© Jeff Skrentny, some rights reserved (CC-BY-NC) · iNaturalist
Butomus spp.
Overview
Butomus is a genus of rush-like emergent aquatic perennials in the family Butomaceae, with a single widely recognised species, B. umbellatus, native to Europe and temperate Asia. It grows from a creeping rhizome in shallow water and wet mud at pond and stream margins, sending up narrow, three-sided leaves 20-40 in (50-100 cm) long that are often twisted toward the tip. In summer a tall, leafless stem rises above the foliage, topped by a rounded umbel of pink to rose flowers, each about 1 in (2.5 cm) across with three petals and three petal-like sepals. The plant spreads by rhizome and by small bulbils, forming colonies along water edges. Outside its native range, particularly in North America, it has naturalised and is listed as an invasive aquatic weed that crowds out native marsh plants. In cultivation it grows in full sun at the edge of ponds or in containers standing in shallow water, in rich soil, and tolerates frost, dying back to the rhizome in winter.
Native Range
Butomus is native to Europe and temperate Asia, across a broad band from the British Isles to Siberia and western China. It grows in shallow still or slow-moving fresh water and wet mud along pond, lake, ditch, and river margins. It is naturalised and invasive in parts of North America.Suggested Uses
Grown as a marginal plant in ornamental ponds, water gardens, and large containers standing in shallow water, where its pink summer umbels rise above rush-like leaves. Suited to wildlife and bog-garden edges in its native range. Confined ponds suit it where it is a listed weed.How to Identify
Appearance
Size & Dimensions
Height2' - 4'
Width/Spread1' - 2'
Bloom Information
Pink to rose flowers open in summer, mainly June to August, in a rounded terminal umbel on a tall leafless stem. Each flower has three petals and three petal-like sepals. Flowering is followed by clusters of small beaked fruits, and the plant also spreads by bulbils.
Detailed Descriptions
Flower Description
pink to roseFoliage Description
green to bronze-greenGrowing Conditions
Sun Requirements
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
Care & Maintenance
Care Guide
Grow in full sun at the margin of a pond or in a container standing in 2-6 in (5-15 cm) of water, in heavy, fertile soil. Steady water and rich soil support strong flowering and leaf growth. The plant dies back to the rhizome in winter and reshoots in spring, tolerating hard frost. Lift and divide crowded clumps or remove bulbils to control spread, as the species can colonise quickly. Because it is an invasive aquatic weed in some regions, growing it in contained ponds rather than open waterways limits its escape.Pruning
Cut back faded flower stems to limit self-seeding and bulbil spread. Remove yellowing foliage in autumn as the plant dies down. Divide congested rhizomes in spring to keep clumps vigorous.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
fall
Container Growing
Suitable for container growing
Minimum container size: 5 gallons