418 POLTGONACE^. (BUCKWIIKAT FAMILY.) 



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

 and southward : at the north apparently only annual. (P^u.) 



1 6. P. ramosissimum, Alichx. Stems erect or uscending, much branched 

 (2°-4° hi^h), riyid, iiiiiny-striatc ; leaves lanceolate or linear, taperiii;/ into a 

 petiole; sheidlis iiwstlij short; calyx (drying yellowish) 6-parted and with 6 or 3 

 stamens, or 5-partcd and with 4 or 5 btumens ; achmium very smooth and shoiiiu/. 



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

 Salt marshes, Kliodc Island, Oliie;j. — Larger leaves 2' long. 



17. P. t6nue, Mich.x. SlemsUnder,\tpri(jht, sfKirimjIij branched (a' ~\2' hv^h), 

 sharp-angled ; leaves sessile, narrowlj limar, very acute ; sheaths capillary fringed ; 

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

 shinimj. — Dry soil, and rocky hills. 



§ 6. TINIARIA, Meisn. Calyx 5-parled (rarely 4-parted), (jreenish tinrjed with 

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

 3-sided {except in No. 18) : leaves heart-shaped or arrow-shaped, pet ioltd : sheaths 

 sem icylindrica I. 



* Annuals, erect or somcichut climbing hy the rrjlcrid prickles which beset the angles 



of the stem and jietioles: divisions oj' the (pale rose-colored or white) calyx iiot 

 keeled: bracts chaff-like. 



18. P. arifolium, L. (IIalberd-leaved TEAR-muMn.) Stem grooved- 

 angled ; haves halberd -shaped, taper-pointed, long-petiohd ; flowers somewhat ra- 

 cemed (few) ; peduncles glandular-bristly ; calyx often 4-partcd ; stamens C ; styles 

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



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

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

 mostly 8; s/yes 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 : Jlowers in loose paniclcd racemes : bracts like the stipules. 



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

 or procumbent, low, roughish, the joints naked; leaves halbcrd-hcart-shaped, 

 jiointed ; flowers in small interrupted corymbose racemes ; outer calyx-loins 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 paniclcd; calyx-lol>es obscurely keeled; achenium very 

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



22. P. dumetbrum, L. (Climbing False Buckwheat.) Pirenniid, 

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

 racemes interrupted, leafy; the 3 outer ralyx-ioUs strongly keeled and in fruit 

 winged; achenium smooth and shining. (Eu.) 



Var. seandens (P. scanden.s, L.) has more paniclcd flowers, and usually 

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

 Twining 8° -12° high over bushes. 



