388 POLYGONACE^E. (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. 



1 . AMBLYGONON. Flowers in closely-bracted spikes : stamens 7 : style 2-cleft : 

 achenium lenticular : cotyledons incumbent : albumen mealy. 



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

 nate, petioled; 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 3-angled or lenticular: cotyledons accumbent: albumen 

 horny : sheaths cylindrical, truncate. 



* Sheaths naked: 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 r Oct. Stem 2 - 3 high. Leaves 6' - 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 panicled, 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 

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

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



