Microlaena

For those of us who are interested in New Zealand botany, it is important to have an appreciation of all the ‘players’ within ecologies; whether they are the stars that automatically command attention, or character actors. I have, on several occasions before, expressed my belief that the supporting cast of less conspicuous species provide visual depth and resonance to nature’s planting schemes. To me, this is one of the key characteristics that imbues naturalistic planting compositions with a magical quality that is often missing in an approach that is focussed on assembling a garden of ‘star’ plants.

This genus of grasses may be utilised within gardens to convey a sense of quietude and charm, as they do within nature. In addition to this, there is for me an extra layer of interest to Microlaena – with regard to one species in particular. Microlaena stipoides is a remarkable plant which belies many of our perceptions of native species, by enduring (and often thriving) within many manmade landscapes and ecologies. It is, therefore, one constituent of a type of ecology that I find both fascinating and instructive; that of ‘hybrid’ landscapes – places that fit between natural and manmade, yet become something new (and of themselves) in the process of their formation.

Microlaena is a small genus of around five species¹ that occurs throughout much of the Pacific, of which four are native to New Zealand (two, M. carsei and M. polynoda being confined to our shores).

Considering the popularity of bamboos, one might assume that a plant called bamboo grass should have received the attentions of gardeners before now. Such an assumption is reinforced by the assertion of several authors (from John Buchanan in 1880 to Lawrie Metcalf in 1998) that it is a plant worthy of a place in gardens. However, Microlaena polynoda is almost completely unknown within cultivation.

Part of the reason is that this scrambling grass does not fit the normal paradigm of what constitutes a garden plant. Its tumbling form is amorphous, in contrast to the contained, tussocky form of the kinds of grasses (and sedges) that have predominantly found favour with horticulturists. It can become a little untidy if left untrimmed for a long time, but if given a minimal amount of care it fulfils a valuable role within plantings (in fact, the same can be said of most grasses and sedges – even the most popular garden varieties require maintenance).

Its form has been compared with a very popular ornamental species, gossamer grass (Anemanthele lessoniana); a comparison which is strengthened by the yellowish and orange tones sometimes present in older leaves.

The Dutch landscape designer, Piet Oudolf, champions the merits of plants that act as screens through which other plants may be viewed, thereby adding depth to plantings. Growing to 1m high, M. polynoda can add this attribute to plantings (especially if contrasted with a background of more defined forms, such as the strong foliage of many fern species), and can also play a connecting role in plantings, due to the lightweight manner with which it grows in association with other plants.

One of the chief incentives for using Microlaena polynoda is that its system is well suited to growing in many warmer parts of New Zealand. Many of the most commonly-planted grasses and sedges are species from areas in which they are continually knocked back by cold, wind or other factors. However, when grown within stable, mild conditions, such species either complete their life cycles far quicker than they would in nature, or throw out excessive amounts of growth.

M. polynoda, on the other hand, has a pseudo-shrubby growth habit, which is better adapted to northern parts of the country. Bamboo grass grows naturally in open forest, scrub and steep ground, and is often found near the sea (its most common natural station in the Auckland region).