As this is a parasitic species, all flower visits will be for nectar only.
Westrich (1989) lists the following as nectar sources: Taraxacum officinale, Cirsium, Carduus, Onopordum, Centaurea (Asteraceae) and Scabiosa (Dipsacaceae).
Celary (1989) lists the following nectar sources in Poland:
Trifolium sp., Vicia sp. (Fabaceae); Lythrum salicaria (Lythraceae); Calluna vulgaris (Ericaceae); Lamium album (Lamiaceae); Knautia arvensis (Dipsacaceae); Solidago virgaurea, Senecio vernalis,
Carduus crispus, Cirsium arvense, Centaurea scabiosa, Centaurea rhenana, Centaurea jacea, Taraxacum officinale (Asteraceae).
Ornosa & Ortiz-Sánchez (2004) list the following families of plants as providing nectar: Fabaceae, Asteraceae, Boraginaceae, Rosaceae and Scrophulariaceae.