372 BIETHWORT FAMILY. 



P. sagittitum, Linn. Low grounds ; leaves arrow-shaped, short-peti- 

 oled ; the peduncles naked ; stamens mostly 8 ; styles 3 ; akene sharply 

 5-angled. 



-- *- BLACK BINDWEED. Stems twining, not prickly ; flowers whitish, in 

 loose, panicled racemes; three outermost of the 5 divisions of the calyx 

 keeled or crested, at least in fruit; stamens 8; styles 3; akenes trian- 

 gular. 



P. Convdlvulus, Linn. BLACK BINDWEED. Low twining or spreading 

 weed from Eu., in cultivated fields, etc.; smoothish, with heart-shaped 

 and almost halberd-shaped leaves, and very small flowers. 



P. cilin6de, Michx. Rocky shady places ; tall-twining, rather downy ; 

 a ring of reflexed bristles at the joints ; leaves angled-heart-shaped ; outer 

 sepals hardly keeled. 2i 



P. dumet6rum, Linn., var. scclndens, Gray. CLIMBING FALSE BUCK- 

 WHEAT. Moist thickets ; tall-twining, 6-12, smooth ; joints naked ; 

 leaves heart-shaped or approaching halberd-shaped ; panicles leafy ; outer 

 sepals strongly keeled and in fruit irregularly winged. 2Z 



4. FAGOPYRUM, BUCKWHEAT. (The botanical name, from the 

 Greek, and the popular name, from the German, both denote Beech- 

 wheat, the grain resembling a diminutive beech-nut.) Cult, from N. 

 Asia, for the flour of its grain ; flowers summer. (Lessons, Fig. 

 342, 344.) 



F. esculentum, Moench. COMMON B. Nearly smooth ; leaves triangular- 

 heart-shaped, inclining to halberd-shaped or arrow-shaped, on long 

 petioles ; sheaths half-cylindrical ; flowers white or nearly so, in corym- 

 bose panicles ; stamens 8, with as many honey-bearing glands interposed ; 

 styles 3 ; acutely triangular akene large. 



F. Tatdr/cum,Gsertii. TARTARY or INDIAN WHEAT. Cult, for flour ; like 

 the other, but flowers smaller and tinged with yellowish ; grain smaller, 

 with its less acute angles wavy, dull, and roughish. 



5. FOLYGONELLA. (Diminutive of Polygonum.) 



P. articul&ta, Meisn. A slender little plant, bushy-branching, 4'-12' 

 high ; leaves small and thread-like or at length none ; the sheaths trun- 

 cate, naked, rigid ; many-jointed raceme with a single flower under each 

 bract ; flowers rose-colored, nodding ; stamens 8 ; akene triangular. 

 Sandy dry soils, on the coast, Me., S. , and along the Great Lakes. 



XCVH. ARISTOLOCHIACE^l, BIRTHWORT FAMILY. 



Known from all other apetalous orders by the numerous 

 ovules and seeds in a 6-celled ovary, to which the lower part 

 of the lurid calyx is adherent, the latter mostly 3-lobed, the 

 stamens generally 6 or 12, and more or less united with the 

 style. Anthers adnate and turned outwards. .Calyx dull- 

 colored, valvate in the bud. Leaves petioled, usually heart- 

 shaped, not serrate. Flowers solitary, perfect, commonly 

 large and odd. Bitter, tonic or stimulant, sometimes aro- 

 matic plants. 



