Stellaria media

Stellaria media, chickweed, is an annual flowering plant in the family Caryophyllaceae. It is native to Eurasia and naturalized throughout the world, where it is a weed of waste ground, farmland and gardens. It is sometimes grown as a salad crop or for poultry consumption.

Chickweed is a hardy annual which flowers throughout the year in northern Europe, in mild weather. The stems are terete and glabrous with a lax and sprawling growth habit, up to 40 cm (16 inches) long and 1 millimetre (1⁄16 in) in diameter, with a line (very occasionally 2 lines) of hairs running straight down its length, alternating sides at the nodes. The petioles are 5 to 8 mm long with hairy margins. The leaves are green, hairless, oval and opposite, 6 to 25 mm (1⁄4 to 1 in) long by 3 to 10 mm (1⁄8 to 3⁄8 in) wide with a hydathode at the tip.

The flowers are small, less than 1 cm in diameter, with 5 bifid white petals, 1–3 mm long, nestled inside the larger (3–5 mm long) sepals. These sepals have long, wavy (villous) hairs on their outer (distal) sides and are oval in shape, and usually 5 in number. There are often only 3 stamens but sometimes more (up to 8) and 3 styles. Many publications state that chickweed sometimes has no petals at all, but this may be due to confusion with lesser chickweed, which used to be considered a subspecies but is now considered to be a species in its own right.

The flowers quickly form capsules. Plants may have flowers and capsules at the same time.

The anthraquinones emodin, parietin (physcion) and questin, the flavonoid kaempferol-3,7-O-α-L-dirhamnoside, the phytosterols β-sitosterol and daucosterol, and the fatty alcohol 1-hexacosanol can be found in S. media. Other flavonoid constituents are apigenin 6-C-beta-D-galactopyranosyl-8-C-alpha-L-arabinopyranoside, apigenin 6-C-alpha-L-arabinopyranosyl-8-C-beta-D-galactopyranoside, apigenin 6-C-beta-D-galactopyranosyl-8-C-beta-L-arabinopyranoside, apigenin 6-C-beta-D-glucopyranosyl-8-C-beta-D-galactopyranoside, apigenin 6, 8-di-C-alpha-L-arabinopyranoside. The plant also contains triterpenoid saponins of the hydroxylated oleanolic acid type. Proanthocyanidins are present in the testa of seeds.

Chickweeds are recognisable by the line of hairs down the stem. The species most likely to be confused with chickweeds are mouse-ears (Cerastium), however, mouse-ears are hairy all over (leaves and stems).

Common chickweed can be differentiated from lesser chickweed by the presence of white petals on the former and from greater chickweed by 3–8 stamens present compared to 8–10 found in greater chickweed. Water chickweed has petals longer than the sepals.

The name Stellaria media was published by Domínique Villars in Histoire des plantes du Dauphiné in 1789. It has accumulated a huge number of synonyms since then, as well as many putative varieties and subspecies, very few of which are accepted today.