Mazus

I’ve always been intrigued by the term ‘Vagrant’ as applied to plants. It is one of those words that is so bound to people that its use in describing certain plant species lends them a human character; as if they were a drifter in a short story. Mazus pumilio is one of these botanical ‘drifters’; having gained a tenuous foothold on Northland’s eastern coastline, yet never spreading further from the single population that was discovered at Whananaki in the 1990s. Like some other plants that turn up naturally in New Zealand, Mazus pumilio most likely arrived from Australia with the assistance of a bird, as opposed to the other main pathway for species that are new to our shores – the wind.

The genus is well established here, with several species and varieties (some with remarkably long-winded botanical names) distributed throughout the country. Whilst on the subject of names, the genus derives its title from the Greek word, ‘mazos‘ (meaning breast or teat¹), in reference to two nipple-like structures in the flower. Due to this, members of Mazus are sometimes known by the name of ‘teat’ (as in the case of Mazus novae-zeelandiae ssp. impolitus f. hirtus, pictured above, which Oratia Native Plant Nursery mischievously endowed with the name of ‘hairy teat’), although ‘musk’ is the more common title applied to Mazus.

Mazus pumilio is the species that is generally seen within gardens in New Zealand, where it withstands a wide range of conditions (including surprising amounts of shade and drought), whilst Mazus radicans (shown above, growing within beech forest understorey) is the other species that makes a regular appearance in literature or nursery catalogues. Within our work, we have specified M. pumilio in many projects over the years, on the basis of its tough constitution, lilac flowers and bright green foliage. However, for the last few years, we have focussed more on the critically endangered Mazus novaezeelandiae ssp. impolitus f. hirtus, which differs in possessing mostly white flowers and dark-tinted leaves.

In terms of basic geography, seeing this diminutive character in the wild is no easy task – at least from the perspective of an Auckland-based landscape designer. The sole remaining populations occur near Kaitaia and East Cape; destinations that required a fair amount of time and effort to reach on the occasions that I was fortunate to observe this extremely rare groundcover in the wild – although both areas are not short on other botanical treasures to make the journeys even more worthwhile.

Near Kaitaia, we were grateful to Kevin Matthews for showing us the population at Foleys Bush (an extremely significant swamp forest remnant), where the Mazus² grows in close proximity to a nationally threatened small tree in which we are especially interested (Pittosporum obcordatum) and a critically-endangered ground fern with tropical origins, Christella dentata.

Kevin made the observation that the increasing prevalence of nikau palms, and more precisely the fronds that nikau drop on the understorey, represents an unusual (that is, native) threat to Mazus – due to this species’ requirement for open ground (either within shady areas or along bush margins). Mazus‘ beautiful, mostly white flowers (with tints of pale lilac) were out along the margins of the bush, where plants also seemed to be in better thrift, due to the presence of less detritus piling on top of them.

At the North Island’s easternmost tip, the population that I was taken to by a friend, Graeme Atkins, is probably the largest remnant of this critically-endangered herb. In this habitat, on a damp flat bordering a small stream, Mazus grows along the margin of the forest, where competition is limited from more aggressive exotic grasses and herbs. When we visited, Graeme mentioned that the extent of the Mazus had decreased since he was last at the site (one year prior), when it wended its way through much of the pasture adjoining the forest edge.

My suspicion is that this herb may benefit from periods when extreme levels of moisture create unfavourable conditions for competing species (notably pasture grasses), providing the kinds of open conditions that Mazus needs. In this sense, the forest edge may represent a kind of ‘refugium’ from which this plant can pulse outwards (“Our moment in the sun !”, as Graeme aptly names it, on behalf of Mazus) and retrench as environmental factors fluctuate.

Quite apart from the lessons that nature imparts, logic dictates that for a plant that occupies a layer up to just one inch above the ground, too much competition is not conducive to success within gardens or other plantings. As with many herbaceous groundcovers, Mazus is best suited to damp conditions, although it is reasonably tolerant of some drought in summer (in line with the fact that many swampy areas are not perpetually wet).

Its whitish flowers and attractive, matt foliage mark it out as a plant deserving of more attention in cultivation (as are its other two close relatives within the M. novaezeelandiae complex). This form, which was recognised as distinct in 1998, bears the epithet ‘hirtus’ (which is Latin for ‘hairy’) on the basis of the hairs on its leaf margins.