Ravenna Grass
Tripidium ravennae
Washington State Classification
Class B — Control Required (Designated)
Ravenna grass is a large, nonnative, perennial, ornamental grass that has been recently been found escaping in eastern Washington.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
Ravenna grass is a tall, perennial grass that forms clumps of basal leaves called tussocks. Flowering stems are erect and up to 13 feet (4 meters) tall. Leaves occur on stems up to the base of the inflorescences. Stems can be reddish or other colors as flowers mature. Inflorescences are at stem tips and are slender and silvery in color.
Leaves
Its basal leaves are long and narrow, 3 to 4 feet long by 0.5 to 1 inch wide. Basal clumps of leaves can be 4 to 5 feet across. Leaves are medium gray-green and have a white midvein. The upper side at the base of the blade is densely covered with long, fuzzy tawny (tan-yellowish) hairs that typically hide the ligule and upper blade base surface. Leaves on the flowering stems are shorter and occur all the way up the stems to the base of the inflorescence.
Flowers
Inflorescences occur at stem tips and are plume-like, dense panicles, 9.8 inches to 2 feet (25 to 60 cm) long by 4 to 6 inches (10 to 15 cm) wide. Primary panicle branches are 2.4 to 7.9 inches (6 to 20 cm) and are appressed or spreading.
Fruit & Seeds
Ravenna grass has tiny seeds that are dispersed by wind and water.
Impact
Ravenna grass is a large, nonnative, perennial, ornamental grass that has been recently been found escaping in eastern Washington. It has large basal clumps of leaves that can crowd out native and desirable plant species. In Washington, seeds of Ravenna grass are spreading from ornamental plantings and can successfully germinate in a wide range of habitats, including locations near the Columbia and Yakima Rivers.
Ecology & Spread
Habitat
Ravenna grass grows in moist places such as ditches, marshes, wetlands, and riparian areas. It tolerates a wide range of conditions. In California, it was noted to be growing in much of the same type of habitat as common reed, Arundo donax, and saltcedar, Tamarix parviflora. Please click here to see a county level distribution map of Ravenna grass in Washington.
Spread Mechanisms
Reproduction
Plants can reproduce by seed and can also be propagated by plant division in early summer as it begins to emerge. Plants may not bloom in colder climates, but they do reseed themselves copiously in warmer climates
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Control Methods
Biological Control
- There are no approved biological control agents for Ravenna grass.