388 poltgoxacejE. (buckwheat family.) 



7. P. articulata, Meisner. Annual ; stem much branched, slender ; leaves 

 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 articulatum, L.) — Dry sandy 

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

 Racemes l'-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 the 

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

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



<j 1. Amblyogonon. Flowers in closeIi/-bracted spikes: stamens 7 : style 2-cleft: 

 (ichenhun lenticular : cotyledons incumbent : ullnnnen mealy. 



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

 nate, petiolcd ; sheaths loose, salver-form ; spikes panicled, 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. Persicaria. Flowers in closely-bracted spikes : stamens 4-8: styles 2-3, 

 or 2 - 3-cleft : achenium S-anrjled or lenticular : cotyledons accumbent : albumen 

 horny : sheaths cylindrical, truncate. 



* Sheaths nuked: style 2-cleft or 2-parted: 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. Q) — Stem 2° -3° high. Leaves 6' - 8' long. Spikes l'-2' 

 long. 



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

 branching above; leaves lanceolate or oblong-laiiceolate, tai>ering at the sum- 

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

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

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

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

 sides convex — Muddy banks, Florida, and westward. Sept. and Oct. ® — 

 Stem 3° -4° high Leaves 6'- 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 ; leave? short-pctioled, lanceolate, 



