Aquarium ferns dichotomous keys
Interactive dichotomous keys to determinate ferns species kept in aquariums
ferns dichotomous keys, aquarium fern dichotomous key, aquarium fern, crepidomanes, microsorum
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This keys refers to emerged plants in nature, inside the brackets is described the aquarium equivalent when possible


How to use them:

Trough this page, you will be able to determinate fern families, by clicking on the fern family name, you will be redirected to other keys which will allow you to determinate the plant genus, from there by clicking on the genus you will be able to determinate the species


Keys to the family:

1 Whole plants floating with the roots or root-like submerged leaves suspended in the water, sporangia in sporocarps (same aquariums). Go to 2
Plants growing in soil, mud or epiphytic (non-floating ferns unless untied, usually tied on rocks or wood or growing in the gravel). Go to 3

2 Small leaves up to 1.5 mm long, scale-like and overlapping.  The whole plant can be 0,8-6 cm long, the rhizome bears leaves in two alternate rows and has many thin roots, sporocarps in pairs  (same in aquariums).  Azollaceae


Credit: Duke University

2a Large leaves up to 1-3 cm long, The whole plant can be 5-20 cm long, the rhizome bears three leaves, two form an opposite pair over the water surface and the third which is located under the surface is finely divided and root-like, sporocarps in clusters (same in aquariums).  Salviniaceae

salvinia minima


3 Aquatic plants, with submerged rhizome, in the mud, some leaves might be floating. Leaves divided about equally into 4 radial lobes at the end of a long stalk, sporangia in one or more sporocarps near the base of the stipe or on the stipe.  (submerged plants have leaves with 1-4 lobes at the end of a long stalk, rhizome running on the gravel forming a carpet-like mat). Marsileaceae

3a Aquatic ferns, occasionally terrestrial, with grass-like linear narrow leaves, from a basal rosette, basal sporangia included in leaves tissue (same in aquariums). Isoetaceaeisoetes3b Not as above, sporangia borne on ordinary or specialized fronds. Go to 4

4 Succulent aquatic plants, fronds bi-tripinnatifid, marginal sori covered by reflexed leaf margin. Pteridaceae



4a Terrestrial ferns, epiphytic or litophitic (most ferns in aquariums are terrestrial). Go to 5

5 Exindusiate sori, superficial or borne in grooves, not covered by a reflexed leaf margin. Simple fronds pinnatifid or pinnate without hirsute hair on stipe or leaf margin. (Sori are visible in emerged plants but usually not in aquarium, pinnate or pinnatifid fronds, without hair on leaf marginPolypodiaceaeMicrosorum vietnam blake5a Sori with indusium or covered by a reflexed leaf margin. Go to 6

6 Marginal or submarginal sori, small fronds,  sporangia borne in a receptacle, tubular or bivalvate indusium on the tips or upper margins of segments. (Marginal or submarginal sori often present also in submerged form, tubular or bivalvate indusium in the tips or upper margin of the segment, small frondsHymenophyllaceae

Crepdidomanes sp. Lampung 01

6a Dorsal sori or most of the sori not born near the margin. Go to 7

7 Sori parallel to the oblique veinlets, clathrate scales in the basal stipe, the 2 vascular strands at the base of stipe united in the upper stipe forming a single x shaped strand, linear single indusium. AspleniaceaeHymenasplenium obscurum
7a Sori circular or elongate on the vein or at the vein ending, non-clathrate scales in the basal stipe, stipe base not articulate. Lamina pinnate, seldom bipinnate often with reticulate venation. Dryopteridaceae (Bolbitis)


Credit: aquaflora