Coronopus didymus (L.) Sm. - Wart Cress

Coronopus didymus plant

Family - Brassicaceae

Stems - Repent, decumbent, or ascending, multiple from the base, radiating from a central point, from a long taproot, to 30cm long, herbaceous, terete, glabrous, green.

Leaves - Alternate, petiolate, pinnate, to 4-5cm long, 2cm broad, glabrous. Divisions of the leaves opposite, lobed or divided again, acute, linear-elliptic to linear oblong. Apices of ultimate divisions with a somewhat hardened point.

Coronopus didymus leaves

Inflorescence - Small raceme to 4cm long, opposite one of the stem leaves, compact in flower, quickly elongating in fruit. Axis glabrous. Pedicels to 2mm long in fruit.

Coronopus didymus inflorescenceInflorescence.

Flowers - Greenish, minute. Petals absent. Sepals 4, to 1mm long, .75mm broad, strongly cupped, glabrous, with scarious margins, acute to rounded at the apex. Stamens 2, to .75mm long. Filaments white, swollen at the base, glabrous, succulent. Anthers purple, .1mm long. Staminodia 4, shorter than the stamens, one staminode arising on each side of the fertile stamens, with minute green nectaries at the base between the fertile stamen and the staminode. Ovary superior, green, glabrous, 1mm broad, .8mm long, compressed. Style absent. Stigma sessile between the two halves of the ovary. Fruits glabrous, 3-4mm broad, 2mm long, slightly compressed, sub-biglobose, 2-seeded.

Coronopus didymus flowersFlowers.

Coronopus didymus fruitsFruits.

Flowering - April - October.

Habitat - Waste ground, open places, lawns.

Origin - Native to Europe.

Other info. - This sprawling weed can be found in just a handful of southeast Missouri counties but is spreading. The plant is easy to ID in the field because of its spreading stems, pinnate leaves, and biglobose fruits. The species epithet "didymus" means "the testes" referring to the fruits.

Photographs taken in Salter Path, NC., 3-2-03.


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