A Northumberland Alpine Gardener's Diary
This entry: 07 February 2013 by John Richards
New Zealand cushions. Entry 235.
New Zealand cushions
As the winter continues to grind on here, there is still relatively little to report on in the garden. This gives me an excuse to provide a third airing of some of the pictures I took in New Zealand in January 2003. On this occasion I intend to concentrate on some of the many remarkable cushion species which have mostly adapted themselves to a high alpine habitat on the windswept summits of many of the higher 'whalebacks'.
As one views our paltry efforts to attempt to grow New Zealand cushion alpines in the UK, it is easy to think that these are largely composed of the so-called 'Vegetable Sheep' in the genera Haastia and Raoulia (issue 233). In fact, nothing could be further from the truth. The richest of the high cushion alpine habitats are the great whalebacks of Otago, the Old Man, Pisa Range, Remarkables and others. Here an all-year round rainfall (but less than that in the west) is ameliorated by a typical, pulverising wind. Sites tend to be level, soils spongy, and permafrost features such as polygons and stone stripes are common. Here is a splendid example of stone stripes on the Pisa Range.
These very exposed damp, surface-dry, drained sites favour the development of cushions, and one of the signature features of the New Zealand alpine habitat is how many plant families have developed this adaptation in parallel. So NZ cushions belong not just to the Asteraceae (sheep and scabweeds), but the Boraginaceae (forgetmenots), Scrophulariaceae (Hebe relatives), Kellerias (Daphne relatives, Thymelaceae) and Caryophyllaceae (Scleranthus). Other cushions are placed in a clutch of southern hemisphere families little known 'up here' such as the Hectorellaceae, Stylidiaceae and Donatiaceae.
Bearing in mind the predeliction for tight alpine cushions favoured by many of our best known Exhibitors, it is remarkable how few of these cushions have succeeded in our gardens (compared for instance with the supposedly very difficult Dionysias, or Androsaces, Porophylla Saxifrages and their ilk). Also, it may be true that many of these NZ cusions are less easy to please in our gardens than formerly. Thirty years ago, nice flowery cushions of Chionohebe pulvinaris appeared regularly on the Show Bench (usually known then as Pygmaea pulvinaris). How often do you see them now? Here is C. pulvinaris growing on Mt Hutt in western Canterbury. (Chionohebe means 'snow hebe' by the way; very appropriate!).
Chionohebe pulvinaris is the most widespread 'snow hebe', and coming from relatively dry eastern ranges may prove to be the easiest in cultivation. Most of the other species are more local specialists. C. myosotoides for instance occurs only on the Pisa and Rock and Pillar Ranges of central Otago.
The relatively green C. thomsonii is another central Otago specialist, although it does range south into Southland. Here it is growing on the Old Man. It may occupy slightly drier microsites than C. pulvinaris.
Chionohebe ciliolata is another specialist, occurring only on the wettest mountains of the far south and west. Here it is on Mt Burns in Southland, a mountain that we reached by helicopter, a great thrill!
Now, I would submit to you, m'lud, that these four are quite the equal of any of our favourite European aretian androsaces. So why aren't we growing them? Is it because we won't, or we can't? Any bored Dionysia grower, here is a real challenge!
By the way. not all chionohebes are tight cushions. Here is C. densifolia, which rather belies its name. Also, it can, confusingly, have rather large lilac flowers, and further confounds the issue by unexpectedly turning up in Australia too! Here it is growing on the Pisa Range in Otago with the Epacrid, Pentachondra pumila. Incidentally, I read recently that the DNA suggests that the Epacridaceae should be included within the Ericaceae. Very small heaths!
Lets move on to the Myosotis. Forgetmenots have shown secondary adaptive radiation in New Zealand. None of them are blue, sadly, but then not all our British species are either, and in New Zealand there are some wonderful golds and browns. Here is M. macrantha growing near Mt Cook for instance.
However, like most Kiwi alpines, the majority, and all the cushions, have white flowers. The most widespread is M. pulvinaris, which is still sometimes grown here (in fact I have a small piece myself at present). Recent sendings have sometimes proved to be the related M. glabrescens, and the latter may be easier to grow. Here is the real thing on the Remarkables, above Queenstown.
Myosotis elderi is much more local, being confined to the drier mountains of Marlborough, as here on Mount St Patrick. It is a small plant, but not as tiny as M. pygmaea with which it often grows. The second photo shows the latter growing in cushions of Phyllachne colensoi.
Mention of phyllachne takes us friom our systematic comfort zone, and into the family of triggerplants, the Stylidiaceae, a totally southern family in its distribution. As mentioned above, the widespread species is P. colensoi, growing here on Mt St Patrick again.
There are also two southern specialities. Phyllachne rubra is a speciality of the Otago mountains, where it often grows with P. colensoi, as here, but has paler, blunter leaves
Phyllachne clavigera is only reported from the Pisa range, and is a slightly dubious taxon.
Hectorella caespitosa is member of another southern family (with a relative in Chile). It is also remarkable for being dioecious (male and female flowers on different plants). This photo is taken on the Old Man of Otago.
I love the next photo in which a nearly-cushion Gaultheria, no less, G. parvula, is growing embedded in cushions of phyllachne, also on the Old Man.
We finish with the daphne-relative Kelleria, perhaps more familiar as Drapetes, and Pimelea. First Kelleria croizatii, growing on the Remarkables.
A laxer species is K. dieffenbachii, which has been cultivated in the UK from time to time. Here it is growing above the haastias on Blackbirch.
On the same mountain grew its relative, Pimelea serico-villosa.
Finally, how could I forget the most wonderful, perhaps, of all the Kiwi cushions, which I first grew to love in the coloured plate in Bill Philipson's early book on the flowers of the southern Alps? Well, perhaps because Donatia novae-zelandiae is not really an alpine at all, but an unlikely bog-denizen from moderate altitudes. But I love it!