474 ex. POLYGONACE.^. Polygonum. 



' § 1. AvicuLARiA. Flowers axillary. Stainens 5 — 8. Stigmas 3. 



1. P. AVicuLARE. Bird Polygouuvi or Knot-grass. 



St. procumbent ; Ivs. elliptical-lanceolate, rough-edged, acute, sessile ; 

 Jlowers subsessile. — (T) A common weed in lields, highways and door-yards, U. 

 S. and Brit. Am. Stems slender, \ — l^f long, striate, smooth, branching, 

 with short, white, torn, remotely veined stipules at the joints. Leaves smooth 

 except the edges, ^ — 1' long and i as wide. Flowers reddish, small, 2 or 3 

 together in the axils of the leaves, appearing all summer. 



/?. glaucum. (P. glaucum. Nutt.) Lvs. fleshy, glaucous, revolute on the mar- 

 gin. — Grows on the sea-coast. Long Island. 



2. P. ERECTDM. (P. aviculare. /?. latifolium. Michx.) Erect Knot-grass. 



St. mostly erect, branched; lvs. smooth, broadly oval, petiolate; Jis. pedi- 

 cellate ; sta. mostly 5. — % Western and Mid. States and Brit. Am. A species 

 remarkably distinct in appearance from the last, in similar situations, but sel- 

 dom growing with it. Stem 1 — 2^1' high, branched, smooth. Leaves 1 — 2' 

 long and about J as wide, rather obtuse, the petioles — i' long. Flowers 2 — 3 

 together, pedicellate, in the axils of the leaves, yellowish. Jn. — Sept. 



3. P. TENUE, Michx, (P. linifolium. MiM.) Slender Knot-grass. 



St. slender, erect, branched, acute-angled ; lvs. linear-lanceolate, erect, 

 acuminate ; stip. tubular, villose at top ; Jis. alternate, subsolitary, axillary. — 

 A small, slender plant, on rocky soils, N. Eng., Mid. States, Stem | — If high. 

 Leaves 1 — 1^' long, 1 — 2" wide, 3-veined, sessile. Flowers white, Jl., Aug, 



§ 2. Persicaria. Spikes terminal or axillary. 



4. P, PUNCTATUM, Ell. (P, Hydropiper, Michx. not of Linn.') Water 

 Pepper. — St. branched, often decumbent at base ; lvs. lanceolate, punctate 



with pellucid dots, waved and scabrous on the margin ; spike loose, interrupted, 

 drooping ; sta. 6 — 8 ; sty. 2, united half way up. — ® Can. to Flor. A plant 

 well known for its acrid taste, growing in ditches, low grounds, among rub- 

 bish, &c. Stem smooth, swelling above the joints, 2f high, and, like the 

 leaves, sprinkled with glandular dots, in which the acrimony is said to reside. 

 Leaves 2 — 3' long and not more than \ as wide. Flowers green, tinged with 

 purple and white. Aug., Sept. 



5. P. MITE, Pers, (P. hydropiperoides, Michx. P, barbatum, Walt.) 

 Mild or Tasteless Knot-grass. — St. mostly decumbent at base, erect and 



hairy above ; lvs. narrow, lanceolate, subhirs'ute ; stip. hirsute, long-ciliate ; 

 spikes linear ; bracts ciliate, subimbricate ; sta. 8 ; sty. 3. — Ditches and ponds, 

 Can. to Car. and Tenn, Stem a foot or more high. Leaves 2 — i' long, i as wide, 

 sessile. Spikes several, crowded near the summit of the stem, composed of small 

 fascicles of reddish flowers, Jl,, Aug, See also Addenda, p. 638, 



G, P, Pennsylvanicum, Pennsylvanian Knot-grass. 



St. smooth, tumid at the joints; lvs. lanceolate, petiolate; stip. glabrous, 

 not ciliate ; spikes oblong, crowded ; ped. hispid ; sta. 8; sty. 2 or 1. — ® Mar- 

 gins of ponds and ditches, N. H. to Car. Stem geniculate, branched above, 

 2 — 4f high. Leaves 3 — 5' long, \ as wide, slightly scabrous. Spikes short and 

 dense, large, and somewhat nodding. Flowers large, rose-colored, pedicellate, J 1. 



7, P, LAPATHiFOLiQM. (P. iucamatum. Ell.) 



St. geniculate, smooth ; lvs. ovate-lanceolate, petiolate, often hoary 

 beneath ; spikes numerous, rather crowded, erect, on scabrous peduncles ; sta. 

 6; sty. 2. — A rare species in swamps and ditches, N. Y. to Ga. Stem 2 — 4f 

 high. Leaves 3 — 5' long, \ — h as wide. Petioles i — ^' long. Flowers small, 

 white, or tinged with red, in numerous, panicled spikes. Aug, 



8. P. PERSICARIA. Ladies' Thumb. Spotted Knot-imed. 



St. erect; lvs. lanceolate, the upper surface spotted; stip. fringed; spikes 

 dense, oblong, erect ; ped. smooth ; sta. 6 ; sty. 2, half tmited. — A common 

 species about buildings, fences, wet grounds, &c. Stem smooth, branched, 

 leafy, 1 — 2f high, often colored. Leaves 2 — 4' long, i as wide, entire, short- 

 stalked, acuminate, generally marked with a brownish, heart-shaped spot near 

 the middle. Flowers rose-colored, in short, dense, terminal spikes, Jn., Aug. ^ 



