Description
Alisma parviflorum (now listed as Alisma subcordatum), known as American water plantain, is a North American relative of the native water plantain. It has oval, dark green leaves and, from June to September, tall, airy sprays of small white to pale pink flowers.
American water plantain at a glance
| Botanical name |
Alisma subcordatum (syn. A. parviflorum) |
| Common name |
American water plantain, southern water plantain |
| Plant type |
Clump-forming perennial; dies back in winter |
| Height and spread |
About 60 cm tall in flower (up to 90 cm), about 45 cm wide |
| Flowers |
Small, white to pale pink, in airy branching sprays, June to September |
| Position |
Full sun |
| Soil |
Mud at the margins of still or slow water |
| Pond depth |
5–15 cm of water over the crown |
| Hardiness |
Not rated by the RHS |
| Native to |
Eastern and central North America (not UK native) |
Where to plant American water plantain
- A sunny pond shelf with 5–15 cm of water over the crown
- The margins of garden ponds
- Beside native marginals for a light, airy contrast
How to plant and care for it
Plant in spring or summer in an aquatic basket. Deadhead after flowering to stop it self-seeding. As it is not native, keep it to garden ponds.
Is it poisonous?
Water plantains contain substances that are toxic if eaten, and the sap can irritate skin, so wear gloves when handling it.
Which size should I buy?
Bare-root plants (7 cm, 9 cm, 1 litre and 3 litre) arrive without a pot or compost and are the most economical way to plant a group. Potted plants (9 cm, 1 litre and 3 litre) arrive growing in our peat-free compost and give a faster display. Packs of 3 come in 7 cm, 9 cm, 1 litre and 3 litre bare-root sizes and cost less per plant. The 2x Pot & Compost option is two plants supplied with pots and compost.
