; akene broad, 2 mm. long. 



In wet places common., This species has been much confused with R. 

 salicifolius Weinm. 



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 22.5 mm. long, brown. 



An introduced European weed. 



Rumex conglomerates Murr. Tall and slender; leaves ovate or lanceolate, 

 the lower cordate; panicle elongated, leafy; flowers in dense whorls, the pedicels 

 very short; valves of the fruit all tubercle-bearing. 



A weed introduced from Europe. 



160. POLYGONUM. 



Annual or perennial, terrestrial or aquatic herbs, some species 

 woody; stems erect, prostrate, climbing or floating; leaves alter- 

 nate, sessile or petioled, continuous with or jointed to the cylindric 

 funnelform or 2-lobed often lacerate or fringed sheaths; flowers 

 small, perfect, green, white, pink or purple, variously clustered, 

 the clusters terminal or axillary; pedicels jointed, subtended by 

 the sheaths; calyx 4 or 5-parted or cleft, the outer segments larger 

 than the inner; stamens 3-9; stigmas capitate; akene lenticular 

 or 3-angled (rarely 4-angled), invested by or exceeding the calyx. 



Stems twining; leaves cordate. P. convolvulus. 



Stems not twining; leaves not cordate. 



Leaves small, usually narrow; stems wiry. 



Plant with woody rootstocks. P. paronycliia. 



Plant without rootstocks; mostly annuals. 

 Plants prostrate. 



Akenes not longer than the calyx. P. aviculare. 



Akenes protruding from the calyx. P. fowleri. 



Plants erect or ascending. 



Flowers in rather dense terminal bract rate 



spikes; styles nearly obsolete. P. kelloggii. 



Flowers axillary, or in loose or interrupted 

 spikes; styles present. 



