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Pontederia spp.

pickerel weeds

Pontederiaceae The Americas

Attracts Pollinators Attracts Butterflies Container Friendly

Native to North America

SunFull Sun – Part Shade

WaterHigh

HardinessZones 3–10

Overview

Pontederia spp. is a genus of about six species of aquatic and marginal perennials in the family Pontederiaceae, native chiefly to the Americas. The genus includes both rooted emergent species such as P. cordata, the common pickerelweed, and free-floating species formerly placed in Eichhornia spp., including the water hyacinth P. crassipes. Emergent species grow from creeping rhizomes in shallow water and form clumps 0.3-1.2 m (1-4 ft) tall and 0.4-0.8 m (16-32 in) wide. The leaves are glossy, lance- to heart-shaped, 8-25 cm (3-10 in) long, held above the water on fleshy stalks. From summer into early autumn, dense spikes carry many small funnel-shaped flowers, most often violet-blue but ranging to lavender and white. The flowers are followed by starchy, edible nutlets. Several species spread aggressively: the floating P. crassipes is a serious aquatic weed and is banned or regulated in many regions. Even rooted species can choke small ponds, so they are often grown in baskets or lined margins to limit their spread.

Native Range

Pontederia spp. is native mainly to the Americas, from Canada through the United States to South America, growing along pond edges, marshes, slow streams, and ditches; some species have naturalized on other continents.

Suggested Uses

Grown in pond margins, water gardens, bog gardens, and constructed wetlands for water filtration and wildlife habitat. The flowers draw bees and butterflies, and the seeds and foliage feed waterfowl and aquatic life. Rooted plants are set in aquatic baskets spaced 0.4-0.6 m (16-24 in) apart in shallow water.

How to Identify

Recognized as an emergent or floating aquatic with glossy, lance- to heart-shaped leaves and dense spikes of small funnel-shaped flowers, usually violet-blue, each marked with a yellow spot. Rooted species rise from creeping rhizomes in shallow water; floating species form rosettes with swollen, spongy leaf stalks. The six-lobed flowers and aquatic habit set the genus apart.

Appearance

Size & Dimensions

Height1' - 4'

Width/Spread1'4" - 2'8"

Reaches mature size in approximately 2 years

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~12 weeks

Summer Fall

Spikes appear through summer and into early autumn, with individual flowers lasting a day and the spike blooming over several weeks. In frost-free climates the floating species flower for much of the year. Bloom is heaviest in full sun and warm, still water.

Detailed Descriptions

Flower Description

violet-blue to lavender, some white

Foliage Description

glossy green

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 Range6.0 - 7.5(Neutral)

357912

Soil Types

clay loam silt

Drainagewet

Water & Climate

Water Needs

High

Time to Maturity

1-2 years to flowering clump

Care & Maintenance

Care Guide

Most species grow in full sun in still or slow-moving fresh water, rooted in mud at the margin or floating on the surface. Rooted species hold in water 5-30 cm (2-12 in) deep over a loam or clay-rich substrate at a near-neutral pH. P. cordata is hardy in USDA zones 3-10 and overwinters as a dormant rhizome below the ice line, while the floating species are frost-tender and die at the first hard freeze. Growth is rapid through the warm season, and colonies need regular thinning to keep open water. Plants are largely free of pests but can be grazed by waterfowl and aquatic snails.

Pruning

Spent flower spikes and yellowing leaves are removed at the waterline through the growing season. Rhizomes are lifted and divided in spring to control clump size and renew growth. Floating colonies are skimmed off regularly to keep them from covering the water surface.

Pruning Schedule

spring