Fertile material attached to the frond's underside, but without an indusium. Gymnocarpium: Plants widely creeping, deciduous, fronds triangular and delicate.
Polypodium: Plants short-creeping, forming dense clumps, often on trees, deciduous or evergreen, fronds lance-shaped, pinnatifid to once-pinnate. Phegopteris: Plants widely creeping, deciduous, fronds bipinnate to tripinnate.
Fertile material on the frond's underside, indusia present.
Asplenium: Plants usually evergreen, hardy material often small, sori in a herringbone pattern. A few species are dimorphic. Athyrium: Plants usually deciduous and large, sori J-shaped or half-moon-shaped but occasionally linear.
Cyrtomium: Plants usually evergreen with sickle or holly-like foliage, indusium peltate (round and centrally attached like an umbrella) on sori randomly scattered on the frond's underside.
Cystopteris: Plants deciduous, sometimes with bulbils, fronds lance-
shaped, sori covered by a hooded indusium.
Dryopteris: Plants evergreen or deciduous, varied shapes, frequently scaly, indusium kidney-shaped.
Polystichum: Plants evergreen, scaly with spiny foliage with a pinnule thumb, indusium peltate, sori usually edge the margins of the fronds. Thelypteris: Plants deciduous, spreading, soft-textured, hairy but not scaly, indusium when present kidney-shaped or occasionally round, on veins. Woodsia: Plants deciduous, small, rock loving, indusium under the sori opening in starlike fashion.
Some Woodwardia: Plants tall and vigorous, evergreen, sori in sausagelike chains.
Fertile material with a false indusium of an inrolled pinna margin.
Adiantum: Fronds often fan-shaped, delicate, temperate species usually deciduous with wedge-shaped pinnae.
Cheilanthes: Plants hairy or scaly, upright growing in exposed sites, usually evergreen.
Pellaea: Plants not hairy, frequently with bluish foliage, growing in exposed sites, usually evergreen.
Once the genus of a plant is determined, details of the frond architecture and pinnae outlines (see the accompanying drawings) help to identify the species. Besides frond division look in the descriptions for notes on the patterns of the veins, which can be free or "netted" (joined), as well as details of scales, hairs, vascular bundles (those tubes that carry nourishment to the foliage) and other visual botanical clues. Knowing the native habitat, or country of origin, of the fern is immensely helpful as well, especially given an extensive library. For the pure pleasure of enjoying ferns for their ornamental addition to the garden composition, all of this may be superfluous. My advice? Enjoy.
Cystopteris montana by John E. Sowerby from The Ferns of Great Britain by John E. Sowerby and Charles Johnson, London, 1855.
Crozier (Fiddlehead) ^
Was this article helpful?