yellow toadflax
(Linaria vulgaris)

Infestations    Flowers     Line Drawing     Field of yellow toadflax

New category I Montana State noxious weed.  Closely related to Dalmatian toadflax.  A problem in farm land, other states and Canada.

yellow toadflax Photo by: T. Breitenfeldt.  Location: Jefferson Co., MT.

Origin: Yellow toadflax (Linaria vulgaris), south-central Eurasia, by 1950's yellow toadflax had spread throughout North America. (1) 

Roots: Extensive root system, that spreads both down and laterally. (2)  This weed is able to spread easily through it's roots and that's the reason it is are hard to control. (5)

Stems/Leaves: Leaves are a green color with a small width, and have points at both ends. (1)

Flowers: The flowers are an bright yellow and have an orange center. When shoots grow to about 16 to 24 inches (about 40 to 60 cm) tall they begin to flower.  They flower at different times depending on the conditions.  In high elevations they could flower as late as July. (4)  They look somewhat like a garden snapdragon. (2)

Fruits and Seeds: This flower's blossom is about 1 inch in diameter.  They grow in dense clusters along the stem as it lengthens and grows.  The fruit is round, about 1/2 inch in diameter (9 to 12 mm) and a light brown, and the fruit contains many seeds.  Yellow toadflax can produce up to 30,000 seeds which can live in the soil for up to ten years but, most grow by the next year. (12)

Reproduction: It is a perennial that reproduces from seeds, and also from underground root stalks.  The seeds are spread in many ways (mostly insects) but usually just fall  close by the plant.  Yellow toadflax is able to reproduce very quickly. (12)

Life Style/Habits/Life Duration: Its usually grows in rangeland and in farm areas.  And, comes out usually in April and May. (1) Yellow toadflax grows well in wet soils and climates. (6)

Environments Favorable to Infestation: Farm lands, disturbed soils, and rangeland. (3) Overgrazed land is a perfect environment for this weed. (6)


Damage: Yellow toadflax can displace plant communities and the animal life in an area.  The seeds can be used by birds or rodents, but are not usually used by native species.  Where toadflax infests soil erosion, surface runoff, and sediment increase.  Yellow toadflax can kill the existing plant life in an area where people want to grow crops.  It also contains a poisonous glucoside that may be toxic to some animals. (7)

Control Methods: Successfully managing toadflax can take many strategies (IPM).  It is important because of environmental and genetic variability.  This means many different strategies are needed to control the weed.  Weevils and the beetle Brachypterolos pulicarius are other insects that can help control the weed.  Burning, grazing, and pulling the weed usually won't work because it doesn't kill the roots.  Chemical methods may work but usually require several treatments. (6)

Collection of Bio-Contol Agents: You can collect insects that destroy yellow toadflax  at about any infestion site by using a net and sweeping it back and forth. (1)

Purchasing Insects: You can purchase the yellow toadflax feeding insect (Brachypterolus pulicarius) at at about $75.00 for 105 adult insects, available in June. (2)

Remarks: With the infestation of yellow toadflax it is important for people to understand the risk and effects of yellow toadflax.  For more information on yellow toadflax check out the links below. (2)



    (1) Lajeunesse, Sherry Yellow & Dalmatian toadflax, [available on-line] Butte-Silverbow Weed Control Information Page, .

    (2) Breitenfeldt, Todd, Personal Interview, Whitehall Schools science teacher. E-mail:, S-mail:, Whitehall Schools, P.O. Box 1109, Whitehall, MT 59759.

    (3)TheVirtual Courthouse of Larimer County Colorado,

    (4) Beck, K.G. Biology and Management of the Toadflaxes. 23 Aug. 2004. CSU cooperate extension. 

    (6) Feb. 2006.<>.

    (5) Yellow Toadflax. 2 Feb. 2004. Stevens County Noxious Weed Control Board. 8 Feb. 2006.

    (6)  Managing Yellow and Dalmatian Toadflax. 1996. Cooperate Extension. 8 Feb. 2006.

    (7) Yellow Toadflax. 8 Feb. 2006. <>.

    (8) Yellow Toadflax Control in Direct Seeding. 1 Dec. 2004. Government of Alberta. 8 Feb. 2006.

    (9) Rice, Barry. The Global Invasive Species Initiative. The Nature Conservatory. 8 Feb. 2006.

    (10) Yellow Toadflax. 1 April 2001. Pitkin County Weed information. 6 Feb. 2006.

    (11) Serafinchon, Ada. Yellow Toadflax Control in Direct Seeding. 1 Dec. 2004. Government of Alberta. 8 Feb. 2006.

     (12) Linaria genus. California Dept. of Food and Agriculture. 2009. Sate of California. Feb. 20, 2009.

By: Taylor Olson 3/2/01.   Updated by: Abbey Adksion 2/15/06.  Updated by: Evan Gardner  2/18/09.

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