Ventenata
Ventenata dubia
Washington State Classification
Class C — Widespread, County-Selected Control
Ventenata dubia is a nonnative, invasive, annual grass that has rapidly expanded in perennial grass systems, in disturbed areas and managed areas in the past two decades throughout the Pacific Northwest.
Quick Reference
Identification
Growth Habit
Ventenata is a basally branched, tufted winter annual grass that has rolled or folded leaves and membranous ligules. Openly branched panicles are pyramidal in overall shape and have spikelets comprised of typically 3 florets. The awns of some of the florets are bent and twisted. Nodes are reddish-black in late spring.
Leaves
Ventenata dubia leaves mostly occur on the lower half of the stem and have open leaf sheaths. Leaves have glabrous, membranous ligules that are obtuse, usually lacerate (cut into narrow segments).. The leaf blades are 1 to 3 mm wide and 2 to 7 cm (occasionally to 12 cm) long, usually glabrous (smooth and hairless) on the upper surface, scabrous on the lower surface, starting out flat and becoming rolled or folded.
Flowers
Ventenata dubia’s inflorescence is an open panicle, pyramidal in shape, and up to 16” long. The panicle is light yellow in color and has a sheen. Panicle branches are spreading to drooping. Spikelets on pedicels contain on average 3 florets. Because of where the spikelets disarticulate, on mature specimens the straight-awned floret remains, while the bisexual florets with bent awns have broken away
Fruit & Seeds
The fruit is a caryopsis (a dry, one-seeded fruit) that is glabrous and about 3 mm long.
Impact
Ventenata dubia is a nonnative, invasive, annual grass that has rapidly expanded in perennial grass systems, in disturbed areas and managed areas in the past two decades throughout the Pacific Northwest. Ventenata dubia is increasingly becoming a problem in managed grass-hay systems where infestations can cause yield reductions of 50% or more within a few years. Beside hay, V. dubia can invade bluegrass, alfalfa, small grains, and other crops. Besides displacing desirable forage, Ventenata dubia contains silica (~2.7%), making it a poor forage plant where animals, including cattle, will not graze once inflorescences have formed. Ventenata dubia is also invading native Palouse Prairie, a threatened habitat in the intermountain Pacific Northwest, remnants of which are located in eastern Washington and northern Idaho. Ventenata dubia’s shallow root system may also cause soil to be prone to erosion and over time, it can lead to decline of productivity and land condition.
Ecology & Spread
Habitat
Ventenata dubia grows in a variety of dry, open and often disturbed habitats, tending to prefer sites that are inundated in early spring but dried out by late spring. It is commonly found on south-facing hillsides with shallow, rocky clay or clay-loam soils though it can be found on other aspects and substrates. Click here to see a county level distribution map of ventenata in Washington.
Spread Mechanisms
Reproduction
Ventenata is an annual grass that reproduces by seeds. Seed production is as high as 35 seeds per plant. Seeds persist in the seedbank for only a couple of years. Seed dispersal is assisted by the bent, twisted awns which "self bury" the seeds into soil and by hay harvest, which commonly occurs when more V. dubia seeds are present.
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Control Methods
Biological Control
- There are no approved biological control agents for Ventenata dubia.