420 roLYGOXACE.E. (buckwiikat family.) 



hcfirt-shapcfl nearly entire valves bearing a small grain, or its midrib tbickened 

 at tlic base, was found spontaneous at Aniberst, Mass., by Piof. Tuvkenmin, in 

 tbc form witli undulate leaves, K. oricntaiis, Bcnih. (Adv. from Eu.) 



2. B,. longif6lils, DC. (R. donie'sticus, Ilmtm., and too near R. aquat- 

 icus, L.), known by tbc rounded somewbat beart-sbaped valves all witbout a 

 grain, — i.s indigenou.s at tlie nortbwest, pcrbaps in Nortbern Wisconsin. (Eu.) 



■*- Valves (amuller) one or more of them conspicuousl y f/rain-benring. 

 ■*-*■ Intlirjenoiis: /fares not wavy, none htart-shaped, except the lowest of No. 6. 



3. R, orbieul^tus, Gray. (Great Water-Dock.) Tall and stout 

 (5°-G° lii-li) ; rateinus upriylit in a large compound panicle, nearly leafless ; 

 ■wborls crowded ; pedicels cctpillnri/, noddimi, about twice the lemjth of the fruiting 

 calyx ; the vidves orbicular or round-orate, very obtuse, obscurely beart-sbaiwd at 

 base, membranaceous, finely reticulated, entire or repand-denticnlate (2" -3" 

 broad), all grain-bearing; leaves oblong-lanceolate, rather acute at botb ends, 

 transvei-sely veined, and witb obscurely erose-crenulatc margins (tbe lowest, in- 

 cluding the petiole, l°-2° long, the middle rarely truncate or obscurely cordate 

 at base). (R. Ilydrolapatbum, var. 1 Americanus, Ed. 2. R. Britannica, Pursh ? 

 Tiiijelow, Toff. F\. N. Y. R. aqua'ticus, Pursh ?) — Wet places : rather common 

 northward. — Root yellow. Leaves occasionally abruptly contracted a little be- 

 low the enlarging apex. Valves very much rounder, thinner, larger in propor- 

 tion to the grain, and more reticulated than in tbe Eurojican R. Ilydrolapatbum, 

 resembling those of R. longifolius except in bearing a conspicuous grain. 



4. R. Britannica, L. (Pale Dock.) Rather tall (2°-6° high); ra- 

 cemes spike-like and panicled, nearly leafless; whorls crowded ; pedicels noddiurj, 

 shorter than the fruiting calyx ; the valves broadly ovate or obscurely heart-shaped, 

 obtuse or acutish, entire, membranaceous, loosely reticulated (about 2" broad), 

 one witb a conspicuous grain, the others witb a small grain or tbickened midrib, 

 or naked ; leaves ovate-lanceolate or oblong-lanceolate, acute, pale, thiekish. obscurely 

 veiny (those of the stem 3' - 6' long, contracted at base into a short petiole), none 

 heart shaped. (R. Claytonii, Campdera, which name is to be adopted if we 

 reject that inconsiderately assigned by Linnajus, who transferred the obscure 

 Herba Britannica of the old writers to a Virginian species. R. xanthorhizus, 

 Uoffmansegg, ex Meisner. R. altissimus, Wood.) — Moist grounds, New York 

 to Illinois and southward. 



5. B. salicifblius, Weinmann. (White Dock.) Rather low (l°-3° 

 high); root white; leaves narrowly or linear-lanceolate, or the lowest oblong; 

 whorls much crowded ; pedicels much shorter than the fruiting calyx; valves deltoid- 

 ovate, obtnsisb or acutish (about 1 j'' long), one, two or sometimes all three with 

 a consj)icuous often very large grain : otherwise nearly as in the preceding. (R. 

 pallidus, Bigeiow.) — Salt marshes, coast of New England ; also far westward 

 and northward. 



6. R. vertieill^tUS, L. (Swamp Dock.) Rather tall (3°-:>° high); 

 racemes nearly leafless, elongated, loose ; tbe whorls crowded or the lower ones 

 distant; fruit-bearing pedicels slender, club-shaped, abruptly reflexed, 3-4 times 

 lunger than the fruiting calyx ; the valves dilated-rhomboid, obtusely somewhat pointed, 

 strongly rugose-reticulated, each bearing a very large grain ; leaves lanceolate or 



