388 polygonacejE. (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 ; interiojr 

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

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

 Eaceraes 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 the 

 albumen. Radicle slender. — Herbs, with alternate, sitnple leaves, and sheatli- 

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



§ 1. Ambltogonon. Flowers in closely-bracted spikes: stamens 7 : style 2-cleJl: 

 achenium lenticular : cotijledons incumbent : allmmen mealy. 



\. 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. Juno -Sept. — Stem 3° -5° high. Spikes 2' -3' 

 long. 



4 2. Persicaria. Flowers in closely-bracted spikes : stamens 4-8: styles 2-3, 

 or 2 - 3-cleJi : achenium 3-angled or lenticular ; cotyledons accumbent : albumen 

 horny : 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. ® — Stem 2° - 3° high. Leaves 6' - 8' long. Spikes 1 ' - 2' 

 long. 



3. P. densiflorum, Meisner. Stem stout, stnooth, 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 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' - 1 0' long. Spikes 2' - 4' long. Flowers white. 



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

 duncles roughened with short glandular hairs ; leave? short-petioled, lanceolate, 



