Lobelia herb is a common weed that grows wild in North America. Lobelia herb has been recommended for asthma treatment although I cannot find any specific research. Much still needs to be learned regarding the use of lobelia before it can be widely consumed as a medicinal herb.

How is Lobelia available?
Lobelia herb extract is sold over the counter in health food stores or the internet. Most commonly lobelia is available as a 4 to 1 extract. You can also find lobelia as a bulk powder.

Lobelia Plant
There are many varieties of lobelia plant. Many species are grown in English gardens since the lobelia flower is quite attractive. Lobelia flower comes in shades of scarlet, purple, and blue lobelia.
Lobelia cardinalis
Lobelia Dortmanna grows in England
Lobelia erinus
Lobelia inflata - Lobeline (alpha-lobeline) is a lipophilic, nonpyridine, naturally occurring alkaloid obtained from Indian tobacco, Lobelia inflata. lobeline inhibits catecholamine secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors.
Lobelia laxiflora plant
Lobelia Urens grows in the UK

Lobelia Herb Research
A novel mechanism of action and potential use for lobeline as a treatment for psychostimulant abuse.
Biochem Pharmacol. 2002 Jan 15;63(2):89-98. Dwoskin LP, Crooks PA.College of Pharmacy, University of Kentucky, Lexington, KY
Lobeline, an alkaloidal constituent of Lobelia inflata LINN., has a long history of therapeutic usage ranging from emetic and respiratory stimulant to tobacco smoking cessation agent. Although classified as both an agonist and an antagonist at nicotinic receptors, lobeline has no structural resemblance to nicotine, and structure--function relationships do not suggest a common pharmacophore. Lobeline inhibits nicotine-evoked dopamine release and [3H]nicotine binding, thus acting as a potent antagonist at both alpha3beta2(*) and alpha4beta2(*) neuronal nicotinic receptor subtypes. However, lobeline does not release dopamine from its presynaptic terminal, but appears to induce the metabolism of dopamine intraneuronally. Reevaluation of the mechanism by which lobeline alters dopamine function reveals that its primary mechanism is inhibition of dopamine uptake and promotion of dopamine release from the storage vesicles within the presynaptic terminal, via an interaction with the tetrabenazine-binding site on the vesicular monoamine transporter (VMAT2). Thus, lobeline appears to perturb the fundamental mechanisms of dopamine storage and release. Based on its neurochemical mechanism, the ability of lobeline to functionally antagonize the neurochemical and behavioral effects of the psychostimulants amphetamine and methamphetamine was examined. Lobeline was found to inhibit the amphetamine-induced release of dopamine in vitro, and amphetamine-induced hyperactivity, drug discrimination, and self-administration. However, lobeline does not support self-administration in rats, suggesting a lack of addiction liability. Thus, lobeline may reduce the abuse liability of these psychostimulants.

Phytochemical study and antiinflammatory properties of Lobelia laxiflora plant.
Z Naturforsch [C]. 1998 May-Jun;53(5-6):311-7.
Three new piperidine alkaloids were isolated from stems, leaves and flowers of Lobelia laxiflora L. (Campanulaceae). The structures of racem. cis-8,10-diethyl-3,4-dehydrolobelidiol (1), racem. trans-8-ethyl-10-phenyl-3,4-dehydrolobelidiol (2) and racem. cis-8-ethyl-10-phenyl-3, 4-dehydrolobelidiol (3) were established by spectral analyses. The ability of the residues, nonalkaloid fractions, alkaloid fractions and the three alkaloids at a concentration from 0.125 to 1.0 mg ml-1 to inhibit complement activation and thus to prevent inflammatory process was estimated in vitro in human serum via both pathways. All of them inhibited complement activity with a predominant action on CP.

Pharmacological properties of beta-amyrin palmitate, a novel centrally acting compound, isolated from Lobelia inflata leaves.
J Pharm Pharmacol. 1993 Jun;45(6):545-50.
Effects of beta-amyrin palmitate isolated from the leaves of Lobelia inflata were studied on the central nervous system of mice and were compared with those of antidepressant drugs, mianserin and imipramine. In the forced swimming test, beta-amyrin palmitate, like mianserin and imipramine, reduced the duration of immobility of mice significantly in a dose-dependent manner. These results suggest that beta-amyrin palmitate has similar properties in some respects to mianserin and might possess a sedative action.

Other species of lobelia flower or lobelia plant include lobelia cardinalis, lobelia erinus, lobelia siphilitica, lobelia chinensis

Lobelia Questions
Q. Can lobelia be used with sex products and herbs such as maca, hormy goat weed, catuaba, or yohimbe?
     A. Caution is advised when using lobelia with supplements that have a stimulatory nature.