In the early years of the 20th Century, a native ‘weed’ crept uninvited into enemy territory; an environment that embodied human control and represented the opposite of biological diversity – the bowling green. Efforts to control the infestation at one club (the Caledonian Club in Dunedin) only proved to encourage it, and later came to be regarded as ideal practice when ‘cotula’ (the old name for this creeping herb) became embraced as an excellent plant for bowling greens.
In the intervening decades, Leptinella has been used on bowling greens over much of New Zealand; particularly in cooler southern regions, where members of the genus find more suitable growth conditions. I presume that its popularity for this purpose is the reason for the intriguing composition of holes that we encountered on the Southland coast (shown below), wherein it would appear that wild Leptinella plugs were harvested for use in recreational turf. One of the two major forms used for this purpose, Leptinella dioica, has also been widely planted within gardens, for its attractive, ferny foliage and the dense groundcover that it forms.
New Zealand’s 25 species of Leptinella make up the bulk of the genus, which consists of c. 33 species. They occur in a wide range of mostly open habitats, from alpine scree to damp grassland and coastal cliffs. Several species are highly threatened in the wild (an occupational hazard for ground-hugging herbs), including the extreme case of L. filiformis, which was until recently considered extinct in all of its original habitats (but which has been rediscovered in inland Marlborough).
Aside from L. dioica, a number of other species possess significant potential for cultivation, including the northwest Nelson endemic, L. calcarea, the highly threatened L. rotundata, L. squalida, L. filiformis and Leptinella serrulata (which is often sold incorrectly as L. ‘Platt’s Black’). In general, Leptinella species perform best where sufficient fertility is available and they are not permitted to dry out excessively.
This enigmatic little plant is easily distinguishable from its relatives by the round leaves that provide it with its specific epithet. It is one of our rarer native plants, occupying isolated cliff habitats along the west coast of Auckland and Northland. That said, L. rotundata‘s status has changed over the last few years as new populations have been discovered – including the recent rediscovery of plants within the Auckland region, where none had been seen for decades.
L. rotundata finds its opportunities on the often unstable fringe where land meets sea, such as the boulder-strewn cliff where I have viewed it on Auckland’s west coast. One noticeable aspect of its growing station was that there was relatively little direct sunlight on the plants. This reinforced my observation of this plant from cultivation, wherein it performs best in a position in which some open shade is afforded in the hottest periods of the day.
The bright green hue of the leaves makes it an attractive groundcover for gardens, where we have found it better suited to growing in combination with other groundcovers (rather than in large swathes by itself). I have also seen it put to particularly good use in the centre of Auckland, where it was planted to trail over the sides of a pot within the Britomart precinct. L. rotundata was discovered (to science) by one of New Zealand’s foremost early botanists, Thomas Frederick Cheeseman, who found it on Auckland’s west coast at the beginning of the 20th Century.