Sometimes called “Blue Cardinal Flower” because of its strong resemblance to its close relative the Cardinal Flower, L. cardinalis, with which this species apparently hybridizes. The unattractive species name comes from an old belief that it was a treatment for syphilis. The Plant Fact Sheet (PDF) from the Natural Resources Conservation Service adds that “The Meskwaki ground up the roots of this plant and used it as an anti-divorce remedy.” What America needs today is more ground-up Lobelia siphilitica roots.
The flowers are variable in color: some are solid pale blue, some darker blue, and some—as here—strongly bicolored. A white form is found occasionally.
Like the Cardinal Flower, this Lobelia likes damp situations; this one grew on the bank of a stream in Manor, where it was blooming in early October.
Gray describes the genus and the species:
LOBELIA [Plumier] L. Calyx 5-cleft, with a short tube. Corolla with a straight tube split down on the (apparently) upper side, somewhat 2-lipped; the upper lip of 2 rather erect lobes, the lower lip spreading and 3-cleft. Two of the anthers in our species bearded at the top. Pod 2-celled, many-seeded, opening at the top. — Flowers axillary or chiefly in bracted racemes ; in summer and early autumn. (Dedicated to Matthias de l’Obel, an early Flemish herbalist.)
Flowers blue, or blue variegated with white.
Flowers rather large (corolla-tube 1-1.3 cm. long), spicate-racemose; stem leafy, 0.3-1 m. high; perennial.
Leaves ovate to lanceolate, numerous; lip of corolla glabrous.
L. siphilitica L. (GREAT LOBELIA.) Somewhat hairy; leaves thin, acute at both ends, 0.5-1.5 dm. long, irregularly serrate; flowers nearly 2.6 cm. long, pediceled, longer than the leafy bracts; corolla light blue, rarely white; calyx hirsute, the sinuses with conspicuous deflexed auricles, the short tube hemispherical. — Low grounds, Me. to Ont. westw. and southw.; rare eastw.