Zealand Alpine Plants
Challenge for Growers
from an article by Raymond Mole
From The New Zealand
Garden Journal (Journal of the Royal New Zealand Institute of Horticulture),
Vol. 1, No. 2, June 1996, pp. 9-11.
With increasing altitude,
New Zealand mountain ranges present us with an interesting cross
section of vegetation types. Lowland/montane forests of silver or
mountain beech give way abruptly to a wide range of shrubs, snow
tussocks, small or prostrate woody plants and low growing herbs.
Mark and Adams (1995) state that between the tree line and snow
line there is a greater range of alpine vegetation in New Zealand
than in most other parts of the world. About 93% of New Zealand's
alpine flora is endemic.
Alpine plants are strongly
adapted to the extreme climates found at high altitude. They often
grow in infertile soil or shattered rock, with great changes in
temperature from searing heat to extreme cold. They are often lashed
by gale force winds. The low-growing, creeping, mat forming and
cushion habit has obvious advantage in terms of wind resistance
and repetitive snow falls are unlikely to damage such plants. Another
feature of many alpine plants is a deep root system that provides
a strong anchorage. Water and available nutrients often lie far
below the surface in mountain habitats. Plants with deep root systems
are better able to exploit available food resources.
It may seem ironic to
talk about mountain plants suffering from water stress. Yet despite
high rainfall and water from snow melt many alpines are adapted
to minimise water loss. This is because most alpine soils are very
free draining, winds are frequent, and very high temperatures can
occur during the summer months. New Zealand alpines have adapted
to these conditions in many ways:
For example, distinctive
and unusual leaf characteristics are seen in many species of Aciphylla.
Commonly called speargrass or wild Spaniard, these herbaceous plants
with distinct whorls of narrow, spine tipped leaves and equally
spiny flower stems present a xerophytic countenance.
A few species of Carmichaelia
or native broom, inhabit alpine areas. Such species are leafless
and consist of short flattened branchless. I recall the difficulty
of transplanting a specimen of Carmichaelia monroi because
of its very long tap root.
Hairy leaves are another
way of limiting water loss on arid mountain sites such as screes.
The hairs catch water droplets from fogs and low cloud. New Zealand's
woolly vegetable sheep such as Raoulia eximia show this
type of adaptation. Not only do the exterior leaves inhibit water
loss, but within the cushion are the remains of old leaves which
rot down to form a peaty, water-holding sponge.
Growers attempting to
grow this species in lowland areas need to take measures to prevent
moisture clinging to the leaves, especially in humid conditions.
Failure to do this can cause softening of leaf tissue leading to
The adaptations above
are not exclusive to alpine plants but are found in other plants
growing in harsh environments subject to a lack of water.
alpines have a comparatively short growing season. They need to
grow, flower and produce seed between snow melt and fresh autumn/winter
snowfall. In Norway, Ranunculus nivalis has been
recorded in flower five days after snow melt and produced ripe fruit
seventeen days later.
The alpine flora in many
countries is highly coloured for instance Himalayan irises and primulas.
New Zealand alpines are far less colourful with flowers often white
or yellow. Never the less they are still attractive particularly
with their range of growth habits and foliage.
The 60 or so species
of Celmisia cover most New Zealand mountain ranges. They
are particularly eye catching when seen flowering en masse. As individuals,
white flowering daisies do not enthral me. It is their foliage in
which I find appeal. Many form rosettes of sword shaped leaves,
ranging in colour from grey/green to silvery grey to silver itself.
Perhaps none is more attractive in this regard than Celmisia
semi-cordata with its conspicuous rosettes up to 1 metre in
Some of the most distinctive
alpines are the vegetable sheep. My favourite is the hummocked form
of Haastia pulvinaris with its tightly rolled, compact,
hairy leaves on terminal shoots, truly at a distance looking like
Other noteworthy plants
of the alpine zone include North Island edelweiss, forget-me-nots,
buttercups, harebells (Wahlenbergia spp.), plus plentiful
displays of the graceful snow tussocks which tend to dominate the
low alpine areas.
How do these plants from
high mountains react to being grown in lowland gardens? Their performance
will be related to:
of the growing medium
At the Otari Native Botanic
Garden the site chosen for growing alpines had a southern aspect.
On the north side nearby trees 10-15 metres high formed the periphery
of the bush. Dry northerly winds are thus cooled and moistened as
they pass through. The trees also provide shade from the afternoon
Drainage material such
as small rocks and gravel was placed in a layer 15-20 cm thick at
a depth of 45 cm. A 5 cm layer of coarse sand overlays the lower
course. On top of this was the rooting medium containing a mixture
2 mm stone chips
river sand (agricultural pumice could be substituted)
Once the medium had been
added and shaped, rocks were placed.
I grew alpines in this
garden for over 20 years and many performed well, especially some
celmisias such as Celmisia spectabilis and C.
incana. The only trouble with C. incana was that in
spite of heavy flowering annually, the resultant seeds were not
viable. Some of the gems of the flora I found difficult to maintain.
Gentians proved almost impossible to keep going for more than two
years. Some woody plants lived but failed to flower, for instance
turn over in the alpine section was much greater than in other Otari
collections. The main exceptions were tussock grasses, Pentachondra
pumila, Ranunculus insignis, hebes, some celmisias including
those mentioned, and certain helichrysums, especially H. selago.
Raoulia hookeri was particularly easy and is an example of
a species with a wide distribution from coastal to alpine areas.
It seems that species with a wide altitudinal range are easier to
grow in a temperate garden.
Small plants grown in
containers in a shade house often performed better than their counterpart
growing in the alpine beds. The main cause of death was damping
Conditions that were
thought to promote ill health and short life spans included:
spells of humid warm weather
of soil pathogens
wet winters. Many alpines would usually be covered in a blanket
of snow for several months
My final assessment is
that cultivation of alpines in lowland parts of the North Island
will always be a challenge with some species always performing better
than others. It is a matter of trying a range of sites and soil
conditions to see which perform best for you.
Mark, A. F.;Adams, N.
M. 1995: New Zealand Alpine Plants. Godwit Publishing, Auckland.
The late Ray Mole, AHRIH,
was Curator of Otari Native Botanic Garden from 1963 until his retirement
in 1991. He died in 1995.