Yellow, 2-lipped, spurred flowers in a terminal cluster on a leafy stem.

About 1 " long; sepals 5; upper corolla lip 2-lobed; lower corolla lip 3-lobed, with orange ridges and a prominent spur at base; stamens 4; pistil 1, with a green style.

1-2 1/2" long, gray-green; upper ones alternate, linear, grass-like; lower ones opposite or whorled.

Capsule.

1-3'.

May-October.

Dry fields, waste places, and roadsides.

This weedy European introduction is now naturalized over much of North America. It grows from creeping roots and can form small to large colonies, thriving in dry sites. In Virginia and several western states it is considered a noxious weed. An orange path on the corolla's lower lip leads to nectar contained in the long spur and serves as a "honey guide" for insects. Experiments with hawk moth indicate that the moth will try to stick their proboscises into flowers pressed between glass; marks on the glass coincide with the orange honey guide. Even a honey guide excised and placed on other flowers will attract the moths. The name toadflax refers to the opening of the corolla, which looks like the mouth of a toad, and to the leaves, which resemble those of flax (linum). The common name Butter-and-eggs alludes to the color combination of the corolla. Dalmatian Toadflax resembles a larger version of Butter-and-eggs, with ovate or lanceolate leaves and flowers to 1 3/4" long; it is increasingly common across Canada and the northeastern and western United States and is considered a noxious weed in at least nine western states.