Gypsophila muralis L.
Family: Caryophyllaceae
cushion baby's-breath, low baby's-breath
Gypsophila muralis image
Kitty Kohout  
Etymology: Gypsophila: from "gypsum" and "to love"
Plants: drooping, annual, 2"-16" tall, branched, slender forb, smooth above and often fuzzy below
Leaves: linear, less than 1/2" long
Flowers: pink to white, 5-parted, 1/2" - 2/3" wide, stalked, petals finely-toothed, sepals connected; inflorescence a branched cluster (cyme); blooms July-Aug.
Habitat: often in sidewalk cracks
Conservation Status: Introduced - escaped