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NZ Plants

Blechnum nigrum - black hard fern

Hard fern family: Blechnaceae

  • Plant with fertile and sterile fronds

    L Jensen

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  • Sterile frond (left) and fertile frond (right)

    I MacDonald

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  • Frond stalk (stipe) with scales

    L Jensen

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  • Frond stipe with scales and hairs

    L Jensen

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  • Frond stipe, hair detail

    L Jensen

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  • Sterile frond upper surface, midrib (rachis) with leaflets

    I MacDonald

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  • Sterile frond upper surface, rachis with scales

    L Jensen

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  • Rachis hair detail

    L Jensen

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  • Sterile leaflet upper surface, marginal hairs

    L Jensen

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  • Marginal hair detail

    L Jensen

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  • Sterile frond lower surface, rachis and leaflelts

    L Jensen

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  • Sterile leaflet lower surface, hairs

    L Jensen

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  • Leaflet lower surface, detail of hairs

    L Jensen

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  • Fertile frond upper surface, rachis and leaflets

    L Jensen

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  • Sterile frond lower surface, rachis and leaflets with sori

    L Jensen

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  • Sorus with shrinking indisium covering exposing sporangia beneath

    L Jensen

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Blechnum nigrum is a small fern with short erect rhizomes bearing erect fertile fronds and prostrate sterile fronds with large terminal and basal leaflets.
An endemic fern found in dark lowland to montane forest on the North Island and on the west coast of the South Island.
 

Vegetative characteristics

Fertile frond and sporangia

Plant form: an erect stem bearing stiff, harsh fronds up to 30 cm long

Frond appearance: narrower and equal or longer in length than sterile fronds

Frond stalk, midrib: scales present on frond stalk (stipe); fine hairs present throughout

Sporangium location: on lower frond surface

Frond shape: narrowly elliptic to linear

Sporangium position: leaflet margin

Frond blade: pinnate (divided 1 x into leaflets or pinnae)

Sporangium distribution: in groups (sori)

Frond surface: leathery, fine hairs

Sorus shape: linear, often running together

Leaflets: oblong, round ended, irregular margins, attached along the base (adnate)

Sorus covering: linear covering (indusium) opening toward midrib

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