Lamiaceae
Scutellaria lateriflora
American skullcap · Blue skullcap · Mad-dog skullcap
- Part used
- aerial
- Native range
- North America, in wet ground
- Morphology
- A slender perennial to about eighty centimetres with toothed opposite leaves and small blue two-lipped flowers borne along one side of the stem — which is what lateriflora means — each with a small cap-like protrusion on the calyx.
What is in it
Evidence
Very little controlled evidence. A small trial suggests an anxiolytic effect. The literature is confounded throughout by adulteration.
Safety
The plant itself appears well tolerated. The historical hepatotoxicity signal attached to skullcap is now substantially attributed to germander substitution rather than to this species. Confusion with Chinese skullcap, a different plant used for different purposes, is routine.
Interactions: Additive sedation with CNS depressants
Regulatory: Permitted as a listed ingredient.
Historical use
Used by Cherokee and other eastern peoples and adopted by the Eclectics as a nervine. The name mad-dog skullcap records a nineteenth-century belief that it prevented rabies, which it does not.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
American skullcap is the plant whose reputation was damaged by something else entirely, and it closes a loop this collection opened with Chinese skullcap.
Three plants share the name or the confusion: Scutellaria lateriflora from North America, Scutellaria baicalensis from China, and Teucrium chamaedrys — germander — which is neither and which was repeatedly substituted for the first in commercial supply. Germander is hepatotoxic. American skullcap, so far as anyone can tell, is not.
So the liver injury reports filed under skullcap for much of the twentieth century concern a supply chain rather than a species, and the true safety profile of S. lateriflora is still partly unknown because so little of what was studied was actually it.
That is the adulteration problem in its most complete form: it does not merely put something dangerous in the bottle, it corrupts the evidence base for the plant that should have been there.
Nomenclature verified against GBIF backbone taxonomy.