Lobelia dortmanna aka Water Lobelia

Lobelia dortmanna has the common name water lobelia. It belongs to the bellflower family, Campanulaceae. It grows in water in regions with a temperate climate. Its native range spans Canada and parts of the United States. It also grows across the north and west of Europe. Britain and Ireland form part of its native range. The RHS records the Welsh name bidoglys y dŵr. Its wild sites include stony lakes and tarns with acid water.

This small plant reaches about 1 foot (0.3 metres) tall. It is a perennial: it lives for more than one year. It flowers from July to August. Each flower has both male and female organs. The supplied species sources give no flower colour or fruit details. They give no mature spread or full account of its leaves. The RHS gives flower and leaf traits for the genus only. These do not show the form of this species.

For garden use, PFAF lists full sun or light shade. It accepts sand, loam, and clay, including heavy clay soils. PFAF also lists soils that are mildly acid, neutral, or mildly alkaline. This wide soil range differs from its known acid-water habitat. It needs moist or wet ground, not a dry site. PFAF lists it as a plant for bog gardens. Its small size makes it a low-growing choice for these sites. The supplied sources give no hardiness rating or details of pests.

PFAF lists four ways to grow new plants. These are seed, division, cuttings, and layering. Sow fresh, ripe seed in a cold frame. Move young plants into their own pots once large enough to handle. Keep them in a greenhouse for their first winter. Plant them outside in late spring or early summer after frost. Divide plants in spring, or take basal cuttings then. These cuttings come from the base of the plant. Keep plenty of the stem from below ground on each cutting. Keep the potted shoots in light shade while roots form. For layering, use moist sand, where stems root at their nodes.

PFAF records no known food uses. It gives a score of zero out of five for edibility. It also lists no other material uses. The source notes use of the fresh plant as medicine. Much of its longer account of such use concerns Lobelia inflata. That is a different species; its claims should not apply to water lobelia. The hazard note draws on evidence for the genus. It does not draw on confirmed reports for this species. Thus, the supplied evidence does not show whether this plant is toxic or safe.