BUCKWHKAT FAMILY. 289 



P. Hydrdpiper, Common S. or Water Pepper. Low or wet grounds 

 N. : l°-2° high; leaves oblong-lanceolate; spikes nodding, mostly short; 

 flowers greenish-white ; stamens 6 ; akene either flat or obtusely triangular. (T) 



* « * » Leaves heart-shaped or arrovishaped, petiokd : sheaths half^cylindrical. 

 ■I- Tear-thomb. Steins with spreading brandies, the.angles and petioles armed 



with sharp refkxed mickles, bi/ wfiinh the plant is ennb/ed almost to climb : 

 flowers in peduncled heads or short racemes~white or fl,esh-color. (T) 



P. arifdlium. Low grounds : leaves halberd-shaped, long-petipled ; the 

 peduncles glandalar-bristly ; stamens 6 ; styles 2 ; akene lenticular. 



P. sagltt&tuiu. Low grounds : leaves arrow-shaped, short-petioled ; the 

 peduncles naked ; stamens mostly 8 ; styles 3 ; akene sharply S-arigled. 



■1- -I- Black Bindweed. Stems twining, not pnckly : flowirs whitish, in loose 

 panicled racemes : three outermost of the 5 divisions of tlie cahjoi: heeled or 

 ci'ested, at least infniit : stajnens 8 : stifles 3 : akenes triangular. 



P. Convdlvulus. Low twining or spreading weed from Eu., in culti- 

 vated fields, &c., : sraoothish, with heart-shaped and almost halberd^shaped 

 leaves, and very small flowers. ' ® ■ 



P. cilinbde. Rocky shady places : tall-tivining, rather downy, a ring of 

 reflexed bristles at the joints ; leaves angled-heart-shaped ; outer sepals hardly 

 keeled. % , 



P. dumetdrum. Climbing Fai-se Buckwheat. Moist thickets : tall- 

 twining, smooth; joints naked; leaves heart-shaped or approaching halberd- 

 shaped ; panicles leafy ; outer sepals strongly keeled and in fruit UTegularly 

 winged. % 



2. PAGOPYRITM, 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 : fl. summer. ® 



F. eseul6ntum, 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 corymbose panicles ; stamens 8, 

 with as many honey-bearing glands interposed ; styles 3 ; acutely triangular 

 akene large, 



F. tartaricum, Taktary or Indian Wheat. Cult, for flour on our 

 N. E. frontiers and N. : like the other, but flowers smaller and tiiiged with 

 yellowish ;. grain half the size, with its Ig^ acute angles wavy. 



3. RHEUM, RHUBARB. (Name said to come from the Greek, and to 

 refer to the. purgative properties of the root ; that .of several species, "of N. 

 Asia, yield officinal rhubarb.) 2/ 



R. Rhaponticum, Garden R. or Pie^plant ; the large fleshy stalks of 

 the ample rounded leaves, filled with pleasantly acid juice, cooked in spring as 

 a substitute for fruit ; flowers white, in late spring. , 



4. RUMEX, POCK, SORREL. (Old Latin name.) The three enlarged 

 sepals which cover the fruit are called valves. Flowers greenish, in whorls 

 on the branches, forming panicledj-acemes or interi'upted spikes. ■ 



§ I. Dock. Herbage bitter :. flowers- perfect or parthj moncecious, in summer. 



* In marshes : stem erect, stout : leaves lanceolate, or lance-oblong, fliat, not wavi/ : 



valves entire or ohscureli/ wavg-loothed in the first species. ^, 

 R. orbieulitus, Great Water Dock. Common N. : 5° -6° high; 

 leaves Often l°-2° long; flowers nodding on slender pedicels; the valves 

 round-ovate or almost orbicular, thin, finely reticulated, nearly {' wide, each 

 hearing a s^-ain. ' 



' . R. Britanniea, Pai-e D. Commoner S.^ 2° -6° high; pedicels nodding, 

 shorter than the fruiting calyx, which has broadly ovate loosely reticulated 

 valves, one with a large grain, the others commonly naked ; root yellow. 



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