6 P. hydropiperoides Mx. Mild Water-pepper. St. smooth; sheaths hairy, bristly-ciliate, long and narrow; lvs. linear-lanceolate, tapering to each end, slightly appressed-hairy (not acrid); spikes 2 or more, slender, loose-flowered at base; cat. 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.)
β. 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; lvs. acrid, lanceolate, acuminate, filiform, interrupted at base; bracts truncate, 1 to 3-flowered; ped. scarcely exserted; stam. 8; style 3-parted; ach. 3-cornered. - Wet places, ditches, common S. and W. Cal. greenish at base, flesh-colored, brown-dotted like the lvs. Ach. shining. Jl. - Sept. (P. punctatum Ell. P. hydropiperoides Ph.)
8 P. Hydropiper L. Water-pepper. Glabrous; sheaths bristly-ciliate; lvs. lanceolate, tapering to both ends, minutely, pellucid-punctate (very acrid); spikes loose-flowered, slender, short (2 to 5') nodding;. ped exserted; cal. glandular-punctate; stam. mostly 6; sty. 2 or 3-cleft; ach. flattish (rarely obtusely triangular), dull, minutely roughened. - Damp waste grounds, ditches, etc, 1 to 2f high. Lvs. not more than 6" wide. Fls. green and rose-colored. Ach. black. Jl. - Sept. § Eur.
9 P. Careyi Olney. St. erect, hirsute, much branched; lvs. lanceolate, with scattered 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. - Swamps, N. Eng. and N. 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; lvs. 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. - A common species about buildings, fences, wet grounds, etc St smooth, branched, leafy, 1 to 2f high, often colored. Lvs. 2 to 4' long, a fourth as wide, entire, short-stalked, acuminate. Fls. rose-colored, in many spikes, 1 to 2' long, 5 or 6" thick. Jn. - Aug. § Eur.
11 P. Pennsylvanicum L. (Fig. 103, 607.) St. smooth, tumid at the joints; lvs. lanceolate, petiolate; stip. glabrous, not ciliate; spikes oblong, crowded; ped. and often the branches above glandular-hispid; stam. 8; sty. 2-cleft; ach. lenticular with flat sides. - Margins of ponds and ditches, common. St. geniculate, branched above, 2 to 4f high. Lvs. 3 to 5' long, 1/3 as wide, slightly scabrous with appressed hairs. Spikes short and dense, large, and somewhat nodding. Fls. large, rose-colored, pedicellate. Jl.
12 P. incarnatum Ell. St. geniculate smooth below; sheaths smoothish; lvs. lanceolate, smooth except the roughish midvein and margins, or minutely pubescent above; branches and peduncles glandular-dotted; spikes linear, nodding, at length elongated; cal. minutely glandular; stam. 6; sty. 2-cleft; ach. lenticular with concave sides. - In ditches and pools, W, and S. States. Sts. 2 to 3f high.
Lvs. 5 to 9' by 1 to 3'. Fls. flesh-color or white, in spike3 1 to 3' long. Jl. - Sept. (P. lapathifolium, 2d Edit.)
13 P. amphibium L. St. assurgent, prostrate or lecumbent at base, rooting at the lower joints; lvs. oblong-lanceolate and oblong, acute, or rounded or cordate at base, petiolate, smooth, acute or acuminate at apex; spike terminal, ovoid or oblong, dense; sta. 5, sty. 2-cleft. - Marshes, ponds, Can. and U. S., more common North. A very variable species, with largo loaves and a terminal, dense spike of bright red flowers. Stip. large. Lvs. 5 to 7' by 1 to 2', often shining. Spikes 1 to 2' long, the shorter mostly thicker. (Aug. P. coccinum Muhl.)
β. aquaticum. Floating, smooth; lvs. ovate-lanceolate or oblong-ovate, shining, thick; spikes more usually short and thick. (P. fluitans Eaton.)
γ. terrestre. Ascending or erect, more or less hirsute; lvs. lance-oblong, acute or acuminate; sheath hirsute; spikes more commonly elongated. - Varies into the other. (Mr. S. II. Wright.)
14 P. viviparum L. Alpine Bistort. St. low, erect from a creeping rhizome, simple; lvs. linear-lanceolate, revolute at the margin: spike linear, solitary. - White Mts., N. H. to Arc. Am. A dwarf alpine species 6' high, bearing a single spike of white flowers which are often transformed into bulblets while on the stem. Lvs. 1 to 1 1/2' by 2 to 3", with entire, obtuse, smooth stipules. Jl.
15 P. orientale L. Prince's Feather. St. erect, paniculately branched; lvs. largo, with hairy, salver-form stipules; sta. 7; sty. 2. - Native of the East, naturalized in fields and roadsides, throughout the U. S. A tall, showy plant, often cultivated for ornament. Stem 5 - 8f. Lvs. 6 - 8' long;, ovate, acuminate. Spikes numerous, large, red, plume-like, terminal. Aug. † § Eur.
26 P. Virginianum L. St. simple, minutely appressed-hairy above; lvs. ovate and lanceolate, acuminate, short-petiolate; sheath bristly; rac. wand-like, terminal; fls. remote, solitary in each sheath; cal. 4-parted; stam. 5, included; sty. 2, bent downwards, hooked at apex, as long as the shining, tumid-lenticular aehe-nium. - Shades, Can. and U. S. St. 3 to 4f high, the raceme half its length. Lvs. large, 3 to 6' long, half as wide. Fls. greenish-white. Jl., Aug.