288 BUCKWHEAT FAMILY. 



P. t6nue. Rocky dry soil : slender, upright, with thread-like branches, 

 along which the upper flowers form a loose leafy spike ; leaves narrow linear, 

 acute ; akene shining. 



2. Flowers collected in terminal spikes or spike-like racemes, rose-purple or flesh- 

 color, or rarely white or greenish, 



* Leaves small and thread-like or at length none : (he sheaths truncate, naked, rigid: 



many-jointed raceme with a single flower under each bract. 



P. articulatum. Sandy shores and barrens : a slender little plant, bushy- 

 branching, 4' -12' high; flowers rose-colored, nodding; stamens 8; akene 

 triangular. 



* * Leaves ovate, short-petioled : sheaths cylindrical, fringed-hairy : greenish 



flowers 1-3 from each bract of the long and slender spikes, unequally 4- 

 parted ; the 2 styles re flexed on the lenticular akene and hooked at the tip. 

 P. Virginianum. Thickets : 2 -4 high, nearly smooth ; leaves rough- 

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



* * * Leaves lanceolate, oblong, or ovate, chiefly petioled : sheaths cylindrical: 



flowers several from each bract of the spike, ^-parted. 



H- Sheaths mostly with an abruptly spreading foliaceous border (which sometimes 

 falls off") : tall, 3 - 8 high, with dense cylindrical nodding spikes of rose- 

 colored flowers, and flat akenes. 



P. orientale, PRINCES' FEATHER. Gardens and cultivated grounds, from 

 India : with large ovate pointed leaves, and 7 stamens. 



P. Careyi. Swamps from Pennsylvania N. & E. : with lanceolate leaves, 

 glandular bristly peduncles, and 5 stamens. 



+- H- Sheaths truncate, without a border. < 



w- Herbage and flowers not acrid nor punctate with pellucid glands or dots. 

 = In moist soil : leaves lanceolate : plants nearly smooth. (T) 



P. incarnktum. Tall, 3 -6 high ; leaves tapering from near the base 

 to a narrow point (4 ; - 12' long) ; sheaths smooth and naked ; peduncles rough 

 with scattered sessile glands ; spikes linear, nodding ; flowers flesh-color or pale 

 rose ; the 6 stamens and 2 styles included ; akene flat with concave sides. 



P. Pennsylvanicum. Stems l-3 high, the branches above and pe- 

 duncles bristly with stalked glands ; sheaths naked ; spikes oblong, thick and 

 blunt, erect ; flowers rose-purple ; stamens 8, a little protruding ; style 2-cleft ; 

 akene with flat sides. 



P. Persicaria, 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. 



= = In water : stems rooting below. ^ 



P. amphibium. WATER P. Chiefly N. : stems often simple bearing a 

 single ovate or oblong dense spike or head of pretty large and showy rose-red 

 flowers ; leaves oblong, heart-oblong, lance-ovate or lanceolate, mostly long- 

 petioled, often floating ; sheaths not fringed ; stamens 5 ; style 2-cleft. 



P. hydropiperoides. Commonest S. : 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. 



t-v -w- Herbage (smooth) punfjentiy acrid: leaves and pale sepals marked with 

 pellucid dots or glands, in which the acrid quality resides : sheaths fringed 

 with bristles. 



P. acre, WATER SMARTWEED. Shallow water or wet soil : stems rooting 

 at the decumbent 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. 2/ 



