Stellaria media is an annual or winter annual herb from a slender taproot, stems weak, branching, light green with a single line of hairs down stem and petiole, to 40 cm, (solitary plants can spread to as much as 1.5 m) usually prostrate, mat-forming.
Leaves opposite, to 2.5 cm long, egg-shaped, sessile near ends of stems, stalked closer to base, usually bright, light green.
Flowers white, solitary or in small clusters, 0.5 cm wide, petals deeply split, shorter than sepals, anthers red-violet; sepals hairy; flowers single or in loose clusters at ends of stems; blooms spring and fall mostly April-May (Hough 1983) last one day, self-fertile (autogamous) (Mulligan and Kevan 1973).
Fruit dry capsule longer than sepals, opening by six teeth, seeds 8-10, ca 0.1 cm; seeds eaten by birds, plants eaten by rabbits (Martin et al. 1951).
Wetland status: UPL.
Frequency in NYC: Occasional.
Habitat: An agricultural weed, more common on open ground, lawns, gardens, less common in natural areas. Intolerant of drought, prefers light partial shade, high nitrogen and moist soil, pH 5.2-8.2.
Notes: Able to flower and set seed in the cooler parts of the year (down to 2°C). Winter plants store sugar rather than starch, to prevent freezing of cells. Temperatures higher than 30° C inhibit seed germination. Seeds may be viable for over 60 years in soil. Plants flower after about 5 weeks and live up to about 7 weeks (Turkington et al. 1980). Outcompetes other plants by shading or smothering seedlings. Accumulates nitrates, tolerant of cold (range extends into the Arctic). Chickweed can transmit a number of viruses to crop plants through pollen and aphids without showing symptoms. Cucumber mosaic virus causes mottled leaves in chickweed. The nematode genus Trichodorus is a vector for the tobacco rattle virus, that infects potatoes, but preferentially attacks chickweed in potato fields (Turkington et al. 1980).