Lobelia is a widespread, diverse genus of about 300 species. While the species found in most parts of its range, including North America, are herbs of modest size, African ?giant lobelias? include a group of fairly large trees. Lobelia inflata, one of over a dozen species native to eastern North American woodlands, is noted for its calyx, which inflates after flowering to a nearly spherical shape and conceals the fruit. Native American medical tradition used lobelia for asthma and respiratory infections, often by smoking it. It is said to have sedative effects and to induce sweating; it is also used in products that are alleged to help people quit smoking. Larger doses are emetic; lobelia was therefore a favorite herb of the Thomsonians, eighteenth-century botanical practitioners who favored an herbal counterpart to heroic medicine in which sick people were made to vomit repeatedly (from which they were called ?puke doctors? by more sensible people).

There has been almost no biomedical research involving this plant, and none of its folk uses have been scientifically confirmed. A few animal studies have identified active compounds in lobelia that have some effect on behavior and mood; one of these, lobeline, has been suggested to be a potential treatment for methamphetamine abuse, and its neurochemical effects may provide some rational basis for its traditional use for nicotine addiction. (The reported emetic effect presumably does not require randomized trials for confirmation.) Side effects that could be caused by lobeline include slowed heart rate; some literature claims that deaths have occurred from improper use, but there seem to have been no documented case reports in the last several decades. Although lobelia?s toxicity is sometimes exaggerated, it cannot be said to be safe either.

Selected References

Dwoskin, L. P., and P. A. Crooks. 2002. A novel mechanism of action and potential use for lobeline as a treatment for psychostimulant abuse. Biochem. Pharmacol. 63:89-98.

Krochmal, A., and K. Magee. 1971. A population of Lobelia inflata. Castanea 36:71-76.

McVaugh, R. 1936. Studies in the taxonomy and distribution of the eastern North American species of Lobelia. Rhodora 38: 241-263, 276-298, 305-329, 346-362.

Murata, J. 1995. A revision of infrageneric classification of Lobelia (Campanulaceae: Lobelioideae) with special reference to seed coat morphology. J. Fac. Sci. Univ. Tokyo, Bot. 15:349-371.

Rosatti, T. J. 1986. The genera of Sphenocleaceae and Campanulaceae in the southeastern United States. J. Arnold Arbor. 67:1-64.

Simons, A. M., and M. O. Johnston. 2003. Suboptimal timing of reproduction in Lobelia inflata may be a conservative bet-hedging strategy. J. Evol. Biol. 16:233-243.

Subarnas, A., T. Tadano, Y. Oshima, K. Kisara, and Y. Ohizumi. 1993. Pharmacological properties of beta-amyrin palmitate, a novel centrally acting compound, isolated from Lobelia inflata leaves. J. Pharm. Pharmacol. 45:545-550.

van der Meijden, R., and J. J. Vermeulen. 1994. Over Lobelia inflata L. en Lobelia urens L. (Campanulaceae). Gorteria 20(5-6):105-108.