Yellow toadflax

About

Yellow toadflax is a European perennial with cheerful snapdragon-like flowers that is still sold as 'butter and eggs.' Its creeping roots form dense patches that crowd out other plants, and Colorado and Washington list it as a noxious weed.

Also called butter and eggs, common toadflax, wild snapdragon

How to identify it

Look for

Stems are 1 to 3 feet tall and packed with narrow, grass-like leaves up to about 3 inches long. Flowers look like small snapdragons, yellow with an orange throat and a long spur at the back, in clusters at the stem tips. The roots creep sideways and send up new shoots.

Look-alikes

Dalmatian toadflax (Linaria dalmatica) has similar snapdragon-like yellow flowers; ask your county weed coordinator to confirm which one you have.

Where it grows

Roadsides, trails, rail lines, field edges, rangeland, meadows and gardens, especially in Colorado, the Mountain West and northern border states.

When

Seedlings come up in April and May; plants flower from about June to September.

How it spreads

By creeping roots that can spread up to 3 feet a year (pieces under half an inch can regrow) and by seed, about 15,000 to 30,000 per plant, lasting ten years or more.

Most common in

Where it is regulated

Listed as a noxious weed in Colorado (List B) and Washington (Class C).

What to do, gentlest first

Start at the top. Weed killers are a last step; always read and follow the label.

1. Don't plant 'butter and eggs' Prevent

   Avoid buying or sharing it, clean tools and boots after working in infested areas, and plant competitive perennials or native plants.

2. Pull or dig for several years By hand

   For small patches, cut off and bag seed heads first, then pull or dig as much root as possible; follow up for several years. Repeated cultivation every week or two for two years also works in open ground.

   Mowing does not control it because it spreads by roots.

3. Toadflax insects for big stands Natural enemies

   Several approved insects, including a flower-feeding beetle (Brachypterolus pulicarius) and a seed capsule weevil (Rhinusa antirrhini), are released on large infestations by weed programs.

4. Herbicide at bloom or in fall Conventional spray

   Spray when plants begin to flower in late spring or in fall; the waxy leaves need an oil or silicone surfactant added. Products with glyphosate or dicamba are among those used.

   Read and follow the label; many lawn and brush herbicides also kill garden plants.

Uses, wildlife and pets

Pets

Not listed by the ASPCA. Occasional mild poisoning has been reported in cattle, though livestock usually avoid it.