Nephrolepis exaltata

Nephrolepis exaltata, known as the sword fern or Boston fern, is a species of fern in the family Nephrolepidaceae. It is native to the Americas. This evergreen plant can reach as high as 40–90 centimetres (16–35 in), and in extreme cases up to 1.5 metres (4 ft 11 in). It is also known as the Boston sword fern, wild Boston fern, Boston blue bell fern, tuber ladder fern, or fishbone fern.

Description

The fronds of Nephrolepis exaltata are 50–250 centimetres (20–98 in) long and 6–15 centimetres (2.4–5.9 in) broad, with alternate pinnae (the small "leaflets" on either side of the midrib), each pinna being 2–8 centimetres (0.79–3.15 in) long. The pinnae are generally deltoid, as seen in the adjacent picture. The pinnate vein pattern is also visible on these highly compound leaves. The edges appear slightly serrate, linear to lanceolate and glandular. The rachis bears monochrome sprout soups. The leaflets are entire, undestroyed and oblong-lanceolate up to 4.8 inches (120 mm) long and up to 0.9 inches (23 mm) wide. They stand at a distance of less than 1 centimetre (0.39 in). The sori are rounded. The spores are warty and wrinkled. Nephrolepis exaltata forms an underground rhizome that is slim and tuberous.

The species has erect fronds, but Nephrolepis exaltata 'Bostoniensis' (Boston fern) and 'Teddy Junior' have gracefully arching fronds. This mutation was discovered in a shipment of N. exaltata to Boston from Philadelphia in 1894. Other proposals for the origin of the term Boston fern were documented by David Fairchild, who stated that the term came from Florida pioneer nurseryman John Soar, who sent the plants to his friend in Boston.