8. Tripleurospermum Sch. Bip. (scentless chamomile)
About 40
species, nearly worldwide, but most diverse in Europe, Asia, Africa.
Species of Tripleurospermum
formerly were included in Matricaria but are accepted as a distinct
genus in many recent treatments (Bremer and Humphries, 1993; Kartesz and
Meacham, 1999; Applequist, 2002), based on such characters as solid, rounded
(vs. hollow, conical) receptacles, the presence of resin canals in the disc
corollas, and the unequally but strongly 3-ribbed fruits, as well as
differences in phytochemistry.