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Crinum americanum String Lily, Swamp Lily, Seven Sisters

Edward F. Gilman, Ryan W. Klein, and Gail Hansen

Introduction

The swamp lily is a herbaceous perennial native to the southeastern U.S. that rises from a 3 to 4½ inch thick, fleshy bulb. The linear, leathery leaves grow in a rosette. These glossy leaves are bright green and reach a length of 1 to 4 feet. White or pink-striped flowers sit atop a succulent, cylindrical flower stalk that is 1 to 3 feet tall. A 6inchlong floral tube bears six petals and sepals, and rosy stamens that are tipped with yellow emerge from the throat of this tube. These striking, fragrant flowers appear in the spring, summer and fall seasons of the year. The fruits of the swamp lily are lobed seed capsules that are 1 ½ to 2 inches thick.

Full Form - Crinum americanum: String Lily, Swamp Lily, Seven Sisters
Figure 1. Full Form - Crinum americanum: String Lily, Swamp Lily, Seven Sisters
Credit: Edward F. Gilman, UF/IFAS

General Information

Scientific name: Crinum americanum

Pronunciation: KRYE-num uh-mair-rick-KAY-num

Common name(s): string lily, swamp lily, seven sisters

Family: Amaryllidaceae

Plant type: perennial; herbaceous

USDA hardiness zones: 7 through 11 (Figure 2)

Planting month for zone 7: year round

Planting month for zone 8: year round

Planting month for zone 9: year round

Planting month for zone 10 and 11: year round

Origin: native to Florida

Invasive potential: not known to be invasive

Uses: mass planting; specimen; accent

Availability: somewhat available, may have to go out of the region to find the plant

Shaded area represents potential planting range.
Figure 2. Shaded area represents potential planting range.
Credit:

Description

Height: 1 to 2 feet

Spread: 1 to 2 feet

Plant habit: spreading

Plant density: open

Growth rate: moderate

Texture: coarse

Foliage

Leaf arrangement: spiral

Leaf type: simple

Leaf margin: entire

Leaf shape: linear

Leaf venation: parallel

Leaf type and persistence: evergreen

Leaf blade length: 18 to 36 inches; more than 36 inches

Leaf color: purple or red

Fall color: no fall color change

Fall characteristic: not showy

Flower

Flower color: white; pink

Flower characteristic: year-round flowering; pleasant fragrance

Fruit

Fruit shape: round

Fruit length: 1 to 3 inches

Fruit cover: dry or hard

Fruit color: green

Fruit characteristic: showy

Trunk and Branches

Trunk/bark/branches: usually with one stem/trunk

Current year stem/twig color: not applicable

Current year stem/twig thickness: not applicable

Culture

Light requirement: plant grows in part shade/part sun

Soil tolerances: extended flooding; clay; sand; acidic; slightly alkaline; loam

Drought tolerance: moderate

Soil salt tolerances: good

Plant spacing: 24 to 36 inches

Other

Roots: not applicable

Winter interest: plant has winter interest due to unusual form, nice persistent fruits, showy winter trunk, or winter flowers

Outstanding plant: plant has outstanding ornamental features and could be planted more

Pest resistance: long-term health usually not affected by pests

Use and Management

String lily will spread quickly to form an attractive groundcover and is lovely when used as an edge or border around a pool of water. Plant them on 3 to 4 foot centers to form a solid mass effect.

This lily can be found in swamps, marshes, and river banks from Florida to Texas. However, it grows best in soils that are kept moderately moist. Plant this lily in full sun to partial shade for best growth. The swamp lily is moderately tolerant of salt spray and will grow well in coastal communities. The plant is poisonous and should not be eaten.

Swamp lily can be successfully raised from offsets or seeds.

Pests and Diseases

This plant is relatively pest free except for chewing grasshoppers.

Publication #FPS154

Release Date:October 10th, 2023

Related Collections

Part of Shrubs Fact Sheets

Related Topics

  • Critical Issue: Agricultural and Food Systems
Organism ID

About this Publication

This document is FPS154, one of a series of the Department of Environmental Horticulture, UF/IFAS Extension. Original publication date October 1999. Revised October 2023. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.

About the Authors

Edward F. Gilman, professor emeritus; Ryan W. Klein, assistant professor, arboriculture; and Gail Hansen, professor, sustainable landscape design; Department of Environmental Horticulture, UF/IFAS Extension, Gainesville, FL 32611.

Contacts

  • Gail Hansen de Chapman