CLIMBING FERN, the botanical genus Lygodium, with 25 species, chiefly in the warmer parts of the Old World. The plants have a creeping stem, on the upper face of which is borne a row of leaves. Each leaf has a slender, stem-like axis, which twines round a support and bears leaflets at intervals; it goes on growing in definitely. Several species are favourite greenhouse plants. The American climbing fern (L. palmatum), called also Hartford fern and Windsor fern, one of the most beautiful ferns native to the United States, grows in open woods from New Hampshire to Pennsylvania and south to Florida and Tennessee.