11. Hydrastis
L.
One species,
eastern North America.
Hydrastis appears to be a relatively early
divergent, extant member of the Ranunculaceae lineage, a hypothesis supported
by the available molecular data (Johansson and Jensen, 1993; Hoot, 1995). The
genus has retained a number of anatomical features considered primitive within
the family, as well as having flowers with 3 perianth parts. Some botanists
have therefore considered it to represent a separate family intermediate
between the Ranunculaceae and Berberidaceae (Tobe and Keating, 1985). Keener
(1993) has argued convincingly for its continued inclusion in the
Ranunculaceae. As this appears to be a case largely of lumpers vs. splitters,
the traditional treatment of the genus in the Ranunculaceae is maintained in
the present work.