Jubata Grass
Cortaderia jubata
Washington State Classification
Class C — Widespread, County-Selected Control
Jubata grass looks very similar to pampas grass, which is the showier of the two species and is more often planted in landscapes.
Quick Reference
Identification
Growth Habit
It is a large perennial grass that grows in basal clumps of long narrow leaves. Flowering stems grow upward, generally at least twice as long as the tussock. Plumes of flowers bloom at stem tips and range in color from deep violet to pinkish to creamy white. All flowers are female and can form seed without pollination.
Leaves
Leaves are long and narrow, generally up to 6.6 ft long by 0.8 to 1.2 inches wide. Upper and lower blade surfaces are typically hairless, though occasionally have hairs near the collar on the upper surface. Leaf margins are scabrous and sharp--easily cutting skin. Leaf sheaths are densely hairy.
Flowers
Its inflorescence is a dense panicle, commonly referred to as a plume or plume-like, and occurs at stem tips. Inflorescences range in length from 1 to 3 feet, are deep violet when immature and then pinkish turning creamy white or tan at maturity. All florets are female.
Fruit & Seeds
The fruit is a caryopsis (a dry, one-seeded fruit), to 2.5 mm in size. Seed counts on jubata grass plumes found a range of 34,000 to 122,000 seeds produced per inflorescence.
Impact
Jubata grass looks very similar to pampas grass, which is the showier of the two species and is more often planted in landscapes. Jubata grass is occasionally used as an ornamental and is listed as a noxious weed in California and Oregon. Large infestations occur along the coast in California and parts of Oregon and is documented in Washington. In 2014, escaped populations of pampas grass were discovered in Washington. Due to the similarity in appearance of jubata and pampas grass, and that jubata grass is a listed noxious weed in nearby states, it is also listed as a noxious weed in Washington.
Ecology & Spread
Habitat
It is commonly found along the California coast, growing in areas with a strong marine influence that provides cool, wet winters with little frost and moderate summer temperatures (Drewitz and DiTomaso 2004). It grows in a variety of habitats including disturbed open areas such as roadside cuts, ditch banks, forest clearcuts, mudslides or burned areas. Please click here to see a county level distribution map for jubata grass in Washington.
Spread Mechanisms
Reproduction
Reproduction is by asexual means only. Although all plants produce only female flowers, viable seeds develop from unfertilized flowers, so pollination isn’t necessary. Seeds are very small and are thought to not last long in the soil seedbank.
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Control Methods
Biological Control
- There are no approved biological control agents for pampas grass.