608 ORDEK 102. POLYGONACE^B. 



7. ERECTUM. Stems ascending or erect ; Ivs. larger, elliptic or oval, petiolate ; 

 fls. pedicellate; stam. mostly 5. In richer or shady soils, more common 

 westward. (P. erectum L.) 



2 P. t6nue MX. St. slender, rigid, erect, with long, simple branches, acute-angled : 

 Ivs. linear-lanceolate and linear, erect, acute ; sheaths (stipules) bristly -/ringed at 

 top ; fls. alternate, subsolitary ; ach. included. A small, slender plant, on rocky 

 soils, N. Eng. to the Mts. of Ga. and Wis. St. 6' to If high. Lvs. 1 to U' long, 

 1 to 2" wide, 3-veined, 'sessile. Fls. white. JX, Aug. 



3 P. maritimum L. Prostrate, diffusely branched, glaucous; st. striate, -with 

 very short internodes ; sheaths gibbous at base, hyaline, torn ; Ivs. fleshy, oval or 

 linear-oblong, nearly veinless ; fls. sessile ; ach. sharply angled, a little exserted, 

 smooth and shining. U Sandy shores, R. I. to S.ar. Sts. 6 to 12' long. Lvs. 

 few and small, 2 to 4" long. Fls. often crowded in leafy racemes, rose-purple, 

 green at base, 1" long. (P. avicularc, /3. glaucum, 2d edit.) 



4 P. ramossissimum MX. St. tall, erect or ascending, much branched, striate ; 

 sheaths 6-veined, at length torn ; Ivs. lance-oblong or linear, petiolate ; fls. subsoli- 

 tary, pedicellate, greenish ; ach. included, smooth but dull. CD Sandy shores of 

 streams and lakes, Mich, to 111. Much like P. aviculare, but rigidly erect, 2 to 3f, 

 with larger, petiolate Ivs. 2' long, and larger sepals, 1^-" long in fruit, green, with 

 narrow white borders. 



5 P. hirstitum Walt. HAIRY KNOT-GRASS. Hirsute, with long, spreading, tawrty 

 hairs; sheaths ciliate; Ivs. lanceolate, obtuse at base, gradually narrowed to the 

 point ; spikes 2 or 3, very slender ; bract equaling its 2 or 3 pedicels ; stamens 7 

 to 8 ; style 3-cleft ; ach. shining. Swamps, N. Car. to Fla. St. slender, root- 

 ing at base, ascending 2 to 4f. Lvs. 2 to 3' by 4 to 10", mostly smooth above, 

 sometimes dense-hairy like the stem. Fls. white. May Aug. 



6 P. hydropiperoides MX. MILD WATER-PEPPER. St. smooth; sheaths hairy, 

 bristly-ciliate, long and narrow; Ivs. linear-lanceolate, tapering to each end, 

 slightly appressed-hairy (not acrid) ; spikes 2 or more, slender, loose-flowered at 

 base; cal. glandless; stam. 8; style half-3-cleft ; ach. shining. ^Ditches and 

 wet ground, common. St. branched, 1 to 3f high. Lvs. narrowed into a short 

 petiole, not acrid. Fls. rather large, white-roseate, rather close, 4 or 5 from each 

 bract. Aug., Sept. (P. mite Pers.) 



(3. SETACEUM. Lvs. lanceolate ; stip. conspicuously fringed with long bristles. 

 In clayey soils, southward. (P. setaceum Baldw.) 



7 P. acre H. B. K. St. ascending, slender, glabrous ; sheath smoothish, fringed 

 with bristles, bearing the leaf near the base; Ivs. acrid, lanceolate, acuminate, 

 flliform, interrupted at base ; bracts truncate, 1 to 3-flowered ; ped. scarcely ex- 

 serted ; stam. 8 ; style 3-parted ; ach. 3-cornered. Wet places, ditches, com- 

 mon S. and W. Cal. greenish at base, flesh-colored, brown-dotted like the Ivs. 

 Ach. shining. Jl. Sept. (P.' punctatum Ell. P. hydropiperoides Ph.) 



8 P. Hydropiper L. WATER- PEPPER. Glabrous ; sheaths bristly-ciliate ; Ivs. 

 lanceolate, tapering to both ends, minutely, pellucid-punctate (very acrid) ; spikes 

 loose-flowered, lender, short (2 to 5') nodding; ped. exserted; cal. glandular- 

 punctate; stam. mostly 6; sty. 2 or 3-cleft; ach. flattish (rarely obtusely triangu- 

 lar), dull, minutely roughened. CD Damp waste grounds, ditches, &c., 1 to 2 f high. 

 Lvs. not more than 6" wide. Fls. green and rose-colored. Ach. black. Jl. 

 Sept. Eur. 



9 P. Carey i Olney. St. erect, hirsute, much branched; Ivs. lanceolate, with scat- 

 tered and appressed hairs; stip. scarious, tubular, truncate, hairy-ciliate ; spikes 

 axillary and terminal, on very long, nodding peduncles thickly beset with glandular 

 hairs ; stam. 6 to 8 included ; sty. 2 ; ach. orbicular-ovate, mucronate, tumid, 

 shining. CD Swamps, N. Eng. and K Y. ? Plant 3 to 5f high. Lvs. 3 to 6' by 

 6" to 1', midvein and margins hairy. Cal. greenish-purple, tinged with white, 

 minutely dotted. 



10 P. Persicaria L. St. erect ; Ivs. lanceolate, the upper surface usually marked 

 with a brownish spot; stip. fringed; spikes dense, oblong, erect; ped. smooth; stam. 

 6 ; sty. 2, half united ; ach. shining, flattened.' (J) A common species about 

 buildings, fences, wet grounds, &c. St. smooth, branched, leafy, 1 to 2f high, 



