The Beautiful South
Island, that is. Of New Zealand, where grows one
of the most attractive of all the near-hardy palms, the Nikau. Grab
your shaving brush and meet Peter in its most southerly habitat
there.
Peter Richardson, c/o Advanced Technologies Ltd., Science Park,
Cambridge
Chamaerops No.22, Spring Edition 1996
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Photo: the author, with Dicksonia for scale
In view of the viciously cold winter we have just
had, I thought this year I would go spore and seed collecting to
the southeast corner of New Zealand to maximise the chances of bringing
back material that was actually going to be hardy in my garden in
the UK. Two targets I had for this trip were to visit the southernmost
Nikau Palm colony on the South Island which is on Banks Peninsula
about 84km from Christchurch, and to collect treefern spores from
the southern end of the Island.
The Nikaus are in a reserve called Palm Gully reached
by a footpath several kilometres long from Onuku, a hamlet south
of Akaroa, a picturesque French colonial town. It is administered
by the Department of Conservation who have "closed" it
for the present because it is considered dangerous, although there
is no physical closure of the reserve. It is an extremely precipitous
ravine facing out over a cliff to the sea on the east side of Akaroa
harbour entrance facing south (i.e. away from the sun, equivalent
to 'north-facing' in the Northern Hemisphere), and reminiscent of
Cheddar Gorge in Somerset UK (though the rocks are volcanic, not
limestone) .
The bottom of the ravine is densely wooded, mainly
with Fuschia excorticata and Melicytus ramiflorus, and of course
the Nikau palms, some of which also cling to the steep sides of
the valley above the wood. These are the southern type, and their
fronds have very sturdy rachises and spread out at about 45 degrees.
Under the shade of the trees, the young plants are deep green and
lush, leaflets broad and arching outwards. With the variety of Aspleniums
and Blechnums also present, and a stream splashing down over large
rocks it has a delightful, subtropical look.
In fact I found it a puzzling place. The sun barely
rose above the cliffs at the back of the ravine when I was there
at the autumn equinox, so throughout the winter the gully must be
sunless, and as it faces out to sea it is open to winds coming up
from the Southern Ocean and Antarctica. It seems odd that this palm
should choose such a cold, sunless microhabitat at the southern
extreme of its natural distribution. There are hundreds of Nikaus
of all ages in the valley, but when searching adjacent valleys for
others I only found two scraggy old specimens in bushy grassland
grazed by sheep. I suspect that the reason for their abundance in
Palm Gully is simply that its precipitousness has protected it from
agricultural activity. All the surrounding valleys are part of a
sheep farm.
The palms do not show signs of bad frost damage. They
grow to the same height and stature as elsewhere and are flowering
profusely and fruiting without regard to the seasons as they do
further north. The ground gets a steady rain of ripe drupes, picked
at by the birds, and, in the deep shade of the broadleafed trees,
there are hundreds of small grassy seedlings. Overall, this palm
colony does not present the appearance of a plant at its climatic
limit.
Later when driving on southwards I was to find that
Phoenix canariensis is grown 500 km further south in Dunedin. I
saw two specimens in suburban gardens there, one adolescent and
one mature and flowering and fruiting. This also suggests that Rhopalostylis
could be capable of growing further south than Banks peninsula;
however the Canterbury Plains which extend north and south of the
peninsula have a long history of human disturbance, having been
almost fully cleared of forest by the Maoris, even before white
settlers arrived.
I also spent three days looking round the southeast
coast of the South Island, an area known as 'the Catlins', at around
46 degrees south. This part of the island is much drier than the
west coast, and not as mild in the winter. Naturally occurring Cordylines
are absent from this area but two hardy treeferns are found widely,
Cyathea smithii and Dicksonia squarrosa. Both are shaderequiring
species and are common under mixed forest at low altitudes. Even
these are absent from the coldest forests, which consist solely
of Nothofagus at higher elevations inland.
I walked up a track known as the 'Back Stream Road'
into these mountains, within Catlins Forest Park, from near Tahakopa.
C.smithii was the treefern that I found extending up the furthest,
with a few sporadic plants even in the pure beech forest above 500m.
These isolated specimens were comparatively short and entirely lacked
fertile fronds, at least this year, and I could only collect spores
from lusher groups further down.
Treeferns, when they finally get around to producing
spores, bear them in huge numbers and it is only necessary to take
two or three side pinnules of one leaf to end up with a decent sized
spore sample. Mine are now germinating.
I found fertile fronds of Dicksonia squarrosa even
scarcer; the only ones I found were on plants that had been left
when a block of bush just south of Papatowai had been cleared for
sheep pasture, leaving them out in the full sun - and their sporangia
were not ready to release their spores. There are patches of amazing
fern forest in the old stabilised sand dunes immediately behind
Tautuku Beach, where D. squarrosa has gained supremacy over all
other vegetation by suckering. Sheltered from the blasts of sandy,
salty wind off the Southern Ocean only by a ridge of marram-covered
sand, the trunks of the mature plants are three to five metres high.
The ground is lost beneath criss-crossed fallen dead fern trunks,
and new suckers continually rise through them to greedily occupy
any free space. Woody plants are relegated to the role of epiphytes,
perching on the ferns' trunks along with filmy ferns and a fragrant
orchid, Earina autumnalis; sublime exoticism at a latitude equivalent
to that of La Rochelle - certainly worth travelling to the far side
of the planet to see.
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