383 TOLYGONACEiE. (BUCKWHEAT FAMILY.) 



7. P. articillata, Meisner. Annual ; stem much branched, slender ; loaves 

 narrowly linear, obtuse, deciduous; sheaths truncate, pointless; racemes numer- 

 ous, erect, slender ; bracts truncate, open, the lowest ones pointed ; flowers bright 

 rose-color ; sepals oval or roundish, nearly equal, unchanged in fruit ; interior 

 filaments rhombic-ovate at the base. (Polygonum artieulatum, L.) — Dry sandy 

 soil, Georgia, and northward. Aug. — Stem 6'- 12' high. Leaves 4'-8'long. 

 Racemes I' -3' long. 



3. POLYGONUM, L. Knotweed. 



Flowers perfect. Calyx 5- (rarely 4-) parted, corolla-like, the lobes nearly 

 equal, erect and unchanged in fruit. Stamens 3 - 9 : anthers roundish. Styles 

 2-3, distinct or partly united : stigmas entire. Achenium 3-angled or lenticu- 

 lar, enclosed in the persistent calyx. Embryo curved on the outside of l!.e 

 albumen. Radicle slender. — Herbs, with alternate, simple leaves, and sheath- 

 ing stipules. Flowers commonly white or rose-color, variously disposed. 



§ I. Amblyogonon. Flowers in closely-bractcd sj/ikes : stamens 7 : style 2-chj't: 

 achenium lenticular : cotyledons incumbent : albumen mealy. 



1. P. orientate, L. Hairy; stem tall, branching; leaves ovate, acumi- 

 nate 1 , petioled; sheaths loose, salver-form; spikes panieled, cylindrical, dense, 

 nodding ; bracts ovate ; flowers large, bright rose-color. — Around dwellings. 

 escaped from cultivation. June -Sept. — Stem 3° -5° high. Spikes 2' -3' 

 long. 



§ 2. Persic Am a. Flowers in close! y-bractcd spikes : stamens 4-8: styles 2-3, 

 or 2-3-cleft: achenium 3-anyled or lenticular: cotyledons decumbent: albumen 

 homy : sheaths cylindrical, truncate. 



* Sheaths naked: style 2-cleft or 2-parled : achenium lenticular. 



2. P. incarnatum, Ell. Stem smooth below, the summit of the branches, 

 peduncles, and calyx sprinkled with glandular dots ; leaves lanceolate, long- 

 acuminate, petioled, rough on the margins and veins ; sheaths slender, appressed ; 

 spikes racemed, linear, nodding ; bracts spreading, acute, longer than the pedi- 

 cels ; flowers small, flesh-color. Stamens 6 , style 2-parted ; achenium ovate, 

 with the sides concave. — Ponds, ditches, &c., South Carolina, and west- 

 ward July- Oct. (l) — Stem 2° -3° high. Leaves G'- 8' long. Spikes 1'- 2* 

 long. 



3. P. densiflorum, Meisner. Stem stout, smooth, tumid at the joints, 

 branching above; leaves lanceolate or oblong-lanceolate, tapering at the sum- 

 mit, but rather obtuse, rough on the margins and veins ; spikes racemed or 

 somewhat panieled, linear, erect, dense-flowered, the peduncles minutely glan- 

 dular; bracts obliquely truncate, obtuse, shorter than the pedicels; stamens 

 mostly 6; style 2-cleft; achenium round-ovate, black and shining, with the 

 Bides convex — Muddy banks, Florida, and westward. Sept. and Oct. (J) — 

 Stem .", -4 high- Leaves G' - 10' long. Spikes 2' -4' long. Flowers white. 



4. P. Pennsylvanicum, L Stem smooth below, the branches and pe- 

 duncles roughened with short glandular hairs; leaves short-pctiolcd, lanceolate, 



