Dalmatian toadflax (Linaria genistifolia ssp.)
Keys to ID:
- Showy yellow snapdragon-like flowers with an orange throat.
- Thick, waxy, bluish, heart-shaped leaves that wrap the stem.
Identification:
- Lifecycle: Perennial
- Growth Form: Forb
- Flower: Loose, elongate racemes of bright yellow flowers on vertical stems resembling snapdragons. May thru Aug
- Seeds/Fruit: Fruits are egg-shaped to nearly round capsules, and contain numerous numerous small, black-brown, ridged seeds.
- Leaves: Leaves are broad, ovate, and alternate. Thick, waxy, bluish.
- Stems: A single toadflax plant may contain up to 25 flower stems. Mature plants are up to 3 feet tall (CSU 2000).
- Roots: Taproot may penetrate 3 feet. Horizontal roots may grow several yards long, and can develop adventitious buds forming independent plants.
- Propagation: Seeds and horizontal roots.
- Other: Yellow Toadflax (L. vulgaris) is similar, but has more linear pointed leaves and is generally smaller.
Control:
Mech: Hand pull, making certain to pull all the roots. Tilling can be effective if done repeatedly. The cut roots can re-sprout resulting in a larger problem if not tilled again immediately when new sprouts are coming through the soil. This may need to be repeated 3 to 4 times per season for several years to deplete the root reserves as well as the soil seed bank (Whitson 1999). Bio: Calophasia lunula, a predatory noctuid moth; Eteobalea intermediella, a root boring moth; and Mecinus janthinus, a stem boring weevil are available.