Buckwheat Family (Polygonaceæ)
This family is divided into seven genera and many of these are further divided. They are all inconspicuous in flower. The genus Rumex, to which our common Sorrels belong, contain seventeen species: that of Polygonum, which contains the Knot-weeds, has 32 species included in its six sub-genera.
(A) Lady’s Thumb; Persicaria; Knotgrass (Polygonum persicaria) (European). This is a very common weed everywhere in damp places, especially about farmhouses. The small, crimson-pink flowers are in dense spikes terminating the branching stems that are from 1 to 3 feet high. The lanceolate pointed leaves, that alternate along the angled and sheathed stem, are rather rough and usually have a dark triangular spot in the middle.
(B) Common Smartweed; Water Pepper (P. hydropiper) has similar shaped flowers of a greenish color. The leaves are lanceolate and very acrid. It is very abundant in wet places throughout our range.