Every good keen kiwi garden should have one

Press, 31 January 1986, Page 14

Every good keen kiwi garden should have one

@ARDENER’S ; DIARY

Derrick Rooney

The New Zealand flora includes a number of plants which, by their rugged appearance and singular manner of growth, contribute to the unique character of the New Zealand landscape. Any Kiwi garden which is to give a suggestion of patriotism should Include, at least one of them.

They are the branching shrubs — bushes large or small with stiff, intertangled branches, often greyish, so that they colour the land with a smoky hue.

There are dozens of species, including unfamiliar ones in such familiar cultivated varieties as coprosma, olearia, pittosporum, and pseudopanax. A local one is Olearia virgata var. rugosa — a plant of mountain and subalpine shrublands east of the Main Divide in Canterbury and Otago. Often it grows in exposed, wet places, where its growth is stunted, so that it forms groups of low, densely branched bushes among tussocks which clearly put a New Zealand stamp on the scene. They are as Kiwi as Mallee gums and kangaroos are Australian.

In well-drained soil and some shelter, Olearia rugosa can grow 2m tall, but retains its rugged outline. It isn’t often grown in gardens but it could be effective in certain situations — e.g. grouped with red tussock (Chionochloa rubra) or astelias or mountain flax (Phormuium cookianum). Astelia nervosa, the silver mountain astelia, often associates with tussocks in the wild and would be a good companion for the olearia or other small-leaved native shrubs.

Wild clumps of Astelia nervosa almost always grow in wet places or near running water, but it grows well in drier conditions in the garden. The ordinary wild form is an excellent garden plant and selected forms are available which are even better. Some have quite reddish leaves and a Taranaki hybridist has crossed one of these with the huge Astelia chathamica to produce a stronggrowing hybrid with ruby red foliage. As yet this is not widely available, but I expect it will be in due course.

From a world total of

about 25 New Zealand has 13 unique species of astelia, so I guess we can claim to be the world centre of the genus. Most are plants of bush and swamps, but one which I have seen only in open, well-drained sites, growing, with tussocks or other low; vegetation, is Astelia petriei. I have collected specimens as low as 1500 ft and as high as 5000 ft. According to the “Flora of New Zealand, Vol. 1” this astelia grows in, permanently wet places, but I have seen it mostly on drier and more exposed sites than A. nervosa, though the two sometimes grow together. , They are superficially similar, but Astelia petriei may be identified by its generally smaller size and greener leaves and in the case of female plants, by the fruit, which are buried deeply among the

leaves, whereas those of A. nervosa stand clear. Both are easy to grow in the garden and associate well with tussocks or other ornamental grasses or small native shrubs. Astelia nervosa is often available from nurseries but A. petriei seems to be harder to find. As well as the red tussock, which is well known, there are several which could be used to good effect with branching shrubs or native brooms (or just about anything).

The common silver tussock (which used to be known as Poa caespitosa but is now an unnamed species) has a suckering habit which makes it unsuitable for garden use, but all the snow tussocks (Chionochloa macra, rigida, flavescens, and the unnamed Canterbury species which resembles flavescens) have a dense, tufted habit and very ornamental inflorescences.

None of these is easy to come by from nurseries but if you’re out in the hills grab a handful of seed. It isn’t difficult to raise. In a cool, shady place with plenty of mois-

ture you may be able to grow the lovely bush tussock (Chionochloa consplcua), which is, thanks to the height and elegance of the inflorescence, the most beautiful native grass of all. The flower sterris of the bush tussock may attain a height of almost three metres in favourable sites at bush margins on streamsides or in damp gorges, but I have seen it growing lustily on south-facing rocky outcrops. Suitable garden companions might be the leafy native brooms, Carmichaelia grandiflora or C. odorata, Hebe rakaiensis, or the divaricate coprosmas with which it often grows naturally. The genus Coprosma, according to the “Flora of New Zealand,” contains about 45 native species, but the Flora; published in 1961, is well out of date and there are . probably a dozen or more unnamed species. Which of these are suitable for garden use? Frankly. I can’t answer that question because I am not familiar with all of them. But next week I will write about some of the species I have seen growing.