20 ELEMENTS OF BOTANY. 
generally with a little knob or tubercle on its outer surface. 
Stamens 6. Styles 3, short, stigmas much fringed to aid in 
wind-fertilization. Coarse herbs, some of them noxious 
weeds. 
(R. crispus), YELLow Dock. 3-4 ft. high, smooth, with large 
lanceolate or oblong leaves, strongly wavy-margined. Inner sepals 
round-heart-shaped, most of them tubercle-bearing.? 
II. POLYGONUM, KNOTWEED. 
Calyx generally of 5 colored or greenish sepals. Stamens 
4-9. Styles short and thread-like, usually 3. Akene lens- 
shaped or triangular. Plants with stems enlarged at the 
joints, the latter covered with thin sheathing stipules. 
Flowers small, greenish, white, or reddish. 
a. (P. AVICULARE), DoorR-WEED, Door-GRAss, WIRE-GRASS. 
Flowers axillary 2 or 3 together, minute and greenish; stems nearly 
prostrate; leaves varying from oblong to lanceolate. 
b. (P. Persicaria), LADY’s THuMB, HEART-WEED, HEART’S-EASE. 
Flowers in dense ovoid or oblong spikes, with small, thin, dry bracts ; 
calyx greenish-purple; stamens mostly 6; stems about 1 ft. high; 
leaves with a dark triangular or heart-shaped spot near the middle. 
c. (P. SAGITTATUM), SCRATCH-GRASS, TEAR-THUMB. Flowers 
whitish, in small heads; stamens generally 8; stems 3-5 ft. long, 
climbing by the sharp, recurved prickles on the angles of the stem 
and midribs of the leaves; leaves short-petioled, arrow-shaped. 
Division II. 
POLYPETALOUS PLANTS. FLOWERS WITH SEPARATE PETALS. 
(IN A FEW THE PETALS ARE WANTING.) 
CARYOPHYLLACEA, PINK FAMILY. 
Herbs with simple, entire, opposite leaves, symmetrical 
flowers on the plan of 4 or 5; stamens distinct, twice as 
many as the sepals, or fewer; styles usually 2-5; ovules 
1Jn order to make the determination at the time of first flowering, the class 
would need also a supply of the fruit of this dock saved the preceding season. 
