Herb: Great Blue Lobelia

Latin name: Lobelia siphilitica

Synonyms: Lobelia syphyllitica

Family: Campanulaceae (Bellflower Family)

Medicinal use of Great Blue Lobelia:

The root is cathartic, diaphoretic and emetic. It is used in the treatment of dropsy, diarrhoea, stomach complaints, syphilis and dysentery. A poultice of the root has been applied to sores that are hard to heal. The leaves are analgesic and febrifuge. An infusion has been used in the treatment of colds and fevers. A poultice of the crushed leaves has been applied to the head to relieve the pain of headaches. At one time in N. America the root of this plant was believed to be effective in the treatment of VD. When used in Europe, however, it was found to be ineffective. This might have been because the N. American Indians used the fresh root (which still contained the volatile oils) and also used it in conjunction with Podophyllum peltatum and Prunus virginiana, and then dusted the ulcers with the bark of Ceanothus americanus. It was believed by some native North American Indian tribes that if the finely ground roots were secretly added to the food of an arguing couple then this would avert a divorce and they would love each other again. A homeopathic remedy is made from the roots.

Description of the plant:


100 cm
(3 1/4 foot)

August to

Habitat of the herb:

Moist woods and marshes.

Propagation of Great Blue Lobelia:

Seed - best sown as soon as it is ripe in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Division in spring. Basal cuttings in spring. Harvest the shoots when they are about 10cm long with plenty of underground stem. Pot them up into individual pots and keep them in light shade in a cold frame or greenhouse until they are rooting well. Plant them out in the summer. Layering in moist sand, it forms roots at the nodes.

Cultivation of the herb:

Moist woods and marshes.

Known hazards of Lobelia siphilitica:

The plant is potentially poisonous. It contains the alkaloid lobeline which has a similar effect upon the nervous system as nicotine.

Plant information taken from the Plants For A Future.