Austrian Fieldcress ( Rorippa austriaca (Crantz) Bess.)
Austrian fieldcress is a recently introduced invasive species in Sublette County, and early detection is critical to preventing its spread. This aggressive perennial spreads primarily through creeping roots, allowing it to form dense colonies that can outcompete desirable vegetation.
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Austrian fieldcress is an herbaceous perennial in the mustard (Brassicaceae) family. It produces erect, smooth stems that typically grow 2–4 feet tall and may branch near the top. Leaves are hairless, narrow, and oblong, and are arranged alternately along the stem. A key identifying feature is the leaf base, which clasps the stem. Leaf margins may be toothed, serrated, or deeply lobed, particularly on lower leaves.
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The plant flowers from late spring through summer, producing small yellow flowers with four petals arranged in loose clusters (racemes) at the ends of stems. Seeds form in small, globular pods and are rough, reddish-brown to black in color. However, at higher elevations with shorter growing seasons, seed production is often limited. Instead, Austrian fieldcress spreads mainly through its extensive root system, which includes both a deep taproot and creeping lateral roots.
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Its ability to reproduce vegetatively makes it especially persistent and difficult to control once established.
Quick ID
Life Cycle:
• Herbaceous perennial
• Spreads primarily by creeping lateral roots
• Also produces a deep taproot
Height:
• 2–4 feet tall
Stems:
• Erect, smooth, and hairless
• Branch near the top
• Green and slender
Leaves:
• Alternate arrangement
• Narrow and oblong
• Bases clasp the stem
• Margins toothed, serrated, or deeply lobed
• Hairless surface
Flowers (Late Spring–Summer):
• Small and yellow
• Four petals per flower
• Grow in loose clusters at the stem tips
Roots:
• Deep taproot
• Extensive creeping lateral roots
• Primary method of spread
Seeds:
• Small, rough, reddish-brown to black
• Produced in small, round pods
• Seed production is limited at higher elevations
Management Options
Prevention and early intervention are essential for effective control of Austrian fieldcress. There are currently no approved biological control agents available.
Hand pulling or digging can successfully eliminate small infestations if the entire root system—including the deep taproot and all lateral roots—is removed. Care must be taken to remove all root fragments, as remaining roots can resprout. Tillage is strongly discouraged, as it can break apart and spread reproductive root fragments, worsening the infestation.
Herbicides are often necessary for larger infestations or when manual removal is impractical. Spring applications can prevent flowering and limit spread, while fall treatments are typically more effective at targeting the root system. Always read and follow the herbicide label before application. Contact Sublette County Weed & Pest for assistance with product selection, rates, and application timing.
