Plant Profiles

When we think of daisies, we tend to imagine low-growing herbaceous flowers, similar to the kinds of daisies that emerge through meadows or are planted in flower gardens. However, the daisy family is a very large family of plants which also consists of trees and shrubs, of which New Zealand has many representatives. One genus of woody daisies, Olearia, is especially well represented in a wide range of habitats throughout New Zealand. Olearia is an almost entirely Australasian genus, with a few stragglers north into New Guinea; and all of New Zealand's species of Olearia are exclusively found within this country.

The characteristic flower form of daisies is evident in all New Zealand Olearia, whether in large showy displays of usually white flowers (such as in Olearia angulata), or in smaller, almost indiscernable arrangements of flowers (such as in the scented coastal tree daisy, Olearia solandri). The daisy 'flower' form that most people will be familiar with is actually a collection of many flowers composed together within a group (a group of flowers is referred to as an inflorescence in botany).

To introduce a botanical note to this description, the parts that make up the inflorescence are called florets (effectively meaning small flowers). Within a traditional white ox-eye daisy form (such as that also exhibited in our native alpine daisies from the genus, Celmisia), there are two types of floret. The outer white florets (which look like petals) are called ray florets. The inner yellow florets (which, viewed together, look like a button in the middle of the inflorescence) are called disc florets.

Olearia nummulariifolia

Certain colours are valuable for evoking particular feelings in gardens. The vibrant grass green hue of Olearia nummulariifolia is one such colour. It is an excellent species for brightening arid or dark environments, whilst its pseudo-formal growth form makes it a useful shrub for lending informal structure to plantings.

Due to the harshness of its subalpine habitat, O. nummulariifolia is remarkably resilient to drought, cold and exposure. Surprisingly for a cold-climate species, a hybrid form of this species (O. nummulariifolia x coriacea) also adapts well to cultivation in warm, humid northern areas of New Zealand. In nature, it can grow to 3m, although in exposed positions it usually achieves a height of 1.6m or less. Plants of this species that I have observed on the Volcanic Plateau assumed remarkable 'bonsai' forms in response to constant battering from the elements.

We use Olearia nummulariifolia for its structural characteristics, either as specimens within naturalistic plantings or as informal hedging.