Water poppy

Hydrocleys nymphoides

Also known as Water-poppy, Yellow water poppy

FreshwaterFloatingRunnersPlantlets

Invasive. Water poppy is invasive and regulated in parts of Australia and elsewhere. Never release into the wild; dispose of in the trash.

Water poppy (Hydrocleys nymphoides) — no rights reserved · cc0

Care at a glance

Light: High light
CO2: No CO₂ needed
Temperature: 64–82°F; 18–28°C
Max height: 11.8 in; 30 cm

Growth rate: Fast
Placement: Floating
Type: Floating
pH: 6.0–7.5
Hardness: 3–15 dGH
Spread: 39.4 in (100 cm)
Nutrient uptake: Root + water column
Growth region: Emersed
Difficulty: Easy
Family: Alismataceae
Origin: Central and South America

Overview

A marginal and floating pond plant more than a submersed aquarium plant: it wants bright light and roots in a rich substrate in shallow water, sending waxy leaves and yellow flowers to the surface. It is invasive. It is a declared or regionally regulated weed across Australia (Queensland, New South Wales and Victoria) and import is banned in several western US states, though it is not on the US federal noxious weed list. Never release it into natural waterways, and dispose of trimmings in the bin since it regrows readily from fragments.

In the wild

Native to still and slow-moving fresh water in Central and South America, where it roots in shallow mud and floats its foliage on the surface. It spreads by trailing runners that send down roots and grow new plantlets, forming dense floating mats topped with three-petalled yellow flowers.

Good to know

Hydrocleys nymphoides sits in the water-plantain family Alismataceae, not among the true water lilies its rounded floating leaves resemble. Each bloom lasts only about a day. The species reproduces largely by fragmentation and runners rather than seed, which is a big part of why it spreads so aggressively once loose.

Did you know

Did you know each cheerful yellow water poppy flower opens for just a single day before fading, so an established mat produces a steady succession of one-day blooms through the warm season.