20 ELEMENTS OP 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. CKispus), 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 6 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), DOOE-WBED, DoOR-GRASS, WiRE-GRASS. 



Flowers axillary '2 or 3 together, minute and greenish ; stems nearly 

 prostrate ; leaves varying from oblong to lanceolate. 



b. (P. Persioaria), 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.) 



CARYOPHYLLACEJE, 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 



^ In order to make the determination at the time of first floAvering, the class 

 would need also a supply of the fruit of this dock saved the preceding season. 



