- Name also: Corn Spurry (USA)
- Family: Pink Family – Caryophyllaceae
- Growing form: Annual herb.
- Height: 10–40 cm (4–16 in.). Often with many stems. Stem ascending–erect, glabrous–with glandular hairs, often sticky. Internode below inflorescence shorter than lower ones.
- Flower: Corolla regular (actinomorphic), white, approx. 1 cm (0.4 in.) broad; petals five, 3.5–5 mm (0.14–0.2 in.) long, slightly longer than sepals. Sepals 5, with glandular hairs, membranous margins. Stamens usually 10 (sometimes 5). Gynoecium syncarpous, with 5 styles. Inflorescence a many-branched cyme.
- Leaves: Opposite, but apparently whorled, stalkless, stipulate, erect–spreading. Blade thread-like–linear, with entire margins, semi-cylindrical, underside grooved, quite fleshy, with glandular hairs, lime–dark green. Lowest leaves around same length as internodes. Stipules membranous, thin, dropping early.
- Fruit: Egg-shaped, usually green, 5-valved, 4–7 mm (0.16–0.28 in.) long capsule. Seed dark, with membranous margins. Membranous margin very slight and glossy.
- Habitat: Arable land, gardens, yards, railway areas, roadsides, wasteland, rocks, gravel pits, sandy areas, shores.
- Flowering time: June–September.
Corn spurrey probably arrived in Finland with early agriculture, perhaps from somewhere in the northern Alps. It still follows people, growing mainly on cultivated land and acidic peaty and sandy fields. Although corn spurrey is a delicate annual, thick stands have a detrimental effect on cereal growth. The species is difficult to eradicate because it has a store of seeds in the ground, in the best – or worst – case with up to 10,000 seeds per square metre.
Corn spurrey is such an obvious weed in Finland that it is hard to believe it was cultivated in ancient times. It was grown as late as the beginning of the last century in northern Germany and Denmark as cattle fodder, and it is said to have had a positive effect on milk production. Still earlier it has also been an important human food, and its highly nutritious oil-rich seeds were used to make porridge in the Stone Age. The seeds are however so small that the trouble of collecting them probably put paid to their culinary use as soon as easier food became available.
Like many other weeds, corn spurrey has a changeable appearance. Especially the properties of the seeds, as well as the size and amount of branching of the stem, change from plant to plant. Corn spurrey is usually grouped into a number of subspecies, of which sticky-haired ssp. sativa has spread to some extent across all of Finland. The southern subspecies ssp. arvensis has spread mainly into western Finland. Ssp. maxima specialised in growing as a weed in flax fields, but it now seems to have disappeared. Pearlwort spurrey (S. morisonii) is a native species which grows on rocky outcrops and sandy banks. It resembles corn spurrey in many ways, but it is glabrous while corn spurrey is often sticky with glandular hairs. Pearlwort spurrey also has shorter leaves than corn spurrey and its leaf whorls become further apart towards the crown.