Linaria vulgaris is a perennial herb, colonial from buds along creeping roots, tap root may reach 1 m deep, reported to be associated with a vesicular-arbuscular mycorrhizae; sprouting from root buds starts in April, apparently able to fix nitrogen, (Saner et al. 1995). To 80 cm tall, often branched above.
Leaves alternate to almost opposite, linear, 2.5-6 cm long, to 0.4 cm wide, numerous, evenly distributed along stems, surface pale, blue-green.
Flowers yellow and pale orange, bilaterally symmetrical, spurred at base, 2-3 cm long including spur (Radford et al. 1968). Inflorescence indeterminate, a dense, terminal raceme; pollinated by bumblebees and halictid bees, butterflies, and flies (Mulligan and Kevan 1973; Saner et al. 1995) but also self-compatible to some extent; blooms June-Sept.
Fruit dry, rounded, 0.9-1.2 cm, opening at top to release winged seeds 0.2 cm wide, flat, brown to black; wind dispersed beginning Sept. Also dispersed by ants (Saner et al. 1995). Seeds eaten by birds and rodents (Martin et al. 1951).
Wetland status: UPL.
Frequency in NYC: Occasional.
Origin: South-eastern Europe.
Habitat: Open upland areas, roadsides, lawn edges, fill.
Notes: Linaria vulgaris has been used as a medicinal, an insecticide and as a yellow dye. Leaves contain alkaloids and iridoid glycosides, seeds contain saponins. Plant is host to Cucumber mosaic virus and broad bean wilt virus (Saner et al. 1995). Flowers are cut by nectar robbers Bombus terrestris and Vespula vulgaris. Seed capsules attacked by the beetle, Brachypterolus pulicarius which develops inside the ovary and eats buds and young stems as adults. Also attacked by a weevil, Gymnetron antirrhini, the larvae of which develop in fruit capsules. Many seeds may be infected by fungi, Alternaria sp. and Cladosporium sp. Seed germination variable often less than 50%. Seeds may also be dormant up to 8 years (Saner et al. 1995). Winter plant with pale brown, fragile capsules in terminal raceme (Levine 1995).