Hymenophyllaceae

Callistopteris apiifolia, photographed by Joel Nitta.

Belongs within: Leptosporangiatae.
Contains: Hymenophyllum, Trichomanes.

The Hymenophyllaceae include the filmy ferns, mostly small ferns that get their vernacular name from their thin translucent fronds, with blades generally only one cell thick. Generic subdivisions within this family have varied significantly between authors, but most recent studies agree on a basal division between broad Hymenophyllum and Trichomanes lineages. One of the largest species of Hymenophyllaceae, the kidney fern Cardiomanes reniforme, has been suggested to be the sister of all other Hymenophyllaceae, but Pryer et al. (2001) resolved it as the sister to the Hymenophyllum lineage.

Characters (from Smith et al. 2006): Terrestrial and epiphytic; rhizomes slender, creeping, wiry, or sometimes erect and stouter, protostelic; vernation circinate; blades usually one cell thick between veins; stomata lacking; cuticles lacking or highly reduced; scales usually lacking on blades, indument sometimes of hairs; sori marginal, indusia conical (campanulate), tubular, or clam-shaped (bivalvate), with receptacles (at least in trichomanoid genera) usually elongate, protruding from involucres; sporangia maturing graduately in basipetal fashion, each with an uninterrupted, oblique annulus; spores green, globose, trilete; gametophytes filamentous or ribbon-like, often reproducing by fragmentation or production of gemmae; x = 11, 12, 18, 28, 32, 33, 34, 36, and perhaps others.

<==Hymenophyllaceae [Hymenophylloideae]
    |  i. s.: Hymenoglossum cruentum PS01
    |         Rosenstockia rolandi-principis PS01
    |         Meringium DF97
    |           |--M. bivalve [=Trichomanes bivalve Forster 1786, H. bivalve (Forster) Swartz 1801] C49
    |           |--M. denticulatum [=Hymenophyllum denticulatum] I77
    |           |--M. holochilum [=Hymenophyllum holochilum] DF97
    |           |--M. meyenianum [=Hymenophyllum meyenianum] I77
    |           |--M. minimum [=Hymenophyllum minimum Rich. 1832] C49
    |           `--M. multifidum (see below for synonymy) C49
    |         Crepidopteris endlicheriana [=Trichomanes endlicherianum Presl 1849-1851] C49
    |         Hopetedia SS04
    |         Craspedophyllum armstrongii (see below for synonymy) C49
    |         Apteropteris malingii (see below for synonymy) C49
    |--+--Hymenophyllum PS01
    |  `--Cardiomanes [Cardiomanoideae] PS01
    |       `--C. reniforme [=Trichomanes reniforme Forster 1768] C49
    `--+--Callistopteris DF97
       |    |--C. apiifolia [=Trichomanes apiifolium] I77
       |    `--C. baueriana [incl. C. baldwinii, Macroglena toppingii] DF97
       `--Trichomanes PS01

Apteropteris malingii [=Trichomanes malingii Hooker 1862, Hymenophyllum malingii (Hooker) Mettenius 1864] C49

Craspedophyllum armstrongii [=Trichomanes armstrongii Baker 1868, Hymenophyllum armstrongii Baker 1873, Hymenophyllum cheesemanii var. armstrongii Cheeseman 1906] C49

Meringium multifidum [=Trichomanes multifidum Forster 1786, Hymenophyllum multifidum (Forster) Swartz 1801] C49

*Type species of generic name indicated

REFERENCES

[C49] Crookes, M. W. 1949. A revised and annotated list of New Zealand Filicinae. Transactions and Proceedings of the Royal Society of New Zealand 77 (2): 209-225.

[DF97] Dassler, C. L., & D. R. Farrar. 1997. Significance of form in fern gametophytes: clonal, gemmiferous gametophytes of Callistopteris baueriana (Hymenophyllaceae). International Journal of Plant Sciences 158 (5): 622-639.

[I77] Iwatsuki, K. 1977. Studies in the systematics of filmy ferns III. An observation on the involucres. Botanical Magazine, Tokyo 90: 259-267.

[PS01] Pryer, K. M., A. R. Smith, J. S. Hunt & J. Y. Dubuisson. 2001. rbcL data reveal two monophyletic groups of filmy ferns (Filicopsida: Hymenophyllaceae). American Journal of Botany 88 (6): 1118-1130.

[SS04] Schneider, H., E. Schuettpelz, K. M. Pryer, R. Cranfill, S. Magallón & R. Lupia. 2004. Ferns diversified in the shadow of angiosperms. Nature 428: 553-557.

Smith, A. R., K. M. Pryer, E. Schuettpelz, P. Korall, H. Schneider & P. G. Wolf. 2006. A classification for extant ferns. Taxon 55 (3): 705-731.