Click the number at the start of a key lead to highlight both that lead and its corresponding lead. Click again to show only the two highlighted leads. Click a third time to return to the full key with the selected leads still highlighted.
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 |
1 Rhizome long creeping; all the pinnae interconnected by a narrow rachis wing, or the proximal 1-3 pairs of pinnae free; leaf blade broadly triangular, broadest at or near the base (the largest pinnae the basal or next pair); primary pinnae opposite. |
..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 |
..2 Rachis wings absent between the two basal pinna pairs; frond blade longer than wide; basalmost pinnae 4-5× as long as wide; rachis bearing on its lower surface numerous tan to brown, lanceolate scales (these mostly 6-12 cells wide at the base) and acicular hairs 0.3-1.0 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] |
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). |
..2 Leaves pinnatifid, the pinnae not lobed. |
....3 Leaf blades with a long-attenuate apex, blade lobed for up to 2/3 its length; sori elongate |
....3 Leaves without a long-attenuate apex, blade lobed for > 4/5 of its length; sori round |
..2 Leaves bipinnatifid, at least the lowermost pinnae deeply lobed. |
......4 Leaves of a very delicate texture, 1 cell thick; sori borne in cups on the leaf margins; [rock outcrops with high air humidity] |
......4 Leaves of an herbaceous, subcoriaceous, or coriaceous texture, > 1 cell thick; sori otherwise; [various habitats, not strictly of moist sites]. |
........5 Leaf blades 1-7 cm long, hairy with some hairs > 1 mm long |
........5 Leaf blades > 7 cm long, glabrescent or hairy with hairs < 1 mm long. |
..........6 Lowermost (and other) pinnae with numerous, rather even lobes |
..........6 Lowermost pinnae with a few, irregular lobes (the upper pinnae unlobed) |
1 Leaves pinnate, pinnate-pinnatifid, 2-pinnate, or even more divided, to 5-pinnate (the rachis naked for most of its length, often winged in the apical portion). |
............ 7 Leaves pinnate or pinnate-pinnatifid. |
............ ..8 Leaves of a very delicate texture, 1 cell thick; sori borne in cups on the leaf margins; [rock outcrops with high air humidity] |
............ ..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]. |
............ ....9 Pinnae > 1 cm wide; leaves subcoriaceous to coriaceous |
............ ......10 Sporangia borne on 2 specialized fertile pinnae (in rows on segments of the 2 basalmost fertile pinnae of the leaf); [native; TX westwards] |
............ ......10 Sporangia borne on the lower surface of green leaves; [collectively widespread] |
............ ........11 Veins free; [native; s. FL] |
............ ........11 Veins anastamosing (rejoining one another) to form a netlike pattern of areoles. |
............ ..........12 Costae with a groove on the upper side, sometimes with tan, filiform scales; margins of segments denticulate, crenate, or spinulose |
............ ..........12 Costae rounded or flat on the upper side, with red, multicellular hairs; margins of segments entire or with rounded lobes |
............ ....9 Pinnae < 1 cm wide; leaves herbaceous to subcoriaceous. |
............ ............ 13 Sori on the undersurface of the leaf, located away from the margins |
............ ............ 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 narrowly triangular in outline, mostly 2-2.5× as long as wide. |
............ ............ ......16 Sporangia borne either in many sori on fertile blades or on fertile pinnules borne at the base of the otherwise sterile blades |
............ ............ ......16 Sporangia borne in a solitary sorus terminal on the truncate apex of wedge-shaped leaf segments |
............ ............ ....15 Leaf blade either ovate, pentagonal, or broadly triangular in outline, mostly 0.8-2× as long as wide. |
............ ............ ........17 Leaves dimorphic, fertile leaves with longer and narrower segments than the sterile leaves |
............ ............ ........17 Leaves monomorphic. |
............ ............ ..........18 Leaf segments strongly revolute; sporangia scattered along veins or submarginal, not grouped into indusiate sori; lower surface of leaf segments either densely covered with a whitish farina or distinctly bluish-green |
............ ............ ..........18 Leaf segments planar; sporangia borne in round, indusiate sori; lower surfaces of leaf segments green. |
............ ............ ............ 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] |
............ ............ ............ 19 Leaf blade broadly triangular in outline, the basal pinnae by far the largest; rhizome ca. 1 mm in diameter; indusia absent; [native species of mountain peaks from n. NC and VA northwards] |
............ ............ ..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). |
............ ............ ............ ..20 Sori marginal, usually more-or-less hidden under the revolute margin of the pinnule |
............ ............ ............ ..20 Sori not marginal, either exposed, or slightly to strongly hidden by indusia. |
............ ............ ............ ....21 Leaf blades 3-12 cm long; sori elongate, covered by a flap-like, entire indusium |
............ ............ ............ ....21 Leaf blades 4-30 (-50) cm long; sori globular, surrounded or covered by an entire, ciliate, or divided indusium. |
............ ............ ............ ......22 Veins reaching the margin; indusium attached under one side of the sorus, hood-like or pocket-like, arching over the sorus; petioles glabrous or sparsely beset with scales, the petiole bases not persistent |
............ ............ ............ ......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 |