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Great Blue Lobelia

Lobelia siphilitica


This perennial plant is 1-4' tall. It is erect and usually remains unbranched. The central stem is light to medium green, terete or angular, and glabrous to sparsely hairy. The alternate leaves are up to 5" long and 2" wide; they are oblanceolate, obovate, ovate, or broadly elliptic in shape, and their margins are serrated. The lower leaves clasp the central stem, while the upper leaves are sessile. The upper surfaces of leaves are medium to dark green and sparingly covered with short hairs. The central stem terminates in a spike-like raceme of flowers about ½-2' long. The flowers are 1-1½" long, angled upward, and densely distributed along the raceme. Each flower has a blue-violet corolla (rarely white) that is narrowly bell-shaped (campanulate) and 2-lipped. The upper lip has 2 slender erect lobes that curve slightly inward or backward, while the lower lip has 3 descending lobes that are oblong-lanceolate. Near the throat of the flower at the base of the lower lobes, there is a pair of small white patches. The green calyx is deeply divided into 5 linear-lanceolate teeth; it is conspicuously hairy. The calyx teeth are long and spreading. The blooming period occurs from late summer into fall, lasting about 2 months. Afterwards, the flowers are replaced by capsules containing small seeds. These seeds are probably distributed by wind or water to some extent. The root system consists of a central taproot, fromDistribution Map which occasional basal offshoots are produced.

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Spotted by

Wisconsin, USA

Spotted on Sep 6, 2015
Submitted on Oct 18, 2016

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