BUCKWHEAT FAMILY. 371 



- - Sheaths with an abruptly spreading leafy border (which sometimes 



falls off*), or else the sheaths and bracts bristly-ciliate. 



*+ Style 2-cleft, and akene somewhat flattened ; sepals not punctate. 



= y. Stem rooting at base, ascending. 



P. Hartwrightii, Gray. Stem very leafy, the leaves narrow and 

 short-stalked ; stems rough-hairy, at least on the sheaths and bracts ; 

 sheaths generally with a conspicuous, leafy border ; flowers and fruit 

 like P. amphibium. Wet or muddy places, N. Eng., W. 

 = = (D Stems erect. 



P. Careyi, Olney. Swamps from Penn. , N. and E. ; leaves narrowly 

 lanceolate, roughish, tapering both ways ; sheaths margined or ciliate ; 

 peduncles glandular, bristly ; stamens 5. 



P. orientdle, Linn. PRINCE'S FEATHER. Gardens and cultivated grounds, 

 from India ; with large, ovate, pointed leaves, and 7 stamens ; very tall, 

 with ciliate or bordered sheaths, soft-hairy ; flowers in cylindrical nod- 

 ding spikes. 



P. Persicaria, Linn. LADY'S THUMB. Nat. from Eu., near dwellings ; 

 about 1 high ; upper face of leaves with a dark blotch near the middle ; 

 sheaths somewhat bristly-ciliate ; spikes oblong, dense, erect, on naked 

 peduncles; flowers greenish-purple; stamens mostly 6; style 2-3-cleft ; 

 akene either flattish or triangular. 

 +* *-* Style generally 3-parted and the akene triangular ; sepals mostly 



dotted. 

 = Herbage not acrid nor punctate with pellucid dots. 



P. hydropiperoldes, Michx. Stems slender, rising out of shallow 

 water, l-3 high ; leaves narrowly lanceolate or lance-oblong ; sheaths 

 hairy and fringed with long bristles ; spikes erect, slender ; flowers 

 small, pale or white ; stamens 8 ; style 3-cleft ; akene sharply triangular. 

 Common. 11 



= = Herbage (smooth*) pungently acrid ; leaves and pale sepals marked 

 with pellucid dots or glands, in which the acrid quality resides. 



P. acre, HBK. WATER SMARTWEED. Stems rooting at the decum- 

 bent base, rising 2-4 high ; leaves lanceolate or linear, taper- pointed ; 

 spikes slender, erect ; flowers whitish or pale flesh-color ; stamens 8 ; 

 akene sharply triangular, shining. Common in wet places. 2/ 



P. Hydrdpiper, Linn. COMMON S. or WATER PEPPER. Low or wet 

 grounds N. ; l-2 high; leaves oblong-lanceolate; spikes nodding, 

 mostly short ; flowers greenish-white ; stamens 6 ; akene either flat or 

 obtusely triangular. 



* * Leaves ovate, short-petioled ; sheaths cylindrical, f ringed-hairy ; green- 

 ish flowers 1-3 from each bract of the long and slender spikes, unequally 

 ^-parted ; the 2 styles reflexed on the lenticular akene and hooked at the tip. 

 P. Virginianum, Linn. Nearly smooth, 2-4 high; leaves rough- 



ciliate, 3'-6' long ; flower somewhat curved ; stamens 5. Frequent in 

 thickets. 2/ 



* * * Leaves heart-shaped or arrow-shaped, petioled; sheaths half- 



cylindrical. 



4- TEAR THUMB. Stems with spreading branches, the angles and petioles 

 armed with sharp reflexed prickles, by which the plant is enabled almost 

 to climb ; flowers in peduncled heads or short racemes, white or flesh- 

 color. (I) 



P. arifdlium. Linn. Low grounds ; leaves halberd-shaped, long-peti- 

 oled ; the peduncles glandular-bristly ; stamens 6 ; styles 2 ; akene len- 

 ticular. 



