Relations of the coffee tree make distinctive ornamental fruiting shrubs

Press, 7 February 1986, Page 15

Relations of the coffee tree make distinctive ornamental fruiting shrubs

JARDENER’S ! DIARY

Derrick Rooney

The trouble with coprosmas as garden plants is that — excluding the hybrids which are grown for their foliage — the most conspicuous feature of the majority of species is their fruit and to get these you must ensure that you have a female plant. As happens quite a lot among New Zealand plants, coprosmas have male and female flowers on separate bushes. Unfortunately the horticultural trade in general has failed to recognise the potential of coprosmas as ornamental fruiting shrubs, and so to find a coprosma labelled as to sex in a nursery is the exception rather than the rule.

Even if you do secure a female plant your troubles are not over, because to get fruit you must ensure that there is a male plant somewhere in the vicinity. If this makes you feel that coprosmas are just too much hassle, stop worrying; even without fruits the coprosmas can, with their rugged branching

and distinctive outlines, contribute much to the garden scene. Coprosmas belong to the botanical family Rubiaceae and are thus distant relatives of the coffee tree — a relationship you can see if you compare a seed of, say, Coprosma lucida with a coffee “bean.” It is not exclusively a New Zealand genus because upwards of 50 species are scattered through the Pacific Islands, Australia, and Hawaii, but all 50-odd New Zealand species are unique to this country. Many of them have the dense, divaricating branching habit which I mentioned last week and which is a feature of a number of New Zealand plant genera. Hardy species which

grow naturally in Canterbury are amenable to cultivation include C. Propinqua, rugosa, ciliata, cheesemanii, acerosa, and taylori (the provisional name for a small-leaved species which- is at present undescribed). Coprosma taylori often has a splash of creamy yellow variegation on its tiny leaves. When it grows in bush it is a big, loosely branched shrub but on open, rocky sites it is so densely branched that collecting seed from it is difficult. Its small, round fruit are most often translucent pearly white, but some bushes have pale yellow fruit, and these are to be preferred in the garden. Coprosma propinqua and C. rugosa have blue fruit or whitish fruit speckled with blue; C. ciliata has bright red fruit. All these may reach a height of 2m or more. Where something smaller is needed try C. cheesemanii or C. acerosa. When well grown both of these are striking little bushes, the former because of its rugged out-

line and the latter on account of its wiry brown stems.

Coprosma cheesemanii, found at subalpine altitudes, is a flatfish bush with dense horizontal branching and showy red fruit.

Coprosma acerosa is a low, often prostrate and suckering, bush with a wide altitudinal range from coastal dunes to montane river terraces and outcrops (the smaller alpine forms were previously known as Coprosma brunnea).

The species is easily raised from seed and it is worth planting several seedlings in a clump to ensure that you have at least one female.

Coastal forms- of this coprosma are generally of looser growth and have paler fruit than the bright blue alpine forms. All like a site in full sun and once established will survive considerable drought. Tip cuttings of firm young shoots strike readily and are the best way to perpetuate good forms, the best of which are probably not yet in cul-

tivation. The common form in horticulture appears to be a male plant of coastal origin and though it has nice orangebrown stems it has a rather loose habit of growth. Rather similar to the coprosma in general appearance — though it belongs to the dogwood family — is Corokia cotoneaster, a rugged shrub which occurs naturally throughout the main islands and is a prominent Canterbury plant.

Corokia is one of the most wind-tolerant shrubs and once established will withstand prolonged drought — its natural habitat is in dry rocky areas. In spring it is covered with pretty, starry yellow flowers which are succeeded in late summer or autumn by small, hard fruit which may be yellow, orange, or red. I like the yellow ones best, and there are some good examples in the Lake Coleridge area. Bushes do not transplant readily but tip cuttings of firm young growth may be struck in a frame.