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Thelypteris spp.
marsh fern
Overview
Thelypteris is a large genus of terrestrial ferns in the family Thelypteridaceae, widespread across temperate and tropical wetlands, marshes, swamps, and moist woodland. Plants spread by slender, creeping rhizomes to form open colonies, sending up erect, twice-divided fronds 1-3 feet (30-90 cm) tall. The fronds are thin-textured and pale to medium green, with narrow, tapering blades; in the widely grown marsh fern, T. palustris, fertile fronds stand taller and narrower than the sterile ones. Like all ferns, plants reproduce by spores borne in small round sori on the frond undersides rather than by flowers. The creeping rhizomes can spread widely in consistently wet ground, forming dense stands that crowd smaller plants. Thelypteris needs reliably moist to wet, acidic to neutral soil and tolerates full sun where roots stay wet, though fronds scorch in dry, exposed sites. Most temperate species are deciduous, dying back after frost and unfurling fresh fronds in spring.
Native Range
Thelypteris occurs nearly worldwide in wet habitats. The marsh fern, T. palustris, is native across North America, Europe, and Asia, growing in marshes, wet meadows, swamp margins, and ditches.Suggested Uses
Used in bog gardens, pond and stream margins, rain gardens, and damp woodland where soil stays wet. Suited to naturalistic massed plantings and erosion control on saturated ground.How to Identify
Appearance
Size & Dimensions
Height1' - 3'
Width/Spread2' - 4'
Reaches mature size in approximately 3 years
Bloom Information
Thelypteris reproduces by spores and does not flower. Spores ripen on the undersides of fertile fronds through summer. New fronds unfurl in spring and the plant dies back after autumn frost in temperate climates.
Detailed Descriptions
Foliage Description
pale to medium greenGrowing Conditions
Sun Requirements
Requires 2-6 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 partial shade to full sun in reliably moist to wet, acidic to neutral soil, including bog gardens, pond margins, and damp woodland. Keep the soil from drying, as the thin fronds scorch quickly in dry ground. Contain the creeping rhizomes in smaller gardens to limit spread. Cut down old fronds in late winter before new growth. Plants are cold-hardy and die back naturally over winter.Pruning
Cut back old or frost-killed fronds to the ground in late winter before the spring flush. No other pruning is needed. Lift and divide the rhizomes in spring to control spread or propagate.Container Growing
Suitable for container growing
Minimum container size: 3 gallons