- Latin synonym: Gypsophila muralis
- Name also: Low Baby’s-breath (USA)
- Family: Pink Family – Caryophyllaceae
- Growing form: Annual herb.
- Height: 5–15 cm (2–6 in.). Stem abundantly branched from base, glabrous–virtually glabrous, bluish green.
- Flower: Corolla regular (actinomorphic), delicate pink, approx. 0.5–1 cm (0.2–0.4 in.) wide; petals 5, entire, dark-veined. Corona (an additional small corolla) not present. Calyx campanulate, 5-lobed, white-striped, lacking epicalyx. Stamens 10. Styles 2. Inflorescence a lax, many-flowered cyme.
- Leaves: Opposite, stalkless. Blade linear, with entire margin, bluish green.
- Fruit: Narrowly egg-shaped, splitting into 4 lobes, capsule longer than calyx.
- Habitat: Meadows, wasteland, banks, paths, roadsides, railway embankments, sports fields and playgrounds. Also an ornamental.
- Flowering time: July–September.
- Endangerment: Vulnerable.
Annual gypsophila arrived in Finland in ancient times, and the northern limit of its habitat runs through central Finland. Casual finds have been recorded however in the harbour towns along the Gulf of Finland as far north as Oulu. It can be difficult to differentiate between an annual plant’s established and casual stands, but the species seems to have been declining rapidly for a long time, and even feral plants have become increasingly difficult to find. The decline of the species probably began at the beginning of the 20th century with the decreasing importance of cattle farming, the paving over of yards, and the rise of cultivated lawns and buildings. Annual gypsophila typically grows in culturally influenced places, and as such it can be found on dry meadows, field margins, railway embankments, gravelly yards and pushing up between marketplace cobblestones. It is a weak competitor which demands an open, even plantless environment, but on the other hand it can withstand being tramped on by heavy traffic. There is also a refined form of annual gypsophila which is cultivated as an ornamental and which is taller with redder flowers. It sometimes spreads from hanging baskets to city yards, grassy roadsides, paths and around sand-fields.
Annual gypsophila is to a certain extent reminiscent of red sand-spurrey (Spergularia rubra), which thrives in the same cultural habitats and has pale purple flowers, a limp stem, and membranous stipules at the base of its leaves. Another feral representative of its genus, fastigiate gypsophila (G. fastigiata), does not really resemble its relative apart from the fact that they are both cultivated ornamentals.