Dalmatian toadflax

Dalmatian toadflax is an herbaceous perennial in the Plantaginaceae (plantain), formerly Scrophulariaceae, family. It predominantly produces erect stems that may reach 3 feet tall; however, some stems may remain prostrate along the ground. Stems are woody at the base and waxy and herbaceous toward the tops. Leaves and upper stems are blue green to gray green in color. Leaves are lanceolate to heart-shaped, and they have smooth margins and are very waxy. Leaves occur alternately and clasp the stem. Dalmatian toadflax flowers from late spring to late summer. Flowers resemble snapdragon flowers and occur on racemes at the end of stems. Each flower is yellow, between ¾ and 1 ½ inches long, and has two “lips”, an upper and lower. When opened, an orange bearded throat is apparent. Flowers also have a long spur on the bottom. Dalmatian toadflax has both a taproot and lateral rhizomes. Seeds are produced in two-celled capsules and are small, black or dark brown, and irregularly shaped with or without small wings.

Dalmatian toadflax produces quinazoline alkaloids and may be poisonous to livestock; however, it is generally avoided by cattle and horses. Goats and sheep have grazed Dalmatian toadflax without apparent effect.

Dalmatian toadflax is native to Eurasia and the Mediterranean, including the historic region of Dalmatia now a part of Croatia. It was introduced to North America in 1874 as an ornamental. It creates dense infestations by spreading rhizomes and seeds and spreads to new locations by seeds and root fragments. This species is frequently found in rangeland, sagebrush steppe, disturbed sites, and cobbled areas prone to scouring from spring runoff.

Prevention and cultural control strategies should be utilized as much as possible.

There is only one biological control agent available for Dalmatian toadflax in Teton County; however, it is effective at reducing density of Dalmatian toadflax within infestations. The stem mining weevil (Mecinus janthiniformis) is widespread throughout Teton County, and assistance with collecting or releasing this biological control agent is available upon request.

When infestations are in cobble or loose soil or for small plants, hand pulling and digging out of the taproot and all lateral roots can be effective, but great care must be taken to ensure that all of the root system is removed. Tillage is strongly discouraged as this is likely to fragment and spread reproductive roots. Mowing is not recommended for control as it stimulates root and rhizome growth. Heavy control grazing with goats may be effective when combined with other control methods.

Large infestations and areas where manual removal is not practical can be controlled with herbicides. Spring treatments prevent flowering and seed production, and fall treatments may be effective at killing the root system. Read the label before using any herbicide. Contact TCWP if you have any questions about application rates or how to use an herbicide.

• Weed Report: Dalmatian toadflax (2013) DiTomaso, J.M., G.B. Kyser et al. Weed Control in Natural Areas in the Western United States. Weed Research and Information Center. University of California.
• Dalmatian Toadflax (2010) King County Noxious Weed Control Program Weed Alert.
• Dalmatian Toadflax (2024) Minnesota Department of Agriculture
• Biology and Management of the Toadflaxes (2014) Beck, K.G. Colorado State University Extension. Fact Sheet 3.114
• Field Guide for Managing Dalmatian and Yellow Toadflaxes in the Southwest (2014) United States Department of Agriculture Forest Service