Description of Alisma lanceolatum (Mad Dog Weed)

Alisma lanceolatum is narrow-leaved water plantain, sometimes called mad-dog weed in older texts. It’s similar to Alisma plantago-aquatica but with slimmer leaves and a slightly lighter look, making it handy for tighter margins.

Appearance

It forms a basal clump of lance-shaped leaves. In summer it produces tall branching stems with many small pale flowers, usually white to soft pink. Flowering stems often reach 60 to 100cm depending on water depth and feeding.

Care Guide

It enjoys wet mud and shallow water and copes with water levels that rise and fall.

• Sun: Full sun to light shade.
• Soil: Mud or heavy wet soil, or aquatic compost in a basket.
• Water: Shallow margins or saturated bog soil.
• Cut back: Remove old stems in autumn or spring.
• Seeding: It can self-seed in open wet ground.

If you want it to look natural, leave some stems through winter and tidy in spring.

Suitability for Bog Garden

This suits bog gardens with a wet shelf or pond edge. It gives height without heavy foliage and works well with sedges and rushes.

Place it mid-bed near the waterline so stems rise cleanly.

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