Tag Archives: maidenhair spleenwort

More rare maidenhair spleenwort.

16 March 2009 – 11.18am

The rare, tetraploid maidenhair spleenwort  (Asplenium trichomanes subsp. quadrivalens) has only recently been rediscovered in New Zealand.  Several people have contacted me with possible additional sightings. As described by the Scoop website, Jack Ritchie had a maidenhair spleenwort self-sow on a rock used to construct a water feature in his nursery, Tree Guys, in Otane.

Jack took us to the local farm where the rock was sourced from, and without too much effort we found a good population: about 70 plants growing on limestone outcrops in pasture.

Asplenium trichomanes subsp. quadrivalens

Tetraploid maidenhair spleenwort.

These rocks are host to several plants of tetraploid maidenhair spleenwort.

These rocks are host to several plants of tetraploid maidenhair spleenwort.

Lara Shepherd (Massey University) and I collected a few samples, and confirmed through analyses of their spores and DNA that they were the tetraploid maidenhair spleenwort rather than the common hexaploid maidenhair spleenwort.

DNA sequence data. The highlighted position is one of several DNA sites found by Lara that differ between the tetraploid (upper two samples) and octoploid (lower two samples) maidenhair spleenworts.

DNA sequence data. The highlighted position is one of several DNA sites found by Lara that differ between the tetraploid (upper two samples) and hexaploid (lower two samples) maidenhair spleenworts.

There is plenty of similar habitat in the region, so the tetraploid maidenhair spleenwort could well be much more widespread. We need to find more than 250 individuals to lift it out of the Nationally Critical conservation category, which I am hopeful we will achieve with more searching.  Ideally, it will turn out to be sufficiently common that it doesn’t even need to be on the threatened list.

Thanks to Jack Ritchie and everyone else who has contacted me about the maidenhair spleenwort. I have several other promising leads to follow-up when I am next able to escape the office.

If you would like to see a tetraploid maidenhair spleenwort for yourself, then visit Jack Ritchie. He is a very knowledgeable and enthusiastic plant-person, and his tetraploid maidenhair spleenwort is the only one I know of in ‘captivity’. Jack’s Tree Guys nursery is in Otane, on the main road between Waipukurau and Hastings.

By Leon Perrie | Posted in Ferns, Field trips, Plants | Also tagged , , , , , | Comments (1)

Identifying maidenhair spleenwort ferns.

24 February 2009 – 2.00pm

The maidenhair spleenwort is a spleenwort fern (Asplenium) that (supposedly) looks like a maidenhair fern (Adiantum, see below). The 600 or so of the world’s spleenworts are characterised by having their reproductive structures in lines away from the margins of their fronds’ undersides.

asplenium_trichomanes_sori_edit

The reproductive structures (the sori, made up of the sporangia which contain the spores, and their protective indusia) of maidenhair spleenwort, on the underside of a frond.

Two maidenhair spleenworts occur in New Zealand. They look very similar, but one has four sets of chromosomes (tetraploid) and the other six (hexaploid). This difference in chromosome number means they cannot interbreed. In New Zealand, the hexaploid is common, but the tetraploid is rare, only being known from the Hawke’s Bay, and only recently being rediscovered. Outside New Zealand, the hexaploid is rare, being known from only a few places in Australia, while the tetraploid is common and widespread around the world.

Tetraploid and hexaploid plants of maidenhair spleenwort.

Tetraploid and hexaploid plants of maidenhair spleenwort.

distributionmaps

The distributions of the maidenhair spleenworts in New Zealand.

  

Maidenhair spleenworts are most commonly found on limestone rock. They can be out in the open, or under semi-shade, but usually in fairly dry conditions. They often hold their fronds erect, whereas other ferns growing from rock usually have pendulous fronds.

Open, limestone outcrops; a habitat for maidenhair spleenworts.

Open, limestone outcrops; a habitat for maidenhair spleenworts.

The taxonomy of New Zealand’s maidenhair spleenworts is still being researched. The tetraploid may be referable to Asplenium trichomanes subsp. quadrivalens. The correct scientific name for the hexaploid, the most common maidenhair spleenwort in New Zealand, is presently unclear.

Maidenhair spleenworts can be distinguished from other New Zealand ferns by the combination of their typical spleenwort reproductive structures (see above), and their frond stems which are almost black, almost smooth (without hairs and with only a few scales), and undivided (i.e., the stems do not branch). Similar-looking  ferns in New Zealand are described below.

 
Necklace fern, Asplenium flabellifolium.
A spleenwort or Asplenium fern like the maidenhair spleenworts can be most obviously distinguished from the maidenhair spleenworts by its green stem.

 

asplenium_flabellifolium1

Necklace fern, Asplenium flabellifolium.

