Yellow Toadflax

yellow toadflax plant

Yellow Toadflax

Linaria vulgaris

Information Sheet (PDF)


Colorado List B - Control required in Jefferson County

General

  • Family: Plantaginaceae (Plantain)
  • Has been used as an ornamental but no longer available in Colorado
  • Herbaceous perennial
  • Introduced from Eurasia


Common names

  • Wild snapdragon, butter and eggs


Habitat

  • Found in pastures, rangelands, roadsides, gravel pits and grasslands

Plant


Vegetation

  • Leaves are pale green, lance shaped; 1 to 2 inches long, one eighth to one quarter inch wide, waxy
  • Mature plants grow up to 3 feet tall
  • Produces 1 to 25 floral stems


Roots

  • Lateral roots; new plants can develop from root buds 2 to 3 weeks after germination and from root fragments as small as one quarter inch long


Flower

  • Color: yellow with orange throat; dense cluster of 15 to 20 flowers at the end of stems
  • Season: May to August
  • Size: three quarters to 1 inch long; includes a spur typically the same length as the flower


Seed

  • Each plant can produce up to 30,000 seeds
  • Seed matures from July through September
  • Viability and germination are low


Seedling

  • Early May, some fall germination possible


Reproduction

  • Mainly vegetative; also by seed


Control


Biological

  • Calophasia lunula, a defoliating moth
  • Eteobalea intermediella, a root-boring moth
  • Mecinus janthinus, a stem-boring weevil


Chemical


Cultural

  • Fertilization to promote grass cover
  • Prevention - maintain health of site
  • Removal - not effective unless done the first year plants germinate; otherwise this will fragment the roots and give rise to many more plants
  • Re-vegetation of highly disturbed sites


Mechanical

  • Burning - Not recommended; areas disturbed by fire are susceptible to invasion due to lack of competition from desirable plants
  • Grazing - Not effective; intensive grazing contributes to conditions that help spread plants; may be toxic to livestock
  • Mowing - Not recommended


More Information


Use all chemicals according to the manufacturer's label. No specific recommendation or endorsement is made or implied by listing methods or products.