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Keys to the pteridophytes of Australia


The following on-line dichotomous key for families of of Australia is a reworked interactive bracketed version of the indented dichotomous Key to the families of ferns and fern allies in Australia by P.M. McCarthy (1998) published in Flora of Australia 48: 37 - 46 by the Australian Biological Resources Study (ABRS).

This version of the key may be read an used as a traditional printed key, but it is also interactive to the extent that selectiing an option will jump to the appropriate place in the key, where the next option can be selected.

In addition, selecting the key couplet number will jump backwards to the option that lead to that selection, enabling a degree of controled backtracking to a position of confidence if a wrong choice in the keying process is suspected.

For interim comparison, each of the terminal family names links to family descriptions and keys to genera prepared for a treatment of the pteridophyte flora of Papuasia. Many of the Australian genera are included in these keys, but there are a significant number of non-Australian genera. These descriptions and keys are being updated to cover Australian taxa and to converge the taxonomy with that of the Flora of Australia treatments.

A similar working key to Papuasian pteridophyte families is available.


McCarthy, P.M. (ed.) 1998. Flora of Australia. 48. Ferns, gymnosperms and allied groups. i - xxii, 1 - 766, f. 1 - 213, maps 1- 609.

McCarthy, P.M. 1998. Key to the families of ferns and fern allies in Australia. Flora of Australia. 48: 37 - 46.

