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NZ Plants

Trichomanes elongatum - bristle filmy fern

Filmy fern family: Hymenophyllaceae

Trichomanes elongatum is terrestrial filmy fern with a short erect stem bearing dark olive- green, hairless fronds with deeply toothed margins. Sporangia on the lower frond surface are attached to a central stalk (receptacle) which elongates at its base. Continued elongation of the receptacle carries sporangia to the mouth of the tubular indusium where they release their spores and are shed. The fully elongated receptacles of older fronds appear as conspicuous brown bristles extending from the lower leaflet surface. Formerly known as Abrodictyum elongatum.

A species found throughout New Zealand favouring dark, damp places.


Vegetative characteristics

Fertile frond and sporangia

Plant form: short erect stem with fronds up to 20 cm

Frond appearance: similar to sterile frond

Frond stalk, midrib: stalk hairless, not winged; midrib with narrow wing toward the tip.

Sporangium locationin notches of leaflets

Frond shape: triangular

Sporangium position: leaflet margin

Frond blade: 3 pinnate (divided 3x into leaflets of pinnae)

Sporangia distribution: in groups (sori)

Frond surface: rough, cartilaginous

Sorus shape: circular with sporangia arranged in many tiers around a central stalk (receptacle)

Leaflets: broad, deeply toothed

Sorus covering: indusium, tubular in shape