Herbs, annual [perennial]; hemiparasitic. Stems erect, not fleshy, retrorsely short-strigose or glandular-hairy. Leaves cauline, opposite, sometimes some subopposite or alternate; petiole absent; blade not fleshy, not leathery, margins coarsely crenate-dentate. Inflorescences terminal, spikelike racemes; bracts present. Pedicels present; bracteoles absent. Flowers: sepals 4, calyx radially or bilaterally symmetric, not flattened laterally, tubular or campanulate, not accrescent in fruit, lobes triangular or lanceolate; petals 5, corolla white with purple galea, yellow, or red-purple, strongly bilabiate, tubular-funnelform, abaxial lobes 3, adaxial 2, adaxial lip galeate; stamens 4, didynamous, filaments glabrous, anther mucros equal or absent; staminode 0; ovary 2-locular, placentation axile; stigma clavate, capitate, or +/- 2-lobed. Capsules: dehiscence loculicidal. Seeds 150–450, white, reddish brown with age, ellipsoid or ellipsoid-oblong, wings absent. x = 12.
Introduced; Europe, introduced also in s South America, Asia, Africa, Atlantic Islands, Pacific Islands, s Australia.
Species 48 (3 in the flora).
Bellardia trixago has been included in a monospecific section of Bartsia in the broad sense (U. Molau 1990). Morphology and molecular phylogenetic analyses indicate a close relationship among Bellardia, Parentucellia, and New World species of Bartsia (A. D. Wolfe et al. 2005; J. R. Bennett and S. Mathews 2006; S. Uribe-Convers and D. C. Tank, http://2010.botanyconference.org/engine/search/index.php?func=detail&aid=685; A. Scheunert et al. 2012). Molecular phylogenetic analyses suggest that South American Bartsia are nested within a highly supported clade including Bellardia and Parentucellia (Scheunert et al.). An expanded Bellardia includes P. latifolia (Linnaeus) Caruel, P. viscosa (Linnaeus) Caruel, and the South American species of Bartsia. After this treatment had been completed, the author became aware of the alternative view presented by Uribe-Convers and Tank (2016), where all of the South American Bartsia taxa are transferred to the new genus Neobartsia Uribe-Convers & Tank, Parentucellia is recognized, and Bellardia includes only B. trixago and B. viscosa.