baby's-breath
Also known as "bebe's breath", "maiden’s breath" and "gyp" after the genus name.
Gypsophila, commonly known as baby's breath, is a genus of popular flowering plants in the carnation family (Caryophyllaceae), native to Eurasia, Africa, Australia, and the Pacific Islands. Members of the genus have highly branching plants that bear clusters of small white or pink flowers. Often used as a filler for bouquets and decorative floral arrangements.