great blue lobelia (Lobelia siphilitica)
great blue lobelia
blue cardinal flower
blue cardinal lobelia
Lobelia siphilitica L. f. albiflora Britton
CONFIRMATION STATUS: Pending confirmation.
TAXONOMY: The currently accepted scientific name for great blue
lobelia is Lobelia siphilitica L. There are two varieties of Lobelia
siphilitica: 1) variety siphilitica and 2) variety ludoviciana A. DC.
Only variety siphilitica is found in the eastern United States (including
NATIVE STATUS: Native, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS:
Habit: Great blue lobelia is a native herbaceous perennial plant 1-4' tall.
It has an erect, stout stem and is unbranched, ridged, and may have short
hairs scattered along the ridges. It tends to grow vertically in shade and
can become bushier in full sun. Stems have a yellowish, milky sap when
Leaves: The alternate leaves are up to 5" long and 2" wide and, generally, lanceolate or ovate (although they can be narrowly oblong, elliptic, lance-
olate or oblanceolate), with serrated, irregular margins. Stems may be
slightly hairy. The leaves narrow to a sessile base and are without petioles.
Leaves are hairless or sparsely hairy. Leaves become smaller toward the
top of the stem.
Flowers: The central stem terminates in a long and slender raceme of light
blue to bright blue-violet flowers, the blue flowers coming out from leaf
axils near stem. The cluster is typically densely packed at the top and a bit
looser towards the bottom, with flowers blooming from the bottom up.
Sometimes plants produce white flowers, and other color variations are
possible. Each flower has 2 upper lobes (sometimes erect but usually curv-
ed back) and 3 lower lobes that flare outward from a tubular corolla that is
1-1½" long. The lower center lobe has 2 small bumps near the throat, with
a spot of white at the top of the bump, and white stripes on the outside of
the throat. The corolla has a slit on each side near the base. There is no
noticeable floral scent. The calyx is green and conspicuously hairy.
Fruit/Seeds: The seeds come in two-chambered capsules, each chamber
containing many tiny, oval, semi-translucent golden brown seeds. Seeds
are densely covered in a network of fine ridges and many shiny scale-like appendages, almost like shingles. Many capsules open at the top. The cup-
shaped capsules have an ear-lobed or auriculate base. Seeds are probably
distributed to some extent by wind or water.
Roots: The root system consists of a central taproot, from which occasion-
al basal offshoots are produced.
REGENERATION PROCESS: Great blue lobelia propogates itself by
HABITAT TYPES: Great blue lobelia habitats include moist black soil
prairies, moist meadows near rivers, floodplain forests, woodland borders,
swamps, thickets, stream banks, calcareous fens, gravelly seeps and
springs, lake borders, ditches, and moist areas of pastures. This plant
occurs in both disturbed areas and high quality habitats.
SITE CHARACTERISTICS: Great blue lobelia prefers wet to moist
soil and partial sun. Full sun is tolerated if the soil is consistently moist,
and tolerates light shade. The small seeds require light to germinate.The
soil should be fertile and loamy; it can withstand occasional flooding. It
can be found in areas with invasive shrubs growing above it and increases
in abundance in the second season following clearing of invasives.
SEASONAL DEVELOPMENT: The blooming period occurs from late
summer into fall, and lasts about 2 months.
GENERAL DISTRIBUTION: Lobelia siphilitica variety siphilitica is
naturally found in the eastern half of the United States, ranging from
Georgia north to Maine and westward to Mississippi and Arkansas north
to Minnesota (it has been recorded as far west as South Dakota). It is
not currently recorded in Rhode Island (where it may have been extirpat-
ed). Great blue lobelia has also been recorded in the Canadian province
of Ontario). Variety ludoviciana is a mid-western/Plains state variety that
extends as far west as the eastern Rocky Mountains.
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: The flowers attract bumblebees primarily.
Less common visitors include hummingbirds, butterflies, and Halictid bees.
The latter group of bees collect pollen only and are non-pollinating. Most
mammalian herbivores don't eat this plant because the foliage contains
several toxic alkaloids, chief among them being lobeline and lobelanine.
These toxic substances produce symptoms that resemble nicotine poison-
ing. However, it has been reported that deer occasionally eat this plant,
perhaps enjoying greater immunity to these toxic substances than other
animals. The seeds are too small to be of much value to birds.
The Iroquois used the plant as a cough medicine. The Meskwaki ground
up the roots of this plant and used it as an anti-divorce remedy. The mash-
ed roots were secretly put into some common dish, which was eaten by
both husband and wife. The Cherokee used a cold infusion of the roots of
great blue lobelia and cardinal flower to treat nosebleed. A poultice of the
crushed leaves of the plant was used for headache and a warm leaf infu-
sion was good for colds.
Crooked Run Valley