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.

Pond depth: 5 - 15cm

Light: Full sun

Hardiness: Hardy

Height and spread: 40 - 80cm tall, 30 - 50cm wide

Planting and flowering months are shown in the calendar under the photos.

Bare root (7 cm, 9 cm, 1 litre, 3 litre): plants sent without a pot or compost, ready to plant straight away. The most economical way to plant a group.

Potted (9 cm, 1 litre, 3 litre): plants growing in our recycled, peat-free compost made in Lincolnshire. Larger sizes give a faster display.

Pack of 3 (7 cm bare-root, 9 cm bare-root, 1 litre bare-root, 3 litre bare-root): three plants of the chosen size at a lower price per plant.

2x Pot & Compost: two plants supplied with pots and compost.

Sizes shown with a line through them are currently unavailable.

At Lincs Plants, we strive to provide fast and reliable shipping to ensure your plants arrive in perfect condition. We offer 1-3 day shipping through a variety of dispatch methods to suit your needs.

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