POLYGONACEAE (BUCKWHEAT FAMILY) 103 
Introduced. Annual. Propagates by seeds. 
Time of bloom: June to October. 
Seed-time: July to November. 
Range: Throughout the American Continent except the extreme 
North, and in most parts of the world. 
Habitat: Soil either dry or moist. Invades nearly all crops. 
The seeds of this weed form one of the most common impurities 
of commercial seeds, particularly of red clover. In a bulletin 
issued by the Agricultural Experiment 
Station of Nevada, concerning “Clover 
Seeds and their Impurities,” it is 
stated that of red clover samples sub- 
mitted for inspection (obtained in all 
parts of the country), 62.9 per cent con- 
tained seeds of Persicaria. (Fig. 61.) 
Stems six inches to two feet tall, 
often red or purplish at base, nearly 
smooth, erect or sometimes spreading. 
Leaves lance-shaped, smooth or with 
fine hair roughening the edges, pointed 
at both ends and generally blotched 
near the center with a large brownish 
spot. It is related that Joseph once 
hurt his hand while working in his car- 
penter’s shop. Mary wished to make 
a healing poultice with this plant, but 
‘*She could not find it at her need 
And so she pinched it for a weed,” 
since when its leaves have always 
borne the mark of the Lady’s thumb; 
the sheathing stipules at their base are 
fringed with short bristles. Flower- 
Fie. 61.—Lady’s Thumb - 
(Polygonum Persicaria). X }. 
spikes numerous, dense, erect, a half-inch to two inches long; 
calyx pink or purplish with four or five obtuse lobes, usually 
six stamens, and a two- or three-parted style. Achenes lens- 
shaped or sometimes three-angled, smooth, shining, jet-black. 
In some localities the plant is said to harbor the corn-root 
aphis, the louse appearing with the first leaves. 
