Small or medium-sized ferns with deltoid, oblong or strap-shaped mostly entire leaves, and linear elongate sori almost at right angles to the midrib and contiguous in pairs, one on the upper side of a veinlet, the other on the lower side of the next contiguous veinlet of the group above, the closely adjacent sori each with a narrow laterally attached indusium meeting that of the other, the double sorus thus appearing to have a common indusium opening longitudinally along its middle. [Greek name of fern.]

About 5 species, mainly of temperate regions, only the following known in North America. Type species: Asplenium Scolopendrium L.

1. Phyllitis Scolopendrium (L.) Newm. Hart's-Tongue

Fig. 56

Asplenium Scolopendrium L. Sp. PI. 1079. 1753. Scolopendrium vulgare J. E. Smith, Mem. Acad.

Turin 5: 421. 1793. Phyllitis Scolopendrium Newm. Hist. Ferns, ed.

2: 10. 1844. Scolopendrium Scolopendrium Karst. Deutsch.

Fl. 278. 1880-83.

Rootstock short, erect or ascending, chaffy with light brown scales, the leaves in a spreading crown. Stipes 2'-6' long, deciduously fibrillose-chaffy; blades simple, linear-ligulate, 7-18' long, 1'-2 1/2' broad, bright green, firm, cordate or auricled at the base, entire or lightly sinuate, usually repand; veins once or twice dichotomous near the midrib, free; pairs of sori distinct, 2"-8" long, the indusia whitish at first, soon thrust back and wholly concealed by the heavy lines of dark brown sporanges.

Shaded limestone cliffs and depressions, in central New York, near Woodstock, N. B., in Bruce and Grey Counties, Ontario, and near south Pittsburg, Tennessee. Very rare. Eurasia. Widely different forms are cultivated in Europe. Snake-fern, Sea-weed fern.

II. CAMPTOSORUS Link, Hort. Berol. 2: 69. 1833.

Slender ferns with narrow tapering simple entire or lightly sinuate leaves, bearing linear or oblong sori several times longer than boad, irregularly scattered on either side of the reticulate veins or sometimes crossing them, partly parallel to the midrib and partly oblique to it, the outer ones more or less approximate in pairs. Indusium membranous. [Greek, referring to the bent or curved sori.]

Two species, the following, which is the generic type, the other of northern Asia.

1. Camptosorus Rhizophyllus (L.) Link. Walking-Fern

Fig. 57

Asplenium rhizophylla L. Sp. PI. 1078, in part. 1753. C. rhizophyllus Link, Hort. Berol. 2: 69. 1833.

Rootstock short, usually creeping, somewhat chaffy. Stipes light green, 1'-6' long, tufted, spreading; blades evergreen, 4'-9' long, rather thin or somewhat chartaceous, simple, lanceolate, the bases usually cordate or auriculate, sometimes hastate, the basal auricles occasionally much elongate, the apex of the blade long-attenuate and usually filiform, rooting at the tip and giving rise to a new plant by the ultimate withering of the tissue, but 2-4 plants sometimes thus connected; sori usually numerous, irregularly placed.

In shaded situations, usually upon moist mossy rocks, preferring limestone, Quebec to Minnesota, Georgia, Alabama and Kansas. Ascends to 2500 ft. in Virginia. Aug.-Oct. Called also Walking-leaf.