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NZ Plants

Hymenophyllum demissum - irirangi, drooping filmy fern

Filmy fern family: Hymenophyllaceae

Hymenophyllum demissum is a terrestrial or epiphytic filmy fern with long-creeping stems (rhizomes) bearing pale green hairless fronds with smooth margins, pointed and usually paired sori.
A very common endemic species found throughout New Zealand.

Vegetative characteristics

Fertile frond and sporangia

Plant form: creeping rhizome with fronds up to 25 cm

Frond appearance: Similar to sterile frond

Frond stalk, midrib: stalk stout, hairless, not winged or with a narrow wing; midrib with narrow wing.

Sporangium location: on terminal ends of leaflets

Frond shape: elliptic to oval

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: pointed

Leaflets: oblong, smooth margin

Sorus covering: indusium flaps smooth-edged or slightly toothed, triangular, often in pairs