Thelypteris kunthii

Thelypteris kunthii is a robust deciduous botanical species of great ornamental value and easy to grow in any rich, moist soil that is not too dry in summer. Its large graceful fronds, finely cut and bright green, gather in a large clump that thickens year after year, and it spreads in colonies through its trailing rhizome. This fern is superb near water features, planted in groups, but also in woodland, in partial shade or even in full sun.

Thelypteris kunthii (synonym Christella normalis) is a plant with a trailing rhizome native to the southeastern United States. Its natural habitat consists of woodland near streams and ditches, marshy places, but the plant also grows in drier areas, in slighty moist terrain. It belongs to the family of Thelypteridaceae. This fern is deciduous, its vegetation emerges late in spring (not before April), and it dries up in late autumn. It has a bushy habit, with fronds arranged in a crown, reaching an average height of 90 cm (35in) and a minimum width of 1 m (3ft). Its 50 cm (20in) long rhizomes produce numerous stolons, allowing the plant to spread laterally by producing new fronds that emerge individually rather than in a crown, as is often the case with ferns. The new 'croziers' (the characteristic curled shoots of ferns) emerge from the ground in April. They unfurl into large sterile fronds, 90 cm (35in) long and 30 cm (12in) wide, glabrous, bipinnate with long petioles. They are a light green colour with a hint of yellow. The fertile fronds, narrower and erect, emerge from the rhizome in summer. They bear small brown spore sacs (called sori), which dust the plant with brown powder when they release spores at maturity, in late summer or autumn.

Thelypteris kunthii thrives in dark and wet areas, where few plants thrive. Once well established, this fern, which spreads into a dense colony, discourages 'weeds'. Much more decorative than the German fern, it transforms a moist woodland. Planted en masse, it is incredibly luminous near a stream, or even on the edge of an ornamental pond. The miracle of its croziers emerging from the ground always intrigues and amuses children. Its large ostrich feather-like fronds then unfurl. It can be accompanied by loosestrifes, Petasites, Begonia grandis, meadow-rues, or columbines in loose and damp soil, or even willow herb and vernonias in gentle sunlight. It can also be associated with Spanish bluebells, which will self-seed among its rhizomes.