388 rOLYGOXACE.E. (r.UCKM'IIE.VT FAMILY.) 



7. P. articulata, Moisncr. Annual ; stem much branched, slender ; loaves 

 narrowly lineiir, olituse, deciduous; sheaths truncate, pointless; racemes numer- 

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

 rose-color; se])als 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. — btcm 6'- 12' lii^^h. Leaves 4'-8'long. 

 Kaccmes l'-3' long. 



3. POLYGONUM, L. Knotweed. 



Flowers perfect. Calyx 5- (rarely 4-) parted, coroUa-likc, the lobes nearly- 

 equal, erect and unchanged in fitiit. Stamens 3-9: antiiers 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. Eadide slender. — Herbs, with alternate, simple leaves, and sheath- 

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



§ 1. Ajihlygonox. flowers in dosebj-bracted spikes: stamens 1 : style 2-cleJi: 

 achenium lenticular : coti/ledons incumbent : albumen mtctly. 



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 spihes : stamens 4-8: styles 2-3, 

 or 2-3-cleJl: aclienium 3-angled or lenticular: cotyledons accuntbent : albumen 

 horny : sheaths cylindrical, truncate. 



* Sheaths naked : style 2-cleft or 2-pa7ied : achenium lenticular. 



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

 peduncles, and caly.K sprinkled with glandular dots ; leaves lanceolate, long- 

 acuminate, petiolcd, rough on the margins and veins ; sheaths slender, nppressed ; 

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

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

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

 ward Juiy-Oct. (ij — Stem 2°-3° high. Leaves 6'-8' long. Spikes l'-2' 

 long. 



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

 branching altovc ; loaves lanceolate or oblong-lanccolatc, tapering at tl)e sum- 

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

 somewhat jmnicicd, linear, erect, dense-flowered, the peduncles minutely ghui- 

 ilular ; bra<-ts ohliiiudy truncate, obtuse, shorter than the pedicels ; stamens 

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

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

 Stem 3° -4° liigli Leaves 6'- 10' long. Spikes 2' -4' long. Flowers white. 



4 P. Pcnnsylvanicum, L Stem smomli below, the branclies and pe- 

 duncles roughened with short glandular hairs; leave,'-' shortpi liuled, lanceulute, 



