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NZ Plants

Hymenophyllum rarum

Filmy fern family: Hymenophyllaceae

Hymenophyllum rarum is small terrestrial or epiphytic filmy fern with long-creeping stems (rhizomes) forming extensive, interwoven patches of very thin, pale grey-green hairless fronds with smooth margins. Sori are sunk in the ultimate segments of the uppermost leaflets.
A species found in lowland and montane forest throughout New Zealand.

Vegetative characteristics

Fertile frond and sporangia

Plant form: creeping rhizome with fronds up to 15 cm

Frond appearance: similar to sterile frond

Frond stalk, midrib: stalk (stipe) wiry, hairless; midrib (rachis) with narrow wing in upper part.

Sporangium location: on terminal ends of leaflets

Frond shape: elliptic to oval

Sporangium position: leaflet margin

Frond blade: 1-2-pinnate (divided 1-2 times into leaflets or pinnae)

Sporangia distribution: in groups (sori)

Frond surface: filmy, translucent

Sorus shape: rounded

Leaflets: oblong, smooth margin

Sorus covering: indusium flaps smooth-edged