Diplazium Swartz (Woodsiaceae) Earlier placement: Athyriaceae, Dryopteridaceae, Aspleniaceae, Polypodiaceae

Twin-sorus fern

Etymology From the Greek diplazios which means double, because indusia lie on both sides of the vein.
Description Rhizome: creeping to erect, scaly.
Frond: deciduous or evergreen, trophopod, monomorphic or weakly dimorphic.
Stipe: green, deeply grooved above, swollen or not at base, scaly or glabrous, vascular bundles: 2, lunate.
Blade: 1-2 pinnate (entire), oblong-lanceolate to deltate, herbaceous to papery.
costae U-grooved above, continuous from rachis to costae, segments entire, crenulate, or serrate, veins free or netted.
Sori: linear, basal sori paired back-to-back on the same vein, indusium: linear, persistent, sinus, sporangia: brownish.
Distinctive Characteristics Diplazium is very close to Athyrium, but the sori never hook over the veins, and are sometimes paired back-to-back. Additionally, the grooves in the rachis are U-shaped vs. V-shaped in Athyrium. Differs from Deparia in having the grooves continuous from costa to rachis.
Diplazium sibericum. A characteristic on the visible level distinguishing Diplazium from Athyrium is back-to-back sori.  Illustration from Scandinavian Ferns by Benjamin Ĝllgaard and Kirsten Tind, Rhodos, 1993.
Taxonomy The genus is large with 400 species, nearly all tropical. The few from temperate regions are not representative.
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