Plant profiles > Doodia

Family : Blechnaceae

Some native plants are especially capable of footing it with the demands placed upon their environments by human settlement. Where these occur, they serve as a nice reminder that nature is more resilient than we sometimes think. Indeed, some plants are so adept at co-existing with us that they become part of new 'hybrid' ecologies, formed of both man-made and natural elements.

There are fascinating 'hybrid' landscapes at various sites around New Zealand, where long periods of Māori occupation have given rise to distinctive ecologies - in which certain native plant species endure amidst the 'bones' of bygone settlements (even where these have been subsequently converted to pasture). One such place is at Ihumatao (known commonly as Otuataua Stonefields); a site that has a history of occupation extending back at least 800 years, and where the remnants of early Māori garden sites can still be seen.

Amongst the various stone structures that this area's first human inhabitants built1, several species of native plant find sufficiently favourable conditions to live. The rasp fern, Doodia australis, is one of these; pushing through shallow piles of stones at many points around this remarkable landscape. In this situation, it is reminiscent of the way in which the alpine hard fern (Blechnum penna-marina) grows through rocky habitats in more southerly areas of New Zealand.

New Zealand has five species of Doodia, all occurring naturally in warmer parts of New Zealand. Our species can effectively be divided into two groups, from an aesthetic standpoint. Doodia aspera, D. australis and D. milnei are comparatively substantial-looking plants, whilst D. mollis and D. squarrosa have more delicate foliage. As a general rule, our native species prefer good drainage within the garden.

Two of our native species of Doodia (D. australis and D. aspera) produce attractive reddish tinges in their new fronds; a characteristic that is unsurprising when one considers that Doodia is placed within the same family as Blechnum2 (Blechnaceae).

Doodia is a fairly small genus that occurs in New Zealand and Australia, and some far-flung points around the Pacific. Its unusual name commemorates a 17th-Century English botanist, Samuel Doody, who specialised in the study of ferns and their relatives.

Doodia australis
Rasp fern; Pukupuku

This tough fern is a common fixture in pasture and dry bush of northern areas, where (when encountered growing en masse - as it frequently does), the reddish-pink new fronds of Doodia australis can make for an arresting sight.

As one of the most resilient low-growing natives of northern New Zealand, it deserves to be more widely used by gardeners and landscapers, especially as it grows equally well in shade as it does in the sun (where it generally achieves its best foliage colour). One reason that it has not traditionally been considered in the first order of native ferns (for garden use) is that it can develop a slightly scruffy appearance, if old fronds are not trimmed off. However, this quibble is easily resolved with a modicum of maintenance.

In his fine work on the cultivation of non-woody natives, Lawrie Metcalf makes the astute observation that Doodia australis looks at its best when it is planted in reasonable numbers3. Furthermore, it achieves a striking effect when it is planted amongst rock, similar to how it naturally grows at Ihumatao (see the image to the left). Over time, individual plants of D. australis creep outwards, to form clumps.

It bears the common name 'rasp fern' because its fronds are somewhat harsh to touch. It is not unreasonable to assume that this is one factor in its comparative abundance in many disturbed habitats - as certain animal pests that decimate our native plants may find it unpalatable.

For a long time, Doodia australis was known under the name Doodia media, and it is by this title that one encounters descriptions of it in literature of a certain age. In addition to growing in the northern half of New Zealand, D. australis is also found in Australia.

 


Footnotes

  1. Some for housing, some for defence and others for the cultivation of the food crops that they brought to our shores.
  2. Several species of Blechnum are amongst our most brightly coloured ferns, as described in our plant profile on Blechnum.
  3.  'The Cultivation of New Zealand Plants'. Metcalf, L. 1993. Auckland : Godwit Press.