Dasistoma is a small genus of flowering plants in the broomrape family, Orobanchaceae, within the order Lamiales. It was described by Constantine Samuel Rafinesque in 1819. Taxonomically it sits in the tribe Buchnereae alongside other hemiparasitic genera in the family, and GBIF's backbone lists a handful of historical names under it, though only Dasistoma macrophyllum is currently treated as unambiguously accepted — the genus is effectively monotypic, represented by a single well-recognized species commonly known as mullein foxglove (also spelled Dasistoma macrophylla in some sources).
The genus is native to the eastern United States, where it occurs almost exclusively west of the Appalachian Mountains. It favors dry to dry-mesic woodlands and bluffs, typically on calcareous (limestone-derived) substrates, and is considered a moderately conservative species — that is, an indicator more often found in relatively undisturbed native plant communities than in heavily disturbed ground.
Like many members of Orobanchaceae, Dasistoma is hemiparasitic, meaning it photosynthesizes on its own but also draws water and nutrients from the roots of neighboring host plants. It grows as a tall forb, reaching around six feet in height, and is short-lived — typically completing its life cycle as an annual or biennial, though occasionally persisting as a perennial. In summer it produces tubular yellow flowers characteristic of the broomrape family's showier hemiparasitic genera.
Distribution
Dasistoma is native to the eastern United States, occurring almost exclusively west of the Appalachian Mountains.
Ecology
As a hemiparasite in the broomrape family, Dasistoma draws some resources from host plant roots while still photosynthesizing. It grows in dry or dry-mesic woodlands and bluffs on calcareous substrates, and is considered a moderately conservative species, generally absent from highly disturbed habitats.
Taxonomy Notes
Dasistoma Raf. (1819) is placed in the broomrape family, Orobanchaceae, order Lamiales. It is treated as a monotypic genus, with Dasistoma macrophyllum (Nutt.) Raf. as its sole accepted species (rendered "Dasistoma macrophylla" in some sources); GBIF's backbone additionally lists Dasistoma laevigatum and two doubtful names (D. bignoniiflora, D. brachycarpa), but current consensus recognizes only the one species.
