- Name also: Common Toadflax, Butter and Eggs
- Family: Plantain Family – Plantaginaceae
(formerly Figwort Family – Scrophulariaceae)
- Height: 20–70 cm (8–28 in.). Stem unbranched, sturdy, fine-haired.
- Flower: Irregular (zygomorphic). Corolla yellow, fused, bilabiate, spurred, 25–30 mm (1–1.2 in.) long. Upper lip 2-lobed; lower lip 3-lobed, base orange protuberance closing corolla tightly at base. Spur 6–12 mm (0.24–0.48 in.) long, slim. Calyx fused, 4-lobed. Stamens 4. Gynoecium fused, single-styled. Inflorescence a long, abundantly-flowered, spike-like terminal raceme.
- Leaves: Lowest opposite, upper alternate. Stalkless. Blade linear, sharp-tipped, margins revolute.
- Fruit: Almost round, 5–10 mm (0.2–0.4 in.) long capsule. Seed winged, disc-like.
- Habitat: Sandy and gravelly sea shores, rocky outcrops, roadsides, harbour areas, dry waste ground, grain fields, sown lawns, field banks. Also an ornamental and a left-over and escape from old gardens.
- Flowering time: (June–)July–September(–October).
Toadflaxes are abundant in western Asia and around the Mediterranean. Many of them favour culturally-influenced areas, at least to at least a certain extent.
Yellow toadflax is a perennial, strong-rooted herb which has root buds. It flowers on roadsides right up until late September. In Finland it is native to coastal rocky outcrops. Inland plants may be established aliens that arrived later. Yellow toadflax has a beautiful flower and has thus been transplanted into gardens as an ornamental and found new habitats in this way.
The lower lip of yellow toadflax’s special-looking corolla has two swellings which tightly seal the throat of the flower, meaning that only bumblebees and several other strong insects are able to open the flower, reach the store of nectar in the spur and pollinate the plant. The specialized flower on the one hand reduces the amount of competition between pollinators and on the other hand increases their loyalty to a single plant. Both sides make use of the fact that there is enough nectar for the plant’s rare and chosen pollinators, and the plant’s pollen goes to the right address in the form of a stigma of the same species. Actually certain hymenopterans which cannot enter the plant by the normal route bite a hole in the tip of the spur and make off with the nectar without giving anything in return.