474 ex. POLYGONACEiE. Polygonum. 



§ 1. AvicuLARiA. Floxcers axillary. Stamens 5—8. Stigmas 3. 



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



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

 flowers subsessile. — ® A common weed in fields, highways and door-yards, U. 

 S. and Brit. Am. Stems slender, i— lif long, striate, smooth, branching, 

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

 except the edges, ^—V long and \ as wide. Flowers reddish, smaTl, 2 or 3 

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



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

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



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



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

 cellate ; sla. mostly 5.— 7|. 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^f 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. Muhl.) Slender Knot-grass. 



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

 acuminate ; slip, tubular, villose at top ; fis. alternate, subsolitary, axillar}-. — 

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

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



§ 2. Persicaria. Spikes terminal or axillary. 



4. P. PUNCTATiiM. 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; sly. 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 4 as wide. Flowers green, tinged with 

 purple and white. Aug., Sept. 



5. P. MITE. Pers. (P. h)'dropiperoides. Michx. P. barbatum. Walt.) 

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



hairy above; lvs. narrow, lanceolate, subhirsute; slip, 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—4' long, \ 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. 



6. P. Pennsylvaniclm. Pennsylvanian Knot-grass. 



St. smooth, tumid at the joints; lvs. lanceolate, petiolate; slip, 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. Jl. 



7. P. LAPATHiFOLiL-M. (P. incamatum. Ell.) 



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

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



6 ; 5/7/. 2. X A rare species in swamps and ditches, N. Y. to Ga. Stem 2 — 4f 



high." Leaves 3—5' long, j— i as wide. Petioles i— i' long. Flowers small, 

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



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



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

 dense, oblong, erect ; pcd. smooth ; sta. 6 ; sty. 2, half united.—® A common 

 species about building.s, 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 nv ! JI'j. Flowers rose-colored, in short, dense, terminal spikes. Jn., Aug. ^ 



