P0LTG0XACEJ2. (BUCKWHEAT FAMILY.) 375 



nium lenticular: annuals, with heart-shaped or arrow-shaped petioled leaves: 

 sheaths semtcylindrical. 



* Steins flaccid, not twining, but somewhat climbing or supported on other plants 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. 



16. P. arifoliuui, L. (Halberd-leaved Teas-thumb.) Stem grooved- 

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

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

 styles 2, very short; fruit lenticular (large). — Low grounds. Aug. 



17. P. sagittiituui, L. (Arrow-leaved Tear-thumb.) Stem 4- 



angled ; leaves arrow-shaped, short-pit ioltd ; flowers capitate; peduncles smooth; 

 stamens mostly 8 ; styles 3, slender ; fruit sharply 3-angled. — Low grounds ; com- 

 mon. July- Sept. — 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 (greenish tinged with white or i-ose-color) with 

 the 3 outer divisions keeled, at least in fruit : flowers in loose panicled racemes: 

 bracts like the. stipules. 



18. P. Convolvulus, L. (Black Bindweed.) Stems twining or pro- 

 cumbent (l°-2° long), roughish, the joints naked; leaves halberd-heart-shaped, 

 pointed ; flowers in small interrupted corymbose racemes ; ouU r calyx-lobt s keeled; 

 fruit smootbish. — Cultivated and waste grounds ; common. Juiy, Aug. (Nat. 

 from Eu.) 



19. P. cilisidde, Michx. M inutely 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; fruit very smooth and 

 shining. — Copses and rocky hills ; New England and Fenn. to "Wisconsin, and 

 northward. July - Sept. — Stems climbing 3° - 9° high. 



20. P. duutetoriBiii, L. (Climbing False Buckwheat.) Smooth; 

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

 interrupted, leafy; the 3 outer calyx-lubes strongly keeled and in fruit winged, the 

 wings often broad, sometimes very narrow ; fruit smooth and shining. (F. scan- 

 dens, L.) — Moist thickets; common. Aug. — Stems twining 8°-12° high 

 over bushes. (Eu.) 



2. FAGOP^BUM, Tourn. Buckwheat. 



Calyx petal-like, equally 5-partcd, withering and nearly unchanged in fruit. 

 Stamens 8. Styles 3 : stigmas capitate. Aehenium 3-sidcd, longer than the 

 calyx. Embryo large, in the centre of the albumen which it divides into 2 parts, 

 with very broad and foliaceous plaited and twisted cotyledons. — Annuals, witb 

 triangular-heart-shaped or halberd-shaped leaves, semicylindrical sheaths, and 

 corymbose racemes or panicles of white flowers, often tinged with green or rose- 

 color. (Name (prjyos, the beech, and nvpos, wheat, from the shape of the grain 

 being that of the beech-nut ; whence also the English name .Buckwheat, from 

 tbe German JiJucfoe, beech.) 



