Shepherd's-purse is a winter annual broadleaf weed, but may grow all year in cool coastal areas of California. It is common throughout California to about 7600 feet (2300 m). It inhabits agricultural land and other disturbed areas. Its fruit has a peppery flavor and is sometimes added as a spice to salad greens. However, shepherd’s-purse seeds and leaves contain compounds called glucosinolates, which cause digestive irritation when consumed in quantity.
Habitat
Agronomic and vegetable crop fields, orchards, vineyards, nurseries, gardens, turf, landscaped areas, roadsides, and other disturbed places.
Seedling
Cotyledons (seed leaves) are narrowly football shaped with a rounded tip, pale green, about 1/12 to 1/5 of an inch (2–5 mm) long, with tiny granules on the surface. The first and next few leaves are narrowly football shaped to egg shaped, with rounded tips, and smooth to toothed edges. Later leaves are typically toothed to deeply lobed. True leaves are covered with star-shaped hairs that distinguish shepherd's-purse from most other weed seedlings.
Young Plant
Until the flower stem develops at maturity, plants exist as flat basal rosettes.
Mature Plant
Plants grow to about 20 inches (50 cm) tall. Leaves vary in shape and are lightly covered with both simple and forked hairs. Rosette leaves are about 1-1/5 to 4 inches (3–10 cm) long and their edges range from nearly smooth to deeply lobed. Flower stems are single or branched. Stem leaves are sparse, reduced in size, and stalkless. Leaves have toothed or lobed edges, lobed bases clasping the stem, and are alternate to one another.
Flowers
Flowering takes place mostly in late winter or spring, but can take place year-round under favorable conditions. Flower stalks grow erect or slightly horizontal and are mostly 2/5 to 3/5 of an inch (10–15 mm) long. The four white flower petals are sometimes tinged pale pink, and narrow toward the base (clawed).
Fruits
Fruits consist of flat, heart or triangular-shaped pods making this species easy to recognize when mature and distinguishes it from other plants in the mustard family. Each pod has two chambers divided by a narrow ridge (septum). The pods attach to the stem on long stalks. They are peppery in taste, and eventually open to release many seeds from each chamber.
Seeds
Seeds are oblong, slightly flattened, a dull, reddish to yellowish brown, and tiny—about 1/25 of an inch (1 mm) long.
Reproduction
Reproduces by seed.