Maidenhairs, Adiantum.
The maidenhairs are most obviously distinguished from the maidenhair spleenworts by the branching stems of their fronds. The Small maidenhair (Adiantum diaphanum) can sometimes have unbranched frond stems, but it, like all maidenhairs, can be reliably distinguished by having the reproductive structures on the margins of their fronds’ undersides.

A maidenhair fern, Adiantum fulvum.

A maidenhair fern, Adiantum fulvum.

Button fern, Pellaea rotundifolia.
The brown and scaly frond stems and reproductive structures on the margins of their fronds’ undersides distinguish button ferns from the maidenhair spleenworts.

The Button fern, Pellaea rotundifolia.

The Button fern, Pellaea rotundifolia.

Blechnum ferns.
Like most Blechnum ferns, Creek fern (Blechnum fluviatile) and Lance fern (Blechnum chambersii) have very different looking fertile and sterile fronds. Those fronds that are making spores have much narrower segments, are held more erect, and are black or brown (they are not dead despite their lack of greenness!).

blechnum_fluviatile_chambersii

Blechnum chambersii or Lance fern (left) and Blechnum fluviatile or Creek fern (right). The blue arrows indicate fertile fronds.

 

We are still interested in learning more about the maidenhair spleenworts in the southern North Island (south of, and not including, the Waikato). I would be very grateful for notification (and a photo) if you think you have found maidenhair spleenwort in the southern North Island. Please either email (leonp@tepapa.govt.nz), phone (04 381 7261), or write me (Leon Perrie, Te Papa, PO Box 467, Wellington).

By Leon Perrie | Posted in Ferns, Plants | Also tagged , , , | Comments (5)

Rare fern rediscovered.

21 October 2008 – 4.45pm
I’m one of the Botany Curators at Te Papa, and ferns are one of my specialties.  New Zealand has about 200 native ferns, and some of them are very rare.  We recently rediscovered one rare fern that had been ‘lost’.  I was beginning to wonder if it had become extinct, but fortunately it has not.  Still, the known total of individuals is still only 9, and this population is only a goat-lunch away from extinction!
Me, on top of the Ruahine Ranges. No rare ferns sighted up here, but interesting nonetheless.

Me, on top of the Ruahine Ranges. No rare ferns sighted up here, but interesting nonetheless.

The rediscovered fern is a maidenhair spleenwort.  It had been definitively identified from just three New Zealand sites, all in Hawke’s Bay, and all dating to the 1950′s.  The localities of these three sites were not precisely recorded, and no one I talked to knew of a living population.   I enlisted the help of the Manawatu Botanical Society to search one of these sites (the most precise one, which involved searching several square km rather than several tens of square km).  I wasn’t very optimistic, given the amount of time since it had been previously collected and that I had already looked at a number of similar Hawke’s Bay sites.  But, we found it – 9 plants in one very small area. 

There is another maidenhair spleenwort in NZ, and it is quite common.  These two maidenhair spleenworts look similar, but they have different chromosome numbers; the common one has six sets of chromosomes while the rare one has four sets.  This kind of difference is usually treated at the subspecies or even species level in ferns.   Unfortunately, the present taxonomy, or formal scientific naming, for these ferns is not adequate.  We hope to sort this out in the next year or so.  They have both been called Asplenium trichomanes, but this fern does not occur in NZ (at least when interpreted in a narrow sense).  The rare maidenhair spleenwort in NZ has also been called Asplenium trichomanes subsp. quadrivalens; whether this is correct remains to be established.
Maidenhair spleenwort. This is the rare species, but the common one looks very similar.

Maidenhair spleenwort. This is the rare species, but the common one looks very similar.

The two maidenhair spleenworts usually occur on or near limestone.  They can be distinguished from all other ferns in NZ by their undivided, black, almost smooth stems, and by having their reproductive structures in lines away from the margins of the undersides of their leaves.  This particular arrangement of the reproductive structures characteristics all of the spleenwort (Asplenium) species, of which there are about 20 in NZ (and some 600 in the world).

I’d be interested in learning of additional maidenhair spleenwort sites in Hawke’s Bay.  Both species of maidenhair spleenwort have been recorded from the Hawke’s Bay, so any new finds may be the rare or the common species.  I would need to closely inspect them to be sure.  But, please, do not remove them from the wild!  Email (leonp@tepapa.govt.nz) or phone (04 381 7261) me the locality details.

Te Papa’s Collections Online includes a photo of a maidenhair spleenwort specimen collected from the Hawke’s Bay in 1881 (it’s the common species, rather than the rare one).  The New Zealand Plant Conservation Network also has more information about maidenhair spleenworts.

By Leon Perrie | Posted in Collections Online, Ferns, Plants | Also tagged , , , , | Comments (3)
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