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NZ Plants

Tmesipteris tannensis - fork fern

Family: Psilotaceae

Tmesipteris tannensis is occasionally terrestrial but usually an epiphyte on tree fern trunks. It has a creeping stem (rhizome) that lacks roots, absorbing water instead with filamentous rhizoids. A pendulous and undivided aerial stem is formed that lacks true leaves, functioning instead with scale leaves. Scale leaves are spirally arranged, shiny green, narrow, tapering to a long spine-like tip and brittle. Pointed-ended sporangia are fused in pairs and lie on the upper surface at the base of forked fertile leaves.
Found throughout New Zealand. 


Vegetative characteristics

Fertile frond and sporangia

Plant form: pendulous unbranched stem, up 100  cm long

Leaf distribution, appearance: throughout the stem; forked, same size as sterile leaves

Leaf arrangement: spirally arranged

Sporangium location: upper surface of leaf

Leaf shape: narrowly ovate with blunt or truncate ends and a long, spine-like tip

Sporangium position: on base of leaf below fork

Leaf size: up to 30 mm long 

Sporangia distribution: in a fused pair (synangium)

Frond surface: glossy green, stiff, brittle

Sporangium shape: with pointed ends