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Hydrocotyle spp.

water pennyworts

Araliaceae

Cosmopolitan; wet habitats worldwide

Attracts Pollinators Container Friendly

Native to North America

SunFull Sun – Part Shade

WaterHigh

Overview

Hydrocotyle spp. is a genus of about 130 species of low, creeping perennial herbs in the family Araliaceae, found in wet and damp habitats across much of the world. Plants spread by slender, rooting stems that form mats over mud, shallow water, and moist ground, rooting at the nodes as they go. The leaves are the main feature: rounded to kidney-shaped, 0.4 to 3 inches (1 to 8 cm) across, with the stalk joined at or near the centre in many species, giving a small umbrella or coin shape. Tiny white, greenish, or pale yellow flowers are carried in small flat or rounded clusters, often hidden among the leaves. Each forms a small flattened fruit. Several species, including H. ranunculoides and H. vulgaris, grow in ponds, ditches, and marshes, and a few are aggressive aquatic weeds that choke waterways outside their native range. H. tripartita and others are grown as carpeting plants in aquariums and damp terrariums. The genus needs constant moisture and grows quickly, so it spreads readily where conditions suit it.

Native Range

Cosmopolitan, with species native to the Americas, Europe, Africa, Asia, and Australasia, wherever damp ground and shallow water occur. H. vulgaris is European, while many species are native to the Americas and Australia.

Suggested Uses

Grown as ground cover for pond margins and bog gardens, as a carpeting plant in aquariums and paludariums, and for erosion control on wet banks. The dense mats stabilize muddy edges. Native species support a range of small aquatic wildlife.

How to Identify

Recognized by creeping stems that root at the nodes and rounded to kidney-shaped leaves, the stalk often joined near the leaf centre to give a small umbrella shape. The flowers are tiny and clustered, easily missed among the leaves. The plants form low mats over wet ground and shallow water.

Appearance

Size & Dimensions

Height1" - 6"

Width/Spread1' - 4'

Colors

Flower Colors

white

green

Foliage Colors

green

Bloom Information

Bloom Period

~12 weeks

Spring Summer Fall

Flowering occurs through the warmer months, generally May to September in temperate areas and much of the year in the tropics. The small greenish-white flower clusters are inconspicuous. Most spread far more by creeping stems than by seed.

Detailed Descriptions

Flower Description

white to greenish

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.5(Neutral)

357912

Soil Types

loam silt clay

Drainagewet

Water & Climate

Water Needs

High

Care & Maintenance

Care Guide

Hydrocotyle spp. species need constant moisture and grow in full sun to partial shade on wet soil, in shallow water, or fully submerged depending on the species. They root at every node and spread quickly, forming dense mats that can crowd out other plants. Soil pH from 5.5 to 7.5 is acceptable, and most tolerate a range of water conditions. In ponds and aquariums growth is rapid and may need regular thinning. Several species are listed as invasive where they escape, so containment matters in and near natural water.

Pruning

Trimming or thinning the mats keeps the plants within bounds and stops them smothering neighbours. Runners are pulled or cut back where spread is unwanted. In aquariums the carpet is trimmed regularly to keep it low and dense.