POLYGONACEAE 381 



rather sharply angled, the angles mostly armed with recurved prickles : leaf-blades linear 

 or linear-lanceolate, subsagittate, 3-15 cm. long, acute or acutish, subsessile, cordate and 

 more or less clasping, almost glabrous on the upper surface, glabrous beneath except the 

 midrib which is sometimes sparsely pubescent with prickle-like hairs, glandular-ciliate : 

 ocreae 1-2 cm. long, somewhat obliquely opened and spreading at the summit, naked, very 

 thin, fringed around the base with small recurved prickles : inflorescence dichotomous, 

 more or less compound, the ultimate divisions ending in clusters or spicate racemes : 

 peduncles glandular : racemes few-flowered : ocreolae 1 mm. long, ciliate : calyx rose- 

 colored, campanulate : sepals 2-3 mm. long, ovate-oblong, obtuse : stamens 5 : achenes 

 varying from broadly ovoid to obovoid, 3-angled, dark brown, smooth and shining, the 

 angles obtuse. [Polyyonum Beyrichianum Cham. & Schlecht.] 



In low ground, Louisiana to Texas, Mexico and Brazil. Also in the West Indies. 



2. Tracaulon sagittatum (L.) Small. Annual, bright green or parts tinged with 

 red. Stem decumbent, ascending or reclining, 3-15 dm. long, four-angled and finely chan- 

 neled, armed on the angles with sharp recurved prickles, by which the plant climbs : leaf- 

 blades lanceolate or oblong, sagittate, 1-12 cm. long, cordate, the lower ones long-petioled, 

 the upper short-petioled, lighter green beneath than above, slightly roughened on the edge 

 by small prickles : ocreae funnelform, very oblique, 0.5-1 cm. long, acute, eciliate : ocre- 

 olae bract-like, lanceolate, 3-5 mm. long : calyx white, green or red, 4 mm. long : sepals 

 oblong, obtuse : stamens 8 : achenes 3-angled, 3-3.5 mm. long, ovoid, sharp-tipped, black 

 or brownish, smooth and shining. \_Polygonum sagittatum L.] 



In swamps, Newfoundland to Saskatchewan, Florida and Texas. 



3. Tracaulon arifolium (L. ) Raf. Perennial or annual, bright green. Stem as- 

 cending and reclining, 2-9 dm. long, nearly simple or much branched, armed on the four 

 angles with stout recurved prickles, the peduncles and pedicels glandular or pubescent : 

 leaf-blades broadly hastate, 2-18 cm. long, cordate or subcordate, pubescent or glabrous on the 

 lower surface, the basal lobes acuminate : ocreae funnelform, oblique, 0.5-1 cm. long, fringed 

 at the summit with short bristles and at the base with short bristle-like prickles : racemes 

 1-2 cm. long, somewhat leafy, interrupted : ocreolae funnelform, oblique, 2mm. long : calyx 

 greenish or rose-colored : sepals 4, oblong, obtuse : stamens 8 : achenes lenticular, 4 mm. 

 long, obovoid or oblong-ovoid, dark brown or variegated, very smooth and shining. \_Poly- 

 gonum arifolium L. ] 



In swamps, New Brunswick to Minnesota and South Carolina. 



11. TINIARIA Reichenb. 



Annual or perennial often scurfy unarmed twining vines. Leaves alternate : blades 

 membranous or leathery, cordate or hastate. Ocreae oblique, naked or fringed at the top 

 or the base. Racemes loosely flowered, axillary or terminal, often paniculate, leafy- 

 bracted or naked. Sepals 5, green, white or yellowish, 2 exterior, 2 interior and 1 with 

 one edge interior and one edge exterior, this sepal and the two outer keeled or strongly 

 and conspicuously winged. Pedicels slender, reflexed and articulated. Stamens 8, in- 

 cluded : filaments short, converging. Styles 3, short or almost wanting, distinct or rarely 

 united. Achenes 3-angled, dark brown or black, included, smooth and shining or granu- 

 lar and dull. Endosperm horny. Cotyledons accumbent. The plants flower in the sum- 

 mer and fall. 



Outer sepals keeled at maturity. 



Inflorescence consisting mostly of axillary and terminal clusters and simple ra- 

 cemes : achene granular. 1. T. Convolvulus. 

 Inflorescence consisting mostly of axillary and terminal panicled racemes : achene 



smooth. 2. T. cilinodis. 



Outer sepals developing conspicuous wings. 

 Sepal-wings not incised. 



Mature calyx 6-8 mm. long ; wings flat. 3. T. dumetorum. 



Mature calyx 10-12 mm. long ; wings crisped. 4. T. scandens. 



Sepal-wings incised. 5. T. cristata. 



1. Tiniaria Convdlvulus (L.) Webb. & Moq. Annual, scurfy, dull green or pale 

 green. Stem prostrate or twining, 1-12 dm. long, branched from near the base, the inter- 

 nodes of the older branches greatly elongating : leaf-blades broadly or narrowly ovate or 

 ovate-sagittate, the uppermost nearly sagittate, 1.5-6 cm. long, acuminate at the apex, cor- 

 date or truncate at the base, somewhat undulate and crisped : ocreae oblique, 2-4 mm. long, 

 acute, rough on the edges : flowers several in a cluster : racemes simple, 1-6 cm. long, 

 loosely flowered, interrupted : calyx green, at length 3.5-4 mm. long, closely investing the 

 fruit : sepals oblong, obtuse, the three outer ones keeled : stamens 8 : achenes 3-angled, 



