Culver's root, Blackroot, Culver’s physic
Although two to twenty species of Veronicastrum can be found in the literature, V. virginicum is the most common (Hawke, 2010).
Geographic Distribution and Habitat
V. virginicum is native to the eastern United States as well as regions of Canada including Nova Scotia, Ontario, and Manitoba (Sullivan and Kujawski, 2010). Typically, V. virginicum is found in damp, sunny areas such as near streams and in woodland settings (Lady Bird Johnson Wildflower Center), although it is sometimes also seen in wetlands (Sullivan and Kujawski, 2010).
Culver’s root is a member of the figwort family, Scrophulariaceae (Sullivan and Kujawski, 2010; USDA). It is herbaceous and 5 to 6 feet tall with green whorled foliage (Sullivan and Kujawski, 2010; USDA). The plant flowers from July to August (Rafferty and Ives, 2011). Flowers are usually white, but they can also be pink and purple (Sullivan and Kujawski, 2010). The flowers are arranged in a spike-like raceme.
Portion of the Plant Used
The root is the part of the plant that is used as an herbal remedy (Grieve, 1995; Ross, 1999).
Native Americans used the root for its properties as a laxative and emetic (Cole, 2011). They believed that the root cured typhus and “bilious” fevers, chills, diarrhea, constipation, seizures, and that it aided women in labor (Cole, 2011). V. virginicum is used to treat diarrhea and chronic dysentery (Grieve, 1995). Grieve found that the roots contain volatile oil, extractive, tannic acid, gum, resin, a crystalline principle, a saccharine principle resembling mannite, and a glucoside resembling senegin. The active component of the plant is believed to be a resin extracted from the root, using either water or alcohol, called Leptandrin (Grieve, 1995; Ross, 1999). The fresh root’s bitter taste stimulates bile production and can cause severe vomiting, but its properties are much less extreme when the root is dried (Crellin and Philpott, 1990; Grieve, 1995; Oliver, 2009).
Little scientific research has been conducted on the properties of V. virginicum and its use as an herbal medicine. An extract from a related species, V. axillare, was found to be effective in defending against ethanol-induced gastric mucosal lesions in rats (Du et al. 2013). Du et al. found that this extract may also be useful in inhibiting apoptosis and improving local microcirculation (2013).
Side Effects, Interactions, and Contraindications
Side effects include vomiting if fresh roots are ingested, and using a fresh root rather than a dried one has apparently been linked to bloody stools (Grieve, 1995). No interactions or contraindications are well-documented.