Ann. Mus. Natl. Hist. Nat. 11: 51, plate 2. 1808.
Perennials, reproducing vegetatively by adventitious buds or stolons. Fertile stems erect, (30–)60–74(–100) cm; sterile stems to 13.5 cm. Leaves of fertile stems: blade ovate to lanceolate, flat, 12–48(–65) × 3–18(–30) mm, apex acute. Racemes 1–36-flowered, dense in flower, lax in fruit; bracts ovate to lanceolate, 7–14(–20) × 2–7 mm. Pedicels erect-patent to erect, (0.5–)2–6(–15) mm in flower, 4–15(–21) mm in fruit. Calyx lobes ovate, sometimes ovate-lanceolate, 7–14 × 3.5–7 mm in flower, 7–14 × 3.5–9 mm in fruit, apex acute. Corollas pale to bright yellow, (40–)41–52 mm; tube (6–)7.5–12 mm wide, spurs straight or curved, 19–22(–23) mm, slightly shorter or subequal to rest of corolla, abaxial lip sinus 2.5–3.5(–4) mm, adaxial lip sinus 4–6 mm. Styles simple; stigma entire. Capsules globular, 6–8(–11) × 6–10.7 mm, glabrous; loculi equal. Seeds black, subtrigonous or tetrahedral, 0.9–1.5 mm, with longitudinal acute marginal ridges and anastomosed acute ridges on faces; wing absent.
Phenology: Flowering Jul–Sep.
Habitat: Roadsides, disturbed places.
Elevation: 600–2100 m.
Introduced; Colo., Idaho, Wash., se Europe, sw Asia.
Linaria grandiflora is closely related to L. dalmatica and sometimes has been included within L. dalmatica. One specimen collected in Washington (Kittitas County, west of Cle Elum, 18 June 1962, C. L. Hitchcock & C. V. Muhlick 22329, NY) exhibits discordant features (for example, pedicels 15–21 mm). According to D. A. Sutton (1988), L. grandiflora bears pedicels 0.5–4 mm, although he indicated that plants called L. pancicii Janka (which were included in the synonymy of L. grandiflora) have long pedicels. For the rest of the characteristics (corolla size, adaxial lip sinus length, calyx lobe size and shape), that specimen is fairly assimilable in L. grandiflora.