- Name also: Chickenwort, Craches, Maruns, Winterweed, Common Chickweed
- Family: Pink Family – Caryophyllaceae
- Growing form: Annual herb.
- Height: 5–30 cm (2–12 in.). Stem limp–ascending, thin, hairy on one side. Forming mat-like stands.
- Flower: Corolla regular (actinomorphic), white, 8–10 mm (0.32–0.4 in.) broad; petals 5, deeply 2-lobed (looks like 10 petals), 2–3 mm (0.08–0.12 in.) long, slightly shorter than calyx or sometimes the same length, or completely lacking. Sepals 5, hairy, with membranous margins. Stamens usually 3–7. Gynoecium syncarpous, with 3 styles. Inflorescence a sparsely–abundantly flowered, 2-branched cyme; subtending bracts green.
- Leaves: Opposite, usually stalked, uppermost stalkless. Blade ovate, taper-tipped, with entire margins, glabrous, light green.
- Fruit: Egg-shaped, 6-valved, 4–6.5 mm (0.16–0.26 in.) long capsule.
- Habitat: Gardens, yards, around inhabited areas, fields, roadsides, banks, paths, wasteland, seashores, seaweed banks, archipelago bird rocks.
- Flowering time: May–October.
Common chickweed likes habits that are wet or damp at least some of the time, such as beside ditches, shores, and under eaves in buildings. The species perseveres in quite dry places and doesn’t need much light: it is often the only plant to spread under buildings, into dim staircases, onto the earthen floors of outside buildings, hollows in tree roots and similar places. Its choice of habitat is thus very wide.
Chickweed can germinate and flower at almost any time of the year at all. The buds don’t suffer much from a little frost, and in a temperate coastal climate flowering continues as soon as a mild spell begins. As it mainly self-pollinates, pollination is not dependent on insects being active. The flowers are visited by flies, however, so cross-pollination can occur. The seeds spread easily and water chickweed has spread practically everywhere that there are people: only the Arctic tundra and high mountains are without it.
Chickweed is adaptable and is thought to be the world’s most common flowering plant; it has often also been thought of less flatteringly as an annoying weed. This annual, fragile plant doesn’t do much harm in the field, but in gardens and vegetable gardens it is easy to remove cultivated plant shoots by accident while weeding. Chickweed can make a juicy addition to salad or be dried and milled into green flour. It also has a good reputation as a diverse medicinal plant.
Chickweed looks quite similar to the larger plants wood stitchwort (S. nemorum) and water chickweed (Myosoton aquaticum). It can be differentiated from three-veined sandwort (Moehringia trinervia) by the latter’s three-veined leaves. One quite reliable and easy identification marker is common chickweed’s one-sided hairiness, which stands out very well when light shines from behind it.