362 POLYGONAOEAE (BUCKWHEAT FAMILY) 



roughish, often marked with a dark triangular or lunar spot near the middle ; 

 spikes ovoid or short-cylindric, dense, erect, on smooth (or at least not glandular) 

 peduncles; stamens mostly 6 ; styles half 2-3-cleft ; achene gibbous-flattened or 

 sometimes triangular, smooth and shining. — Waste and damp places, very 

 common. (Nat. from Eu.) 



23. P. setjlceum Baldw. Perennial, stout, erect from a decumbent and 

 somewhat repent base, appressed-hirsute ; sheaths fringed with very long coarse 

 bristles ; inflorescence and flowers as in the next, the achenes slightly larger, 

 black, sinning. — Mo. to S. C, Fla., and Tex. (Asia.) 



24. P. hydropiperoides Michx. (Mild Water Pepper.) Perennial, not 

 acrid; stem smooth (3-9 dm. high), branching; the narrow sheaths hairy; 

 leaves narrowly lanceolate, sometimes oblong ; spikes erect, slender, sometimes 

 filiform, often interrupted at base (3-6 cm. long); flowers small, flesh-color or 

 nearly white ; sepals not dotted ; stamens 8; achene sharply triangular, smooth 

 and shining. (P. opelousanum Riddell.) — Wet places and in shallow water, 

 centr. Me., westw. and southw. Var. strig6sum Small (var. Macouni Small) 

 has the stem strigose, and is less frequent throughout our range. 



§ 4. TOVARA (Adans.) Gray. Perennials; flowers in loose naked long and 

 slender spikes; calyx rather herbaceous (greenish), unequally i-parted, 

 stamens 6 ; styles 2, distinct, rigid and persistent on the smooth lenticular 

 achene. 



25. P. virgini&num L. Almost smooth ; stem terete, upright (6-12 dm, 

 high) ; sheaths cylindrical, hairy and fringed ; leaves ovate, or the upper ovate- 

 lanceolate, taper-pointed, rounded at the base, short-petioled, rough-ciliate 

 (7-16 cm. long) ; flowers 1-3 from each bract, somewhat curved, the styles 

 deflexed in fruit, minutely hooked. — Thickets in rich soil, N. H. to Ont. , Minn. , 

 and southw. (Asia.) 



§ 5. ECHINOCATJlON Meisn. Erect or reclining annuals, armed with reflex 

 prickles on the angles of the stem, petioles, etc. ; flowers capitate or few in 

 a raceme ; leaves arrow- or halberd-shaped. 



26. P. arifblium L. (Halberd-leaved Tear-thpmb.) Stem grooved- 

 angled; leaves halberd-shaped, taper-pointed, long-petioled ; flowers somewhat 

 racemed (few); peduncles glandular-bristly; calyx often 4-parted ; stamens 6 ; 

 styles 2, very short ; achene lenticular (large). — Low grounds, N. B. to Ont., s. 

 to Ga., 0., and Mich. (Asia.) 



27. P. sagitt^tum L. (Arrow-leaved Tear-thomb.) Stem Wangled; 

 leaves arrow-shaped, short-petioled; flowers capitate ; peduncles smooth ; stamens 

 mostly 8 ; styles 3, slender ; achene sharply Z-angled. —Low grounds, common. 

 — Slender, smooth except the angles of the stem and midrib beneath, which are 

 armed with fine and very sharp saw-toothed prickles. (Asia.) 



§ 6. TINIAKIA Meisn. Twining {except dwarf var. of no. 29), unarmed; 

 leaves ovate-heart-shaped ; flowers in panieled racemes; outer calyx-lobes 

 keeled or winged. 



28. P. Conv6lvulus L. (Black Bindweed.) ^n»«a?, twining or procum- 

 bent, low, roughish, the joints naked; leaves halberd-heart-shaped, pointed; 

 flowers in small interrupted corymbose racemes ; outer calyx-lobes keeled or nar- 

 rowly winged ; achene minutely roughened, dull, black. — Cultivated and waste 

 grounds, common. (Nat. from Eu.) 



29. P. cilinbde Michx. Perennial, minutely downy ; the sheaths fringed at 

 the base with reflexed bristles ; leaves heart-shaped and slightly halberd-shaped, 

 taper-pointed ; racemes panioled ; calyx-lobes obscurely keeled ; achene very 

 smooth and shining. — Copses and rocky hills, e. Que. to nits, of N. C, w. to 

 Minn, and Athabasca. Var. erectum Peck (var. breve Peck) Is a dwarif erect 

 form with the compound racemes chiefly terminal. 



30. P. scdndens L. (Climbing False Buckwheat.) Perennial, smooth; 

 sheaths naked; leaves heart-shaped or slightly halberd-shaped, pointed; 

 I'iiceiiies intfiTuptecl, leafy ; the 3 outer calyx-lobes strongly keeled and infniit 



