Stout-stemmed annual to perennial to 50 cm, glabrous except for glandular-pubescent inflorescence. Stems ascending to erect, terete or ± 4-angled, hollow. Lowest leaves petiolate, others sessile; lamina broadly ovate, to 15 x 8 cm, acute to obtuse, irregularly dentate. Racemes 3-7-flowered. Pedicels 12-25 mm. Calyx 8-15 mm, much inflated in fruit and then 10-25 x 8-15 mm, glabrous or pubescent, often tinged or dotted with red, upper tooth longer and broader than others. Corolla bright yellow, usually with red spots near throat, to 40 (-60) x 25-30 mm, with  the  mouth of the  tube  almost closed by 2 densely hairy ridges on lower lip. Capsule broadly oblong, constricted or shortly stipitate at base. Seeds finely striate.