Goodbye to the lettuce liverwort – it’s going extinct

Goodbye to the lettuce liverwort – it’s going extinct

A highlight of my recent South Island fieldwork was helping to survey the last remaining New Zealand population of the liverwort Petalophyllum preissii.  It’s a distinctive looking plant, a bit like a little lettuce, and about the size of a fingernail.

The liverwort Petalophyllum preissii. Photo Leon Perrie. © Te Papa.
The liverwort Petalophyllum preissii. Photo Leon Perrie. © Te Papa.

Seeing it was special because I likely won’t have the opportunity again.  You’ll probably never have the chance to see it alive in New Zealand either, unless there is a radical change in its fortunes.

Led by Landcare Research’s liverwort expert, David Glenny, we found only 36 plants, at a site near Kaikoura.  That’s the entire New Zealand population.  Numbers have nearly halved since it was last surveyed several years ago.

A cluster of Petalophyllum preissii plants, with my finger for scale. Photo Leon Perrie. © Te Papa.
A cluster of Petalophyllum preissii plants, with my finger for scale. Photo Leon Perrie. © Te Papa.

What’s happening?

Populations of Petalophyllum preisii elsewhere in New Zealand have completely disappeared.  The reasons for their decline are unclear. At Kaikoura, David Glenny thinks it is being shaded out by introduced grasses, particularly Festuca rubra.

The kākāpō (Strigops habroptilus) is a threatened New Zealand species that gets lots of help. It even has its own website: Other species don’t get the same attention. There are far fewer individuals of Petalophyllum preissii in New Zealand than there are kākāpō. Specimen registration number OR.009487. Photo © Te Papa CC BY-NC-ND.
The kākāpō (Strigops habroptilus) is a threatened New Zealand species that gets lots of help. It even has its own website: Other species don’t get the same attention. There are far fewer individuals of Petalophyllum preissii in New Zealand than there are kākāpō. Specimen registration number OR.009487. Photo © Te Papa CC BY-NC-ND.

Other than the cutting of some surrounding scrub, Petalophyllum preissii does not seem to be receiving any assistance.  It does occur in Australia and, although uncommon there too, perhaps that’s the reason New Zealand’s plants are being allowed to drift to extinction.

Is this case unusual?

While the continued existence of Petalophyllum preissii in New Zealand is especially precarious, lots of other native plants are faring poorly too.  235 different kinds of our native vascular plants (seed plants, ferns, & lycophytes) are formally Threatened; that’s 10%.  A further 683 are At Risk (28%).  These native plants species (or subspecies or varieties) have declined since humans arrived in New Zealand or are naturally rare.  Either way, there is now real concern that we and our introduced menagerie might eliminate them, without care and intervention.

Is it getting better?  The latest assessment for vascular plants (link below) referenced just 2 species that “experienced an actual improvement in their status through management”.  The 235 kinds of vascular plