This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
James' Weed, Mothers' Hearts.
Introduced. Annual and winter annual. Propagates by seeds.
Time of bloom: March to November in the northern part of the country. All the year round where not covered with snow for autumn seedlings bloom in winter if not checked by cold and spring seedlings take up the succession in summer.
Seed-time: April to December.
Range: All cultivated regions of the world.
Habitat: Any soil; invades any crop.
With the exception of Chickweed, this is probably the commonest weed on earth. But usually it is not regarded with so much hostility as are some other plants that really do less harm. It is very prolific and the seeds have long vitality; it absorbs much fertility from the soil; and it often harbors the club-root fungous disease so ruinous to cabbage, cauliflower, turnips, and radishes, and will infect soil where those plants may be cultivated. (Fig. 124.)
The plant is extremely variable, but ordinarily it has a rather deep taproot with many slender rootlets, and the stem is slender and branching, six to twenty inches high. Base leaves usually pinnatifid and tufted in a rosette, though late spring seedlings often send up a fruiting stalk directly from the root, without the tuft of lower leaves; upper leaves lance-shaped and clasping, with small, pointed auricles at base. Flowers white, minute, terminating a lengthening raceme of triangular, flattened, heartshaped silicles, on fine, wire-like pedicels; each "Mother's heart" is partitioned across its narrow thickness and each cell contains about ten reddish brown seeds, a thrifty plant of average size producing about two thousand.
Fig. 124. -Shepherd's Purse (Capsella Bursa-pas-toris). X 1/4.
In cultivated ground the weed succumbs to the constant tillage required, but such plants as spring up after the cultivator has ceased its rounds should be cut or pulled and should not be allowed to seed the ground. Autumn rosettes should be hoe-cut in spring. In meadows and grain fields the weed may be killed while young with a spray of Iron sulfate or Copper sulfate.