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NZ Plants

Cyathea dealbata - ponga, silver fern

Family: Cyatheaceae

  • Plants

    L Jensen

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  • Upper region of trunk, covering of broken frond stems (stipes)

    L Jensen

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  • Base of trunk, localised formation of a sheath of roots increases the girth

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  • Base of trunk, growth of roots occurrs in annual cycles

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  • Crown of plant with new fronds

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  • Young frond with scales

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  • Young leaflets with scales

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  • Scale detail

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  • Mature frond

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  • Frond upper surface, midrib (rachis) with leaflets

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  • Frond upper surface, midrib with leaflets

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  • Frond upper surface, midrib with hairs

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  • Mature frond lower surface, leaflets with full developed wax coating

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  • Young frond lower surface, early formation of surface wax

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  • Young frond, wax formation by epidermal cells

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  • Mature frond, lower surface, rachis with hairs

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  • Rachis with hairs and large scale

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  • Fertile leaflets lower surface, opening sori

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  • Sori with cup-shaped indusium coverings

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Cyathea dealbata is a tall tree fern characterised by silvery-green frond stalks (stipes) and soft fronds held horizontally that are distinctly silvery on the underside. Shedding of old fronds occurs when the stipes break some distance above their point of attachment to the trunk leaving the surface covered with persistent stipe bases.
An endemic species found on the North Island south to Dunedin on the South Island.
 

 

Vegetative characteristics

Fertile frond and sporangia

Plant form: trunks up to 10 m bearing fronds up to 4 m in length

Frond appearance: similar to sterile frond

Frond stalk, midrib: scales lacking marginal spines

Sporangium location: on lower frond surface

Frond shape: elliptic

Sporangium position: away from leaflet margin

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

Sporangia distribution: in groups (sori)

Frond surface: hairs on underside

Sorus shape: circular

Leaflets: oblong, round- toothed, pointed at the tip; attached along leaflet base (adnate)

Sorus covering: cup-like covering (indusium)

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