418 POLYGONACE^E. (BUCKWHEAT FAMILY.) 



Nutt. P. aviculare, var. littorale, Ed. 2.) — Sandy sea-beach, Mass. to Virginia 

 and southward : at the north apparently only annual. (Eu.) 



16. P. ramosissimum, Michx. Stems erect or ascending, much branched 



b- (2° -4° high), rigid, many-striate ; leaves lanceolate or linear, tapering into a 

 petiole; sheaths mostly short; calyx (drying yellowish) 6-parted and with 6 or 3 



^Nv^r stamens, or 5-parted and with 4 or 5 stamens ; achenium very smooth and shining. 



— Sandy shores and banks of streams, Michigan to Illinois and southward. 

 Salt marshes, Rhode Island, Olney. — Larger leaves 2' long. 



1". P. tenue, Michx. Stemslender, upright, sparingly branched (6' -12' high), 

 sharp-angled ; leaves sessile, narrowly linear, very acute ; sheaths capillary fringed ; 

 flowers axillary and loosely gpiked on the filiform branches ; achenium smooth and 

 shining. — Dry soil, and rocky hills. 



§ 6. TIXlARIA, Meisn. Calyx 5-parted (rarely 4-parted), greenish tinged ivith 

 rose-color or white : stamens mostly 8 : styles or capitate stigmas 3 and achenium 

 3-sided (except in No. 18) : leaves heart-shaped or arrow-shaped, petioled : sheaths 

 semicylindrical. 



* Annuals, erect or somewhat climbing by the reflexed prickles which beset the angles 



of the stem and petioles: divisions of the (pale rose-colored or white) calyx not 

 keeled: bracts chaff-like. 



18. P. arif61ium, L. (Halberd-leaved Tear-thumb.) Stein grooved- 

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

 cemed (few) ; peduncles glandular-bristly ; calyx often 4-parted ; stamens G ; styles 

 2, very short; achenium lenticular (large). — Low grounds. 



19. P. sagittatum, L. (Arrow-leaved Tear-thumb.) Stem 4-angled ; 

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

 mostly 8 ; styles 3, slender ; achenium sharply 3-angled. — Low grounds : common. 



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

 armed with a line of fine and very sharp saw-toothed prickles, which cut the 

 hand drawn against them. 



* * Stems twining, not prickly : calyx with the 3 outer divisions keeled, at least in 



fruit : flowers in loose panicled racemes : bracts like the stipules. 



20. P. Convolvulus, L. (Black Bindweed.) Annual; stems twining 

 or procumbent, low, roughish, the joints naked; leaves halberd-heart-shaped, 

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

 achenium smoothish, — Cult, and waste grounds : common. (Nat. from Eu.) 



21. P. cilin6de, Michx. Perennial, minutely downy ; the sheaths fringed at 

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

 taper-pointed; racemes panicled; calyx-lobes obscurely keeled; achenium very 

 smooth and shining. — Copses and rocky hills. Climbing 3° - 9° high. 



22. P. dumet6rum, L. (Climbing False Buckwheat.) Perennial, 

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

 racemes interrupted, leafy ; the 3 outer calyx-lobes strongly keeled and in fruit 

 winged; achenium smooth and shining. (Eu.) 



Var. scandens (P. scandens, L.) has more panicled flowers, and usually 

 much broader wings to the fruiting calyx than the European. — Moist thickets. 

 Twining 8°-12° high over bushes. 



