390 POLYGONACEJE. (BUCKWHEAT FAMILY.) 
17. P. sagpittatum, L. (Arrow-leaved Tear-thcmb.) 
Stem 4-angled ; leaves arrow-shaped , short-petioled ; flowers capitate ; 
peduncles smooth ; stamens mostly 8; styles 3, slender; fruit sharply 
3-angled. — Low grounds, common. July - Sept. — Slender, smooth 
except the angles of the stem and midrib beneath, which are closely 
beset with a line of fine and very sharp saw-toothed prickles, which 
cut the hand drawn against them : leaves 1* — long. 
* * Stems twining , not prickly: calyx {jgreenish tinged with white or 
rose-color) with the 3 outer divisions keeled, at least in fruit : fiowcrs 
in loose panided racemes : bracts like the stipules. 
18. P. Convolvulus, L. (Black Bindweed.) Stems twin- 
ing or procumbent, roughish , the joints naked ; leaves halbert-heart¬ 
shaped, pointed, flowers in small interrupted racemes; outer calyx- 
lobes keeled ; fruit smoothish. — Cultivated and waste grounds, com¬ 
mon : probably introduced. July. — A low weed with inconspicu¬ 
ous flowers. 
19* P* Cilindde, Michx. (Fringe-jointed False Buck¬ 
wheat.) Minutely downy; the sheaths fringed at the base with re- 
flexed bristles; leaves heart-shaped and slightly halbert-shaped, taper- 
pointed; racemes panicled; calyx-lobes obscurely keeled; fruit very 
smooth and shining. — Copses and rocky hills, common northward. 
July - Sept. —■ Stems climbing 3° - 9° high. 
20. P. dumetorum, L. (Climbing False Buckwheat.) 
Smooth; sheaths naked ; leaves heart-shaped or slightly halbert-shap¬ 
ed, pointed; racemes interrupted, leafy ; the 3 outer calyx-lobes strong - 
ly keeled and in fruit winged; fruit smooth and shining. (P. scan- 
dens, L.) — Moist thickets, twining 8P- 12P high over bushes. Aug. 
2. FAGOPYRUM, Tourn. Buckwheat. 
Calyx petal-like, equally 5-parted, withering and nearly un¬ 
changed in fruit. Stamens 8. Styles 3 : stigmas capitate. Ache- 
mum 3-sided, 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, with triangu¬ 
lar-heart-shaped or halbert-shaped leaves, semicylindrical sheaths, 
and corymbose racemes or panicles of white flowers, often tinged 
with green or rose-color. (Name (prjyds, the beech , and irvpos, 
wheat, from the shape of the grain being that of the beech-nut; 
whence also the English name JftzuAwheat, from the German 
aSuu&e, beech.) 
®SCUlentUin, Mcench. (Buckwheat.) Smoothish. 
flower with 8 honey-bearing yellow glands interposed between the 
