Thelypteris palustris - Marsh Fern

Thelypteris palustris, commonly known as Marsh Fern, is a botanical species with deciduous foliage, perfectly adapted to wet, marshy or flooded areas, which will also grow as a slightly submerged aquatic plant. It forms beautiful fronds of bright green, finely divided, clustered in a bushy tuft. This fern with trailing rhizomes never becomes invasive. It looks stunning near water features, planted in groups, in partial shade or even in full sun. It is undemanding and very hardy, it appreciates clay soil, prefers acidic soils but tolerates limestone.

The Marsh Fern, is a plant with black, slender and trailing rhizomes native to the temperate Northern Hemisphere, where it grows in particular in marshes and damp woods, especially in peat areas, near alders. This plant belongs to the family of Thelypteridaceae. The plant has a bushy habit, with fronds arranged in a crown-like display, emerging from the ground in spring and reaching a minimum height of 40 to 80 cm (16 to 32in) and a width of 1m (3ft). Its 50 cm (20in) long rhizomes produce numerous stolons, allowing the plant to spread laterally by producing new fronds that emerge individually and not in a crown, as is often the case with ferns. The new 'croziers' (the characteristic curled shoots of ferns) emerge from the ground as early as April. They unfurl into large sterile fronds, 80 cm (32in) long and 20 cm (8in) wide, glabrous, bipinnate with long petioles. The lobes of the pinnae are entire, slightly curled towards the lower surface. Their colour is a very bright light green. The fertile fronds, narrower in shape, emerge from the rhizome about 6 weeks later. They bear small brown spore sacs (called sorus), which dust the plant with brown powder when they release spores at maturity, in late summer or autumn.

Thelypteris is an easy fern to grow as long as the soil remains constantly moist, even if it is heavy and clay, or slightly limestone. Planted in groups, it shines near a stream, or even submerged under 10 cm (4in) of water with Saururus cernuus and Typha laxmanii (narrowleaf cattail) on the edge of an ornamental pond. The miracle of its croziers emerging from the ground always intrigues and will amuse children. The fronds unfurl into large ostrich feathers.  It can be accompanied by loosestrifes, helxines, marsh marigolds or columbines in loose and moist soil, or even by willowherbs and vernonias in sunny locations. It can also be associated with Japanese primroses and Spanish bluebells that self-seed among its rhizomes.