Swinecress, greater (Lepidium coronopus =Coronopus squamatus)
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Greater swinecress is a winter or summer annual, and sometimes, biennial broadleaf plant. Found in the Sacramento Valley, San Francisco Bay region, and Sonoran Desert (Imperial Valley) up to 1000 feet (300 m), it is particularly problematic in Imperial Valley vegetable crops. The California Department of Food and Agriculture lists greater swinecress as a “B” noxious weed.
Greater swinecress is found in vegetable crops, alfalfa pastures, orchards, fields, gardens, turf, roadsides, ditch banks, and other disturbed sites.
Cotyledons (seed leaves) are more or less linear with slightly rounded tips, hairless, and about 1/5 to 3/5 inch (5–15 mm) long. The first true leaves resemble the cotyledons but are longer, about 1/3 to 4/5 inch (8–20 mm) long.
The young plant exists as a rosette until maturity when the flower stem develops.
The mature plant grows flat (prostrate) or low over the ground, usually with many branching stems. Leaves look feathery. They are about 12 inches (30 cm) long, deeply divided into lobes that that are toothed or lobed again, hairless to short haired, and alternate along the stem. Upper leaves are practically stalkless; lower leaves are stalked. Unlike lesser swinecress, which has a skunklike odor, greater swinecress does not have a strong scent.
Flowers bloom from May through October. Flowers are single on stalks and each flower has four small, white, egg-shaped flower petals that are about 1/16 inch (1.5 mm) long.
Fruit consist of generally egg-shaped, wrinkly pods, about 1/16 inch (1.5 mm) long and 1/10 inch (2.5 mm) wide. Each pod is two-chambered and each chamber contains 1 seed.
One kidney-shaped, yellow-brown seed is contained within each pod chamber.
Fruits consist of generally egg-shaped, wrinkly pods, about 1/16 inch (1.5 mm) long and 1/10 inch (2.5 mm) wide. Each pod is two-chambered; each chamber contains 1 seed.
Greater swinecress reproduces by seed.
Related or similar plants
- Lesser swinecress, Lepidium didymum
- Mayweed chamomile, Anthemis cotula
- Wild celery (young), Cyclospermum leptophyllum