Dalmatian Toadflax

Linaria dalmatica ssp. dalmatica

WA B desig. Plantaginaceae
Data Maturity Baseline

Washington State Classification

Class B — Control Required (Designated)

Mature plants are strongly competitive, especially with shallow-rooted perennials and winter annuals.

Required control in Region 1 (all western Washington counties)

Quick Reference

Type
perennial herb
Origin
The Dalmatian coast of the former Yugoslavia to Romania, Bulgaria, Albania, Greece, Crete, Turkey, Azerbaijan, Syria, Iran, and Iraq.

Identification

Growth Habit

Dalmatian toadflax is a short-lived, perennial herb, 2.6 feet to 5 feet tall with light green leaves and yellow snapdragon-like flowers.

Leaves

Leaves are heart-shaped, light green and waxy. They are alternately arranged and lack petioles (leave stems) and appear to clasp the stem.

Flowers

Flowers are bright yellow, tinged with orange and resemble snapdragon flowers. The petals have 2 lips. The upper lip is 2 lobed and the lower lip is 3 lobed. Individual flowers occur on long racemes.

Fruit & Seeds

Capsules that are 0.28 to 0.31 inches long, egg to cylinder shaped with many small seeds.

Impact

Mature plants are strongly competitive, especially with shallow-rooted perennials and winter annuals. Dalmatian toadflax causes negative impacts in pastures, rangelands, and natural areas, where it outcompetes natives or other desirable species.

Ecology & Spread

Habitat

Dalmatian toadflax can be found on roadsides, in pastures, rangeland and waste areas. Please click here to see a county level distribution map of Dalmatian toadflax in Washington.

Spread Mechanisms

seed

Reproduction

Dalmatian toadflax spreads by horizontal or creeping rootstocks as well as by seed. A mature plant can produce up to 500,000 seeds.

Regional Notes — Puget Sound

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Control Methods

Mechanical

  • Hand-pulling and digging can be effective on small patches and can result in eradication if done consistently for 5-6 years.

Biological Control

  • The toadflax stem weevil, Mecinus janthinus is a biocontrol agent used in Washington state to control Dalmatian toadflax. Mecinus janthinus's larvae feed (or mine) within the plant's stems, which inhibits the transportation of nutrients, resulting in premature wilting of shoots and reduced flower production. Adults also feed on leaves and stems and can suppress plant growth. For more information about the biological control of Dalmatian toadflax, please visit WSU Extension Integrated Weed Control Project.