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NZ Plants

Hymenophyllum dilatatum - muku

Filmy fern family: Hymenophyllaceae

Hymenophyllum dilatatum is an epiphytic filmy fern with long-creeping stems (rhizomes) bearing bright green hairless fronds with broad leaflets with smooth margins. Numerous sori with smooth flaps are present on each leaflet.
An endemic species found throughout New Zealand noted for its very large fronds.

Vegetative characteristics

Fertile frond and sporangia

Plant form: creeping rhizome with fronds up to 50 cm

Frond appearance: similar to sterile frond

Frond stalk, midrib: stalk stout, hairless, winged for part of its length; midrib with broad wing throughout.

Sporangium location: at tips of leaflets

Frond shape:  oval to lanceolate

Sporangium position: leaflet margin

Frond blade: 3-4-pinnate (divided 3-4 times into leaflets or pinnae)

Sporangia distribution: in groups (sori)

Frond surface: filmy, translucent

Sorus shape: dome shaped

Leaflets: broad, smooth margin

Sorus covering: indusium flaps smooth-edged