Key to Australian pteridophyte families

1 Free floating, aquatic plants... ...2
Anchored plants, usually terrrestrial, epiphytic or lithophytic... ...4
2 Sterile lamina 1 - 3-pinnate, 40 - 400 mm long, 10 - 200 mm wide... Parkeriaceae
Sterile lamina simple, paired and 7 - 30 ( - 40) mm long or crowded and 1 - 2 mm long... ...3
3 Frond of 2 foliar, floating leaves and 1 submerged, root-like sporocarp bearing leaf; floating leaves broad or rounded... Salviniaceae
Frond of numerous, crowded, ovate to triangular, bilobed leaves; spore capsules in axils of submerged leaf lobe... Azollaceae
4 Stems jointed, rush-like, sometimes hollow; leaves small, whorled, joined in a sheath at stem nodes... Equisetaceae
Stems not jointed; leaves not whorled and joined in a sheath at stem nodes... ...5
5 Sporangia in the axil of a forked leaf, and fused in groups of 2 or 3, or in the axils of spophylls (often in cone-like structures), or in swollen leaf-bases... ...6
Sporangia free, laminal or marginal and either scattered or in clusters (which may in turn be confluent), or sporangia occurring in scattered or clusted sori, aggregated into a spike or enclosed in sesssile or stalked receptacles... ...9
6 Sporangia fused in groups of 2 or three and born in the axils of forked leaf... Psilotaceae
Sporangia solitary, in the axils of sporophylls (often in cone-like structures) or in swollen leaf bases... ...7
7 Sporangia in axils of sporophylls that are often aggregated in cone-like structures... ...8
Sporangia in swollen leaf bases on adaxial side; plants aquatic or semiaquatic... Isoetaceae
8 Sterile leaves and sporophylls with a minute basal ligule; sporangia dimorphic; megasporangia assuming the shape of the 4 developing megaspores; microsporangia globose to reniform... Selaginellaceae
Sterile leaves and sprophyllls lackng a basal ligule; sporangia uniform, subglobose to reniform... Lycopodiaceae
9 Fronds compromising a steril lamina and a fertile spike diverging from a common basal stalk... Ophioglossaceae
Sterile and fertile fronds borne separately on the rhizome or all mature fronds fertile... ...10
10 Sori completely enclosed in sessile or stalked woody spore receptacles at the base of the stipe; sterile fronds with 2 or 4 apical leaflets in oposite pairs, or leafless and consisting of a stipe only... Marsileaceae
Sori not enclosed in spore receptacles, either completely exposed or partialy protected by an indusium or reflexed leaf margin; sterile fronds simple or variously dissected, lacking apical leaflets... ...11
11 Pinnae with swollen jointed bases; sori composed a double row or ring of free sporangia, or fused in a bivalved synangium... Marattiaceae
Pinnae lacking swollen jointed bases; sori scattered or aggregated, but not composed of a double row or ring of free sporangia or fused in bivalved synangia... ...12
12 High-climbing plant; fertile and sterile pinnae markedly different; sori borne on marginal projections of pinnules... Lygodiaceae
Plants not climbing, or if climbing, sori borne on the margin on the underside of lamina, not on apices of laminal axes, nor on marginal projections... ...13
13 Sori on sort pinnate or digitate segments at apices of stipe-like, often dichotomously branching lamina axes... Schizaeaceae
Sori borne on the margin or underside of lamina, not on pinnate or digitate fertile segments at the apices of lamina axes... ...14
14 Rhizome and stipe spongy; sporangia solitary, in two marginal rows; aquatic and semiaquatic ferns... Parkeriaceae
Rhizome and stipe not spongy, sposrangia not solitary in marginal rows; mostly terrestrial, lithophytic or epiphytic ferns... ...15
15 Rhizome a single arborescent runk over c. 2 m tall; tree ferns... ...16
Rhizome not an arborescent trunk... ...18
16 Sorangia massed along minor veinlets of lower pinnules of primary pinnae, becoming confluent, not aggregated in discrete sori, exindusiate... Osmundaceae
Sori discrete, with a hood-shaped 2-lipped indusium, or exindusiate with a basal ring of scales... ...17
17 Stipe bases scaly, lacking hairs; sori between midrib and margin, with a hood-shaped indusium or exindusiate with a basal ring of scales... Cyatheaceae
Stipe bases hairy, lacking scales; sori marginal, with a 2-lipped indusium... Dicksoniaceae
18 Fronds appearing dichotomously branched, or rarely in opposite pairs (Diplopterygium), usually with dormant buds in the axils... Gleicheniaceae
Fronds simple or variously divided, not appearing dichotomously branched, without dormant buds in the axils... ...19
19 Ultimate segments small and rounded with strongly reflexed margins forming pouch-like cavities... ...20
Ultimate segments variable, lacking strongly reflexed margins that for a pouch-like cavity... ...21
20 Lamina filiforme or pinnate, rhizome thick, densely clothed in reddish hairs... Platyzomataceae
Lamina or two pinnate branches at the stipe apex; rhizome slender and wiry with scattered appresssed scales... Gleicheniaceae
(Gleichenia abscida)
21 Sporangia in discrete, oblong or irregular patches, restricted to the basal half of minor costules; fronds filmy... Osmundaceae
Sporangia not as above... ...22
22 Sori covered by an indusium or by a reflexed pinna/pinnule margin... ...23
Sori lacking an indusium or other form of covering... ...47
23 Most or all sori borne on the underide of the pinnae away from the margins... ...24
Sori confined to marginal or submarginal areas of the ultimate lamina segments; if submarginal, usually covered by a reflexed pinna/pinnule margin... ...32
24 Sori rounded or elliptic... ...25
Sori elongate... ...29
25 Lamina simple, 1-pinnate or 1-pinnatifid... ...26
Lamina 2 - 4-pinnate or -pinatifid... ...28
26 Sori on anastomosing veins parallel and usually adjacent to the midrib; indusium semicircular... Blechnaceae
Sori on free veinlets, on free included veinlets or on vein tips, usually not adjacent to midrib; indusium orbicular to reniform... ...27
27 Pinnae articulated to the rachis, or stipe articulated to a phyllopodium; rhizome scales peltately attached; hydathodes prominent on upper surface of lamina at vein endings; basal veins from adjacent costules not uniting to form a translucent sinus membrane between two pinna lobes... Davalliaceae
Pinnae not articulated tothe rachis; stipe not articulated to a leaf-like outgrowth of the rhizome; rhizome scales attached along their basal margins; hydathodes absent; basal veins from adjacent costules often uniting and terminating in a translucent sinus membrane between 2 pinna lobes... Thelypteridaceae
28 Basal pinnae often enlarged on their basal side; indusium usually glabrous or with long silky hairs; rhizome scales +/- glabrous Dryopteridaceae
Basal pinnae not enlarged on their basal side; indusium with short capitate hairs; rhizomes scales hariy... Thelypteridaceae
29 Sori in long grooves close to the midrib or following anastomosing veins; groove margins extending into flaps; lamina simple; rhizome with clathrate scales... Vittariaceae
Sori not in grooves, covered by an indusium; lamina usually 1-4 pinnate; rhizome scales ussually not clathrate (except Aspleniaceae)... ...30
30 Sori parallel to midrib of ultimate sedments... Blechnaceae
Sori oblique to midrib of untimate segments... ...31
31 Rhizome scales clathrate... Aspleniaceae
Rhizome scales not clathrate... Athyriaceae
32 Indusium bivalved or cup-shaped... ...33
Indusium +/- rouned to elongate, flap like, or a reflexed pinna/pinnule margin... ...36
33 Sori borne on short or elongate receptacles terminating the veins or projecting from the lamina margins; lamina filmy 1-cell thick (rarely 2 or 3 cells) and translucent or lamina reduced to minute hairs (Sphaerocionium) or a barely perceptible wing along the axes of the frond (Crepidomanes p.p., Cephalomanes)... Hymenophyllaceae
Sori not borne on receptacles; lamina not as above... ...34
34 Rhizome and stipe base scaly, lacking hairs... Davalliaceae
Rhizome and stipe base hairy. lacking scales... ...35
35 Indusium of two distinct lips; inner lip membranous, outer lip a reflexed pinnule lobe... Culcitaceae
Indusium cup-like... Dennstaedtiaceae
36 Sori rounded to elliptic... ...37
Sori elongate or confluent along pinna margin... ...42
37 Indusium false (a reflexed pinna margin) or a flap opening towards the centre or base of pinna... ...38
Indusium reniform, semicircular, half cup-shaped or a broadly attached flap opening towards the pinna margin... ...40
38 Rhizome and stipe base hairy, lacking scales... Dennstaedtiaceae
(Hypolepis p.p.)
Rhizome and stipe base scaly, lacking hairs... ...39
39 Each ultimate segment with a single vein; fronds to c. 6 cm tall; epiphytic ferns... Grammitidaceae
Each umtimate segment witn many veins; most fronds at least 10 cm tall; terrestrial ferns... Adiantaceae
40 Rachis deeply grooved; lower margin of pinna and pinnules decurrent on edge of rachis groove; midrib rarely present Lindsaeaceae
Rachis not deeply grooved; lower margins of pinnae and pinnules not decurrent; midrib usually present... ...41
41 Rhizome and stipe base hairy; lacking scales... Denstaedtiaceae
Rhizome and stipe base desnely scaly, lacking hairs... 'Dennstaedtiaceae'
42 Lamina simple, entire; sori in long grooves with groove margins extending inwards as indusium-like flaps; rhizome scales clathrate; usually epiphytic ferns... ...Vittariaceae
Lamina 1 - 4-pinnate or pinnate-pinnatifid; sori not in grooves; rhizome scales not clathrate; usually terestrial ferns... ...43
43 Sori covered by a reflexed pinnule margin, sometimes also by a membraneous true indusium (best seen in immature fronds)... ...44
Sori covered only by a true indusium attached at the base and opening towards the margin... ...46
44 Frond to 2 ( - 3) m tall; rhizome long-creeping, hairy or scaly; stipe and rahcises predominantly yellow-brown Dennstaedtiaceae
(Pteridium, Histiopteris)
Frond to 50 ( - 70) cm tall with a creeping to erect scaly rhizome and dark brown to black rachises; or frond to 2 m tall, but with a short, erect rhizome and predominantly pale stipe and rachises... ...45
45 Stipe and rachises dark brown to black, usually glossy; fronds usually more than 70 cm tall... Adiantaceae
Stipe and rachises pale green, stramineus, pale brown or mid brown, rarely glossy; fronds usually more than 70 cm tall... Pteridaceae
46 Lowere margins of pinnae and pinnules decurrent on edge of rachis groove; midrib rarely present... Lindsaeaceae
Lower margins of pinnae not decurrent on edge of rachis groove; midrib usually present... Davalliaceae
Nephrolepis acutifolia)
47 Sori discrete or confluent but not covering all of the underside of the fertile pinnae/pinnules... ...48
Sori sporangia covering the whole of the underside of the fertile pinnae/pinnules ... ...60
48 Sori rounded or elliptic, remaining discrete... ...49
Sori elongate, or if rounded, submarginal and confluent... ...55
49 Lamina of two large, flabellate and deeply incised halves; rhizome with coarse dark bristles... Dipteridaceae
Lamina simple to many-times-pinnate, not of two large, flabellate and deeply incised halves; rhizome usuall with scales or hairs... ...50
50 Lamina 2 - 5-pinnate; terrestrial ferns... ...51
Lamina simple, 1-pinnatifid, 1-pinnate, 1-pinnate-pinnatifid or dichotomously branched; mostly epiphytic ferns... ...52
51 Rhizome scaly... Dryopteridaceae
(Lastreopsis p.p.;
Dryopteris hasseltii)
Rhizome hairy, without scales... Dennstaedtiaceae
(Hypolepis p.p.)
52 Sori forming 2 irregular rows between each pair of primary veins... Dryopteridaceae
Sori not forming two irregular rows between each pair of primary veins... ...53
53 Rhizome scales peltate and/or clathrate; stipes articulated to the rhizome or to a short, erect leaf-like outgrowth of the rhizome... Polypodiaceae
Rhizome scales neither peltate nor clathrate, usually attached along their basal margins; stipes not articulated to the rhizome nor to a short, erect, leaf-like outgrowth of the rhizome... ...54
54 Lamina simple, 1-pinnatifid, 1-pinnate, or dichotomomously branched; veins free, simple or forked... Grammitidaceae
Lamina 1-pinnate-pinnatifid; veins nearest costa usually anastomosing with an excurrent vein... Thelypteridaceae
55 Sporangia borne on narrow, apical portion of lamina... Polypodiaceae
Sproangia borne in laminal or marginal sori... ...56
56 Mature fronds simple or deeply pinnatifid, not pinnate; mainly epiphytic ferns... ...57
Mature fronds 1 - 3-pinnate; terrestrial ferns... ...58
57 Frond 1 - 3 cm tall; lamina simple; sori sunken in submarginal grooves parallel to the midrib... Grammitidaceae
Frond 30 - 80 cm tall; lamina deeply pinnatifid; sori not sunken, oblique to midrib... Polypodiaceae
58 Rhizome climbing or scrambling; fertile frond much narrower than sterile frond with linear segments 15-20 cm long and 2 - 3 mm wide... Blechnaeceae
Rhizome creeping or erect; fronds not strongly dimorphic... ...59
59 Rhizome with clathrate scales; lamina densely covered in hairs; sori laminal, growing on free veins... Aspleniaceae
Rhizome with dark bristles or basally attached non-clathrate scales; lamina glabrous or variously hairy; sori marginal, or if laminal, the pinnae glabrous and the sori either growing on free or anastomosing veins, or occupying a continuous band bewteen the midrib and margin... Adiantaceae
60 Sporangia massed along minor veinlets of lower pinnules of primary pinnae, becoming confluent; stipes with persistent basal stipular expansions... Osmundaceae
Sporangia not massed along minor veinlets of lower pinjules of primary pinnae; stipes lacking persistent basal stipular expansions... ...61
61 Rhizome with thick fleshy prop roots; fronds 1 - 4 m tall... Pteridaceae
Rhizome without prop roots; most or all fronds less than 1 m tall... ...62
62 Rhizome mostly creeping or climbing, dorsiventral; stipes articulated to the rhizome or +/- decurrent on it... Lomariopsidaceae
Rhizomes mostly erect, often forming a short trunk; stipes not articulated to the rhizome... Blechnaceae
Blechnum p.p.)

Updated November 1999 by Jim Croft ( )