POPULAR FLORA. 
193 
Calyx of 5 (rarely 4) nearly similar sepals, all more or less petal-like. 
Stamens 4 to 9: akene generally small : cotyledons narrow, ( Polygonum ; Knotweeix 
Stamens 8 : styles 3 : akene triangular, shaped like a beechnut, much longer than the 
calyx: cotyledons very broad and folded in the mealy albumen: root annual: 
leaves nearly halberd-shaped : flowers white, corymbed, ( Fagopijrum ) ^Buckwheat. 
Calyx of 6 sepals, and 
All alike and petal-like t white): stamens 9: styles 3, {Rheum) * Rhubarb. 
Three outer ones herbaceous and spreading : three inner larger, especially after flow- 
ering, when they close over the triangular akene : flowers dioecious : leaves 
sour, eared or halberd-shaped, ( Rumex , § Acetosella) Sorrel. 
Flowers perfect or polygamous : leaves bitter: coarse herbs, {Rumex) Dock. 
Knot weed. Polygonum. 
* 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 upright stems and oblong or oval leaves. 
The commonest weed in yards and waste places. P. aviculare. 
2. Slender K. Upright, somewhat branched; leaves linear, acute, sheaths fringed. Dry soil. P.tenue. 
* * 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. 
3. Oriental K. or Prince’s Feather. Tall annual, 4° to 7° high; leaves ovate; spikes of rose- 
colored flowers long and nodding ; stamens 7 ; akene flattish. Gardens. P. orientate. 
4. Water K. Stems floating in water, or rooting in mud, or upright; leaves lance-shaped or oblong; 
spike thick and short; flowers rose-red; stamens 5; styles 2. P. amphibium. 
5. Pennsylvania 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. Pennsylvanicum. 
6. Lady’s-Thumb 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. Persicaria. 
7. Smartweed or Water-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 Smartweed K. Upright, 1° to 3° high from a perennial root, biting like the last, and the 
leaves dotted; spikes very slender, erect, whitish or flesh-color; stamens 8; styles 3; akene sharply 
triangular. Wet places. p. acre. 
9. Mild Water-Pepper K. Upright, 1° to 3° high; often creeping at the base and rooting in water; 
leaves roughish, not biting, narrowly lance-shaped; spikes slender, erect, rose-color; stamens 8; 
style 3-cleft at the top; akene sharply triangular. Shallow water. P. hydropiperoides. 
10. Virginia K. Stem 2° to 4° high, angled; leaves large, ovate or lance-ovate, taper-pointed; flow- 
