Brasenia spp.

Watershield

Cabombaceae

North America, Asia, Africa, and Australia

Container Friendly

Native to North America

SunFull Sun – Part Shade

WaterHigh

HardinessZones 5–10

Overview

Brasenia spp. is a genus in the family Cabombaceae containing a single widely distributed species, B. schreberi, known as watershield. It is a rooted aquatic perennial of still and slow-moving fresh water, found across North America, eastern Asia, Africa, and Australia. From a creeping rhizome in the bottom mud, long flexible stems carry floating, oval to elliptic leaves 2 to 5 inches (5 to 13 cm) long that attach to the stalk at their centre (peltate). The submerged stems, leaf stalks, and leaf undersides are coated in a thick, clear gelatinous mucilage. Small flowers, about 0.5 to 0.8 inch (12 to 20 mm) across and dull reddish-purple, are held just above the water surface in summer. Brasenia spp. grows in soft, slightly acidic water 1 to 6.5 feet (0.3 to 2 m) deep and can form extensive floating colonies. The young leaves and shoots are harvested as a vegetable in parts of East Asia. Dense colonies can crowd out other aquatic plants in nutrient-rich ponds.

Native Range

Brasenia schreberi has a broad, scattered distribution across North America, eastern Asia, sub-Saharan Africa, and eastern Australia, growing in ponds, lakes, and slow streams. It is considered native across much of this range.

Suggested Uses

Grown in natural ponds, large water gardens, and wildlife pools for its floating foliage and surface cover. The cover it casts shades the water and shelters fish and invertebrates. It is also cultivated as an edible aquatic vegetable in parts of East Asia.

How to Identify

Identify Brasenia spp. by its small, floating, oval leaves attached to the stalk at the centre, with no slit to the margin, and by the thick clear jelly that coats the stems and leaf undersides. The dull reddish-purple flowers stand just above the water on slender stalks. The central leaf attachment and gelatinous coating separate it from true water-lilies and pondweeds.

Appearance

Size & Dimensions

Height1" - 4"

Width/Spread3' - 10'

Reaches mature size in approximately 2 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~6 weeks

Summer

Flowering occurs in summer, roughly June to August, with each small reddish-purple flower opening above the water over two days before withdrawing below the surface to set seed. The display is modest and spread over several weeks. Pollination involves both wind and water.

Detailed Descriptions

Foliage Description

green, often reddish beneath

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-10 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 Range5.0 - 7.0(Neutral)

357912

Soil Types

loam silt peat

Drainagewet

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Brasenia spp. grows in full sun in still or slow fresh water 1 to 6.5 feet (0.3 to 2 m) deep, rooting into soft, slightly acidic bottom mud at a pH of 5.0 to 7.0. It establishes from rhizome divisions pressed into the substrate in spring. Soft, low-nutrient water suits it, while high nutrient loads encourage excessive spread. In temperate climates the foliage dies back over winter and regrows from the rhizome. Plants need calm water, as strong currents and heavy wave action tear the floating leaves.

Pruning

Thin spreading stems and remove surplus floating leaves through the season to keep colonies within bounds. Lift and divide congested rhizomes in spring. Clear dead foliage from the water in autumn to limit nutrient build-up.