POPULAR FLORA. 193 



Calyx of 5 (rarely 4) nearly similar sepals, all more or less petal-like. 



Stamens 4 to D: aliene generally small; cotyledons narrow, {Polygonum) Knotweed. 



Stamens 8: styles 3: akene triangular, shaped like a beechnut, much longer than tlie 

 calyx: cotyledons very broad and folded in the mealy albumen: root annual: 

 leaves nearly halberd-shaped : flowers white, corymbed, {FaffOj]i)rum) *Buck\vheat. 



Calyx of G sepals, and 



All alike and petal-like (white): stamens 9: styles 3, {Rheum) *EiiUEAr.B. 



Three outer ones herbaceous and spreading: three inner larger, especially after flow- 

 ering, "wheu they close over the triangular aUene; flowers dicecious: leaves 

 sour, eared or halberd-shaped, {Rumex, ^ Acetosella) Soeeel. 



Flowers perfect or polygamous; leaves bitter; coarse herbs, {liumex) Bock. 



Knotweed. Polygomim. 



* Flowers single or several together in the axils of the leaves, greenish or whitish: sheaths (stipules) 



cut-fringed or torn into narrow shreds. 



1. Common Knotweed, Knotgrass, or Goosegrass. Spreading on the ground, small ; leaves 



sessile, lance-shaped or oblong, pale; a variety has nearly upriglit stems and oblong or oval leaves. 

 The commonest weed in yards and waste places. P. aviculdre. 



2. Slender K. Upright, somewhat branched; leaves linear, acute, sheaths fringed. Dry soil. P.Unue. 



* * Flowers in terminal heads, spikes, or racemes. 



•*- Not twining nor climbing, and leaves not heart-shaped nor arrow-shaped: calyx petal-like and 



5-parted, except in No. 10. 

 8. Okiextal, K. or Prince's Feathee. Tall annual, 4° to 7° high; leaves ovate; spikes of rose- 

 cffllored flowers long and nodding; stamens 7; akene flatfish. Gardens. P.orientale. 



4. Water K. Stems floating in water, or rooting in mud, or upright; leaves lance-shaped or oblong j 



spike thick and short; flowers rose-red; stamens 5; styles 2. P. amphibium. 



5. Fennstltania K. Stem upright, 1° to 3° high; leaves lance-shaped; spike oblong, thick, erect, 



its peduncle beset with club-shaped bristles or glands; flowers rose-colored; stamens 8; akene 

 flat. Moist ground. P. Pennsylvdnicum. 



6. Lady's-Thujih K. Stems, &c. like the last and next, but no bristles on the peduncle; leaves with 



a darker spot on the upper side; spike short and thick, erect; flowers greenish-purple; stamens 

 6. Very common in waste places. P. Persicdria. 



7. Smaetweed or Watee-Pepper K. Upright, annual, 1° or 2° high, very acrid and biting to the 



taste; leaves and also the greenish sepals marked with fine transparent dots; spikes short but 

 loose, drooping; akene flattish or bluntly triangular. Moist ground, common in waste places, 

 yards, and near dwellings. P. Hydropiper. 



8. Wild Smaetweed K. Upright, 1° to 8° high from a perennial root, biting like the last, and the 



leaves dotted; spikes very slend^ erect, whitish or flesh-color; stamens 8; styles 3; akene sharply 

 triangular. Wet places. P. acre. 



9. Mild Watee-Peppee K. Upright, 1° to 3° high; often creeping at the base and rooting in water; 



leave? roughish, not biting, narrowly lance-shaped; spikes slender, erect, rose-color; stamens 8; 

 style 3-cleft at the top ; akene sharply triangul.ir. Shallow water. P.hydrojnperoides. 



10. ViEGiNIA K. Stem 2° to 4° high, angled; leaves large, ovate or lance-ovate, taper-pointed; flow- 



