35. Helminthotheca Zinn (ox-tongue)
About 5 species,
Europe, Africa.
Traditionally, Helminthotheca
has been treated as a specialized group within Picris by most authors
(Barkley, 1986; Gleason and Cronquist, 1991), but Lack (1974) demonstrated that
it is separable from that genus based primarily upon its unusual involucral
bracts and beaked achenes, as well as some micromorphological traits.
Preliminary molecular studies (Whitton et al., 1995) have placed Helminthotheca
as the most primitive member of the Picris lineage, but taxon sampling
has been far too incomplete for this conclusion to be well supported.