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Athyriaceae

Incl. Hypodematiaceae

Terrestrial ferns of small to moderate or large size, rhizome a radial caudex, mostly erect, dictyostelic, young parts densely covered with non-clathrate, non-peltate scales. Fronds long-stipitate, the stipes not articulate to the rhizome, 2 vascular bundles at the base uniting upwards into one of +/- U-shape, the lamina simple, or pinnate to decompound, thin to leathery, axes generally grooved, the margins of lamina not decurrent with then margins of the grooves, veins forked, free to the margin or anastomosing without free included veinlets, rarely ending in an intramarginal vein. Sporangia in sori elongate along the veins, protected by an elongate indusium attached along the veins, the indusium sometimes curved across the vein at the distal end of the sorus, sometimes thin and bursting to expose sporangia, rarely exindusiate, sometimes short, round or reniform, stalk slender, 3-seriate, annulus longitudinal, interrupted; spores monolete reniform, smooth to muricate or spinescent or rugose-reticulate, with perispore.

Distribution

A widespread family of c. 25 sometimes doubtfully distinct genera, containing c. 600 species. In Papuasia there are 8 genera with c. 60 species.

Literature

Copeland, E.B. 1949. Aspidiaceae of New Guinea. Philip. J. Sci. 78: 389 - 475.

Iwatsuki, K. 1964. On Hypodematium Kunze. Acta Phytotax. Geobot. 21: 43 - 54.

Kato, M. 1984. A taxonomic study of the Athyrioid fern genus Deparia with main reference to the Pacific species. J. Fac. Sci. Univ. Tokyo sect. 3, 13: 375 - 429.

Sarvela, J. 1978. A synopsis of the fern genus Gymnocarpium. Ann. Bot. Fennici. 15: 101 - 106.

Genera

1a.

Veins Free

2

1b.

Veins anastomosing; sori elongate along the veins

7

2a.

Sori indusiate; frond axis abruptly not bent at insertion of stipe on lamina

3

2b.

Sori exindusiate; frond abruptly deflexed through 90 degrees or more at insertion of stipe on lamina

Gymnocarpium (1)

3a.

Groove of rachis open to admit grooves of branch rachises and midribs of leaflets

4

3b.

Groove of rachis not open to admit grooves of branches (Lunathryium)

Deparia (1)

4a.

Lamina and indusia bearing numerous long white setae

Hypodematium (1)

4b.

Lamina and indusia not so-covered

5

5a.

At least some sori elongate along veins

6

5b.

Sori not elongate along veins

Cystopteris (1)

6a.

Double sori (on both sides of the vein) not connected across their distal ends

Diplazium (c. 50)

6b.

Double sori (at least some of them) connected across their distal ends, usually some reniform of J-shaped sori present

Athyrium (1 -2 )

7a.

Veins anastomosing regularly, several veins of adjacent groups uniting to form an excurrent vein; sori on nearly all veins on the lower surface of the fertile frond

Callipteris (3)

7b.

Veins anastomosing less regularly, usually only the basal veins of each group uniting, or anastomosing near the margin without excurrent veins; sori never so abundant.

8

8a.

Indusium rather firm, its edges reflexed at maturity

Diplazium (c. 50)

8b.

Indusium thin, sausage-shaped, breaking at maturity, its edges not reflected

Diplaziopsis (1)

Note

Some authors unite Callipteris with Diplazium and others unite Diplazium with Athyrium; in the latter two at least, there is significant cytological evidence for keeping the genera separate.

There has been some uncertainty over the placement of Gymnocarpium in the Athyriaceae, however it appears to be less anomalous her than the alternatives, Dryopteridaceae or Hypoderriaceae. On the basis of several correlated characters, the single Papuasian representative of this genus has been assigned its own genus, Currania, distinct from Gymnocarpium; Sarvela 1978) considers Currania to be a monotypic subgenus of a broader Gymnocarpium.

Hypodematium has also been included in the Hypoderriaceae by some authors and has even been allocated its own family, the Hypoderriaceae.

The Athyriaceae has in the past been combined with Aspleniaceae due to similarities of soral and indusial structure. Chromosomal and other morphological differences indicate that the two families should be maintained separately and this is more or less universally accepted today. It would be more correct to unite this family with the Dryopteridaceae and Tectarioid genera into a large and diverse family, the Athyriaceae.


Updated November 1999 by Jim Croft (jim.croft@environment.gov.au)