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 arif olium ( 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 arif olium 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 waiting, 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 Convolvulus (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, 



