Tree Ferns

Tree ferns are commonly called Ponga.

Calling all tree ferns ponga is incorrect as only some tree ferns are ponga, these are Cyathea dealbata (Silver fern) and Wheki ponga of the Dicksonia species.

Tree fern fronds (leaves) are tripinnate:

The stem has a leaf coming off each side of it (Pinnate) and that leaf has leaves coming off each side of its stem (bipnnate) and those leaves have leaves coming off each side of its stem tripinnate).

Northland Tree Ferns form two groups

The two tree fern genius are Cyathea and Dicksonia.
They are distinguished by the following.

The Cyathea tree ferns

There are 7 endemic species to New Zealand and about 650 world wide.

• Cyathea cunninghamii Gully tree fern, Slender tree fern, Ponga, Pünui.
• Cyathea dealbata Silver fern, Kaponga, kātote;
• Cyathea medullaris Black Tree Fern, Mamaku
• Cyathea smithii Common names : Soft Tree Fern, Katote, Smiths Tree Fern:

Not in Northland

• Cyathea Colensoi Mountian tree fern
• Two in the kermadecs islands only

Not endemic to NZ,

• Cyathea cooperi an Australian species

Cyathea usually have a single stem growing upwards, some species also develop a fibrous mass of roots at the base of the trunk.

For more information about the relevant individual species simply click on the links provided above

The Dicksonia tree ferns on the New Zealand main land are

Wheki – Dicksonia squarrosa

Grows to about 6m. The wheki produces a few fronds which grow vertically from the trunk and then bend down. The fronds are 1.5 – 3m in length . It has a slender black trunk often looking untidy with many dead fronds hanging off it . The wheki has spreading underground rhyzome which can sprout new trunks and form thick groves.

identifying the Wheki
is readily recognised by the black stipe bases on the trunk, the presence of aerial buds, the very harsh fronds, and the characteristically orange-brown dead fronds. There are red-brown, rigid, multicellular, uniformly distributed hairs on the abaxial surface of the costae. If the crown or upper part of the trunk is damaged, the aerial buds may grow out to form a multi-headed tree fern. The stoloniferous habit means that the species often grows in groves, with a mixture of young and old trunks.

Occurs under mánuka, tawa, pohutukawa, podocarp, beech and broadleaved forest, or in second growth forest, open scrub, on forest margins, and occasionally in dune hollows or open pasture. It often grows along creek banks, or on poorly drained or swampy soil. It frequently forms extensive groves; the dense shade, combined with the dead fronds that cover the ground, tends to discourage germination of any other species underneath the grove.

photo on nature walk

Lanata or tuakura – Dicksonia lanata –

There are two subs species Dicksonia lanata hispida which occurs from the kaipara harbour northwards,and the lanata subspieces lanata which occurs from the Coromandel south.

Dicksonia lanata hispida
This is a short trunked tree fern found most commonly as an understorey plant in kauri forest. It has a trunk 0.2- 2 m tall about 150mm in diameter. The fronds are 0.5 – 2m and rise upwards from the trunk.They have a long, pale brown stalk and dark green foliage. dead fronds are orange brown

The Dicksonia lanata hispida has rigid, red brown hairs among shorter, fine, pale brown hairs on the underside of the costae and pinna midribs

Refereances

“Sourced from Landcare Research”

Dicksonia fibrosa

wheki ponga, wheki kohoonga, golden tree fern, kuripaka

Stout tree fern up to 10 m tall. Trunk solitary, dense, made of red brown interwoven rootlets, Fronds forming dense crown, dying and leaving a tidy, persistent skirt beneath crown.

The fibrous trunk of Dicksonia fibrosa grows up to 60cm in diameter. and can be up to 10 m tall. The fibrous truck is much thicker and the fronds are much lighter than Dicksonia squarrosa. Most of the bulk of the stout trunks is made up of interwoven wiry roots. As the old fronds wither they simply hang down from the trunk like a skirt, this is important as these dead fronds protect the tree fern from drying out. The mature fronds are 2 metres long.

The Maoris use to hew off wide slabs of the fibrous matter and utilise them in the building of food stores. This material is durable and is a bar to rats, which do not seem able to gnaw through it.

The need for conservation

It is apparent that the fate of the ecosystem in the Tangihua Ranges depends on putting in place conservation strategies which will significantly reduce or stop the damage inflicted by introduced pests. Most of the above species, if this is done will regenerate or can be successfully reintroduced and established.

DOC does not have enough funding to conserve the Tangihua forest, it is up to the community and others to step up.

We have set up two conservation programs so far

• Tangihua Community Pest Control Area click here for more information
• Conservation on DOC land click here for more information
• Conservation education click here for more information
• Volunteers options click here for more information

References

it is very apparent that specific information has been shared online between many organisations. Attributing to the initial source is impossible. As much as possible we use our own photos but this will take time and for extinct birds that is not possible. We have used the following websites as sources for our information

• Te Ara The Encyclopaedia of New Zealand
• Wikipedia
• T.E.R:R.I.A.N Taranaki Education resource: research and information network
• Te Ara The Encyclopaedia of New Zealand