Yellow Toadflax

yellow toadflax plant

Yellow Toadflax

Linaria vulgaris

Colorado List B - Control required in Jefferson County

Information Sheet (pdf)


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.

Treatment Timeline


JanFebMarAprMayJuneJulyAugSeptOctNovDec
Control











RemovalNot recommended - root fragments will regrow
Herbicide











Growth











Vegetative











Flowering











Seed