Images: ©Jouko Lehmuskallio
Water Lobelia
Lobelia dortmanna
- Family: Bellflower Family – Campanulaceae
- Growing form: Perennial herb. Water plant.
- Height: 20–90 (–150) cm (8–35–60 in.). Stem slender, hollow, glabrous.
- Flower: Irregular (zygomorphic), 15 mm (0.6 in.) long, pendent. Petals 5, united, pale blue to almost white, corolla bilabiate, upper lip 2-, lower 3-lobed. Sepals 5, united, calyx-lobes 2 mm long. Stamens 5. Pistil of 2 fused carpels. Inflorescence a few-flowered, one-sided raceme that lacks a terminal flower.
- Leaves: Fleshy basal leaves as a rosette. Stalkless, linear, flat on the upper side, convex on the lower. Stem leaves small.
- Fruit: A capsule with two compartments (loculi).
- Habitat: Nutrient-poor, clear lakes with sandy or gravelly bottom, at a depth of 20–150 or down to 300 cm (8–60–120 in.).
- Flowering time: July–August.
The water lobelia is an aquatic perennial with a basal leaf rosette and white roots. Its stem is scape-like, usually purplish. This species cannot grow above the water-line. Usually it occurs at depths between 20 and 150 cm, but vegetative rosettes can be encountered as deep as three metres (10 ft.). The water lobelia flowers in July or later. The flowers develop above the water surface. In addition to the seeds, the plant produces small lateral rosettes that can function as a means of dispersal.
The water lobelia thrives in poor lakes with sandy bottom. Hence it is especially common in areas with eskers and sand deposits. Anchored rosette plants and aquatic mosses are typical constituents of the flora of lakes in such regions. In the Finnish classification system of aquatic habitats, these lakes are called Lobelia-type lakes. The water lobelia is a good indicator of unpolluted water. The plant is poisonous.
