Alisma parviflorum - American Water Plantain, Pond Marginal Plant

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.