Boston Fern, Sword Fern, Asian Sword Fern, Macho Fern, Fishtail Fern

Nephrolepis species (neph-row-LEP-us)

Ferns

            N. biserrata (Swartz) Schott, Macho Fern, Giant Sword Fern

            N. cordifolia (L.) C. Presl,  Sword Fern, Tuberous Sword Fern

            N. exaltata (L.) Schott, Boston Fern

            N. falcata (Cav.) C. Christens. forma furcans (T. Moore in Nicholson) Proctor, Fishtail Fern

            N. multiflora (Roxb.) F. M. Jarrett ex C. V. Morton, Asian Sword Fern

Explanation of names:

Nephrolepis means kidney-scale in reference to the reniform indusium.

Falcate means sickle-shaped. Furcate means forked.

Biserrate means having sawteeth with teeth on the teeth.

Cordifolia means heart-leaf.

Exaltata means tall.

Multiflora means multi-flowered, although ferns have no flowers.

Ranges: Fern spores blow worldwide, making nativity difficult to assess. The following distribution statements come from the Flora of North America: http://hua.huh.harvard.edu/FNA/

            N. biserrata. “Terrestrial or less commonly epiphytic in forested, relatively wet habitats, e.g., swamps, but occasionally thickets, roadsides, or clearings; 0 m; Fla.; Mexico; West Indies; Central America; South America; Africa; se Asia.”

            N. cordifolia. “Terrestrial or epiphytic in wet, shady places, limestone ledges, cliffs, rock, roadsides, and often old homesites or waste places; widely escaped from cultivation and only questionably native to any particular region; 0 m; Fla.; Mexico; West Indies; Central America; South America; Africa; se Asia; Pacific Islands in Hawaii.”

            N. exaltata. “Terrestrial or epiphytic in forested to open habitats, most often as an epiphyte; 0 m; Fla.; West Indies; Pacific Islands in scattered locations…Nephrolepis exaltata is occasionally found farther north in the flora, but only as an escape from cultivation. Nephrolepis exaltata is usually confused with N . cordifolia when sterile; the latter species can be distinguished by its distinctly bicolored, adaxial rachis scales. These bicolored scales will distinguish N. cordifolia from all of the other species, even in the absence of other key features… Cultivars of Nephrolepis occasionally are found in the wild, where they persist for some time. Numerous forms of N . exaltata cv. `Bostoniensis' and its derivatives are widely cultivated, and the following are known from Florida: N . exaltata cv. `Bostoniensis', N . exaltata cv. `Elegantissima' complex, N . exaltata cv. `Florida Ruffles', N . exaltata cv. `M. P. Mills'.”

            N. falcata f. furcans. “It is widely cultivated and persists when escaped; it is not known to spread from spores.” ‘Fancy Frill’ has extra-long, narrow leaflets.

            N. multiflora. Escaped in Florida (FNA)

Key to Nephrolepis Species Cultivated in South Florida

1.  Leaflets forked like fish tail…N. falcata forma furcans (Fishtail Fern)

1.  Leaflets otherwise…2

2.  Plants with tubers; leaflet veins one-forked; leaflets rounded; sori bean-shaped;

       rachis with bicolored scales on top surface …N. cordifolia (Sword Fern)

2. Plants without tubers; leaflet veins twice forked; leaflets usually pointy; sori variable; rachis with no scales or single-colored scales on top…3

3. Leaflets sometimes over 1” wide and widely separated; leaflets without a basal lobe (or this very small), leathery…N. biserrata (Macho Fern)     

3. Leaflets narrower and overlapping, with a basal lobe, herbaceous…4

4. Bases of petioles having dark brown scales, these with white margins; tops of leaflet veins fuzzy…N. multiflora (Asian Sword Fern)

4. Bases of petioles with light-colored scales; tops of leaflet veins not fuzzy… N. exaltata (Boston Fern)

Additional information: http://www.corkscrew.audubon.org/Wildlife/FernID/Pinnate.html#Boston Fern-native

Landscape uses:

            N. biserrata. Large bedding-fern for filling partiallyshaded spaces. May stand 5’tall

            N. cordifolia. Invasive exotic. Do not use. FEPPC I

Also invasive is N. multiflora which has the bases of the petioles with abundant dark brown scales having light-colored margins (vs. uniformly colored in other FL species). Its leaves are more or less pubescent, and the leaflets have long-tapered tips. The top surfaces of its pinnae are pubescent, a feature absent from the other Florida species except N. biserrata, which has distinctive stalks on the pinnae.

            N. exaltata. Found in natural areas, weedy when outdoors. Favorite indoor plant. Many cultivars.

            N. falcata f. furcans. Much-used tough, reliable, bedding plant for sun or partial shade. Although introduced, does not seem to spread by spores. Escaped a little in Palm Beach County (WU2).