Quaking grasses, or cowquakes, belong to a group of grasses in the plant genus Briza. Quaking-grass usually refers to all plants in this genus, but some people use this name for specific species within the genus. Some examples are big quaking grass, common quaking grass, and little quaking grass. Quaking-grass gets its name from the fact that its spikelets tremble in light breezes, inspiring the alternate name trembling grass for common quaking-grass.
Most of these grasses are native grasses in temperate regions of southwestern and western Asia, Europe, and parts of the Mediterranean. Some quaking-grass plants are hardy to USDA hardiness zone 4. A buyer needs to research which species might survive in his or her garden region.
Small or little quaking-grass is Briza minor. Often it grows to 18 inches (about 45 cm) tall and spreads to a width of about 10 inches (about 2.5 cm), which is a typical size for many Briza grasses. It is an erect plant that is loosely tufted, meaning that a cluster of short-stalked stems grow from a single of common point. Most of these grasses are tufted, either loosely or densely.
Big quaking-grass, sometimes called puffed wheat, may reach heights of 18 to 24 inches (about 45 to 60 cm) and has green, heart-shaped spikelets that are up to 0.5 inches (about 1.5 cm) long. Spikelets are a small composition of flowers that are on a single stem. Some grass flowers are stemless and lie tight against the stem, resembling a rattlesnake's tail. Other species have flowers that grow on panicles or racemes, which are flowers that are branched from the main stem. Generally, the Briza flowers are inconspicuous or not showy.
Some of the leaves and spikelets may be green, purplish, or blue-green before maturing to the straw color. The puffed wheat, or big quaking grass, usually produces reddish tinged leaves, and its cereal-shaped flowers dangle from approximately 4-inch (about 10-cm) hair-fine stalks. Sometimes this species' approximately 0.5-inch (about 1.5-cm) spikelets are a golden straw color with a cap of red where the stem attaches.
Gardeners find that the grasses usually add an unusual element to flower gardens. The long, linear leaves typically turn to neutral beige or straw color in the fall, which often contrasts with the colorful flowers and foliage in the garden. The slender, hair-like stems that bear the flowers and seeds wave and dance in the slightest wind, giving a graceful movement to the garden area. Many growers raise the grasses for adding interest to cut flower arrangements. Frequently, florists dye the grasses for extra color.
Most gardeners propagate the annual quaking-grass by seed and the perennial species by division. Often landscapers or gardeners sow the quaking-grass for borders, specimen plants, or container plants. The smaller species and cultivars sometimes adorn rock gardens.