254 FLOWERS OF FIELD, HILL, AND SWAMP 



65. Red-veined Dock 



R. sanguineus is similar, with red veins in the leaves. Leaves 

 somewhat fiddle-shaped, the lower with long petioles. 



66. Smaller Green Dock 



R. conglomeratus has a leafy panicle of pedicelled, small 

 flowers. Leaves petioled, oblong to lance-shaped, acute, i to 

 5 inches long. 



67. Field or Sheep Sorrel 



R. Acetosella bears a small panicle of reddish fiowers, and 

 smooth, halberd-shaped leaves, mostly clustered at the root. 

 Low, sour herbs, so common as to redden the fields where 

 they grow. The upper leaves clasp the stem with thin, mem- 

 branous, stipular sheaths. Common everywhere in dry soil. 



68. Knotweed. Doorweed 



Polygonum aviculare. — Family, Buckwheat. Color, pink. 

 Leaves, small, sessile, blue-green, less than i inch long, narrow. 

 Sheaths silvery, membranous. Time, summer. 



Corolla, none. Calyx, green, bordered with pink. Flowers, 

 very small, in axillary clusters. 



There is a puzzling variety among the species of this genus, 

 some of which are common weeds ; others, rarer, aspire to pretti- 

 ness. Many of them frequent wet places, and are found along 

 roadsides. This one is smooth, much jointed, prostrate, slender. 

 Very common. 



6g. Erect Knotweed 



F. erectum is stouter, erect, 2 feet or less tall, with broader 

 leaves. There is a yellowish tint to the flowers and stein by 

 which it may be known. Flowers i or 2 in the axils. Leaves 

 jointed to the sheaths. 



70. Pennsylvania Persicaria 



P. Pennsyh'dniatm has lance-shaped leaves hairy along the 

 mid-rib. The dark, pink flowers are in short, thick, obtuse 



