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1 Rhizome short, erect; all the pinnae interconnected by orbicular auricles or triangular wings between the pinnae; leaf blade lanceolate, > 4× as long as wide, tapering to both ends from near the middle (the largest pinnae near the middle of the blade); primary pinnae alternate | |
2 Rachis wings present between the two basal pinna pairs; basalmost pinnae (2-) ca. 3× as long as wide; frond blade usually wider than long; rachis bearing on its lower surface relatively few, white to pale tan, narrowly lanceolate scales (these mostly 3-5 cells wide at the base) and hairs 0.1-0.25 mm long | |
3 Clones/colonies fairly compact, often dense with overlapping fronds; fronds shorter; lowermost pinnae relatively wide (ca. 4× as long as wide), often strongly deflexed and projecting forward from the plane of the upper frond; the overall shape ovate with a long-acuminate tip; spores smaller, average < 60μm; [n = 3n = 90] | |
3 Clones/colonies often loose, fronds touching but not overlapping; fronds taller; lowermost pinnae relatively narrow (4.5× or 5× as long as wide), somewhat but not strongly deflexed and not projecting as far forward; overall blade shape deltate (triangular, but again with a long tip) and less rounded at bottom; spores larger, average > 60μm; [n = 4n = 120] |
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1 Leaves pinnatifid or bipinnatifid, the pinnae not fully divided from one another (the rachis winged by leaf tissue most or all of its length). | |
4 Leaves of an herbaceous, subcoriaceous, or coriaceous texture, > 1 cell thick; sori otherwise; [various habitats, not strictly of moist sites]. | |
5 Leaf blades > 7 cm long, glabrescent or hairy with hairs < 1 mm long. | |
8 Leaves of an herbaceous, subcoriaceous, or coriaceous texture, > 1 cell thick; sori otherwise or sporangia not grouped in sori; [various habitats, not strictly of moist sites]. | |
10 Sporangia borne on the lower surface of green leaves; [collectively widespread] | |
11 Veins anastamosing (rejoining one another) to form a netlike pattern of areoles. | |
12 Costae rounded or flat on the upper side, with red, multicellular hairs; margins of segments entire or with rounded lobes | |
13 Sori on the undersurface of the leaf, marginal and more-or-less hidden beneath either the unmodified revolute leaf margin or under a modified, reflexed false indusium | |
7 Leaves bipinnate or more divided. | |
14 Leaf blade pentagonal, broadly triangular, or narrowly triangular in outline, ca. 1-2.5× as long as wide. | |
15 Leaf blade either ovate, pentagonal, or broadly triangular in outline, mostly 0.8-2× as long as wide. | |
17 Leaves monomorphic. | |
19 Leaf blade pentagonal in outline, the terminal pinna by far the largest; rhizome 5-8 mm in diameter; indusia present, thick, persistent, and reniform; [introduced species, rarely naturalized] | |
14 Leaf blade elongate, mostly lanceolate, generally > 4× as long as wide (except in Adiantum, with leaf blade often only 1.5-3× as long as wide, but not notably triangular or pentagonal in outline). | |
22 Veins ending short of the margin; indusium attached under the sorus, either cup-like (divided into 3-6 lanceolate to ovate lobes which surround the sorus from below) or of minute numerous septate hairs, which extend out from under the sorus on all sides; petioles often densely beset with scales, the petiole bases persistent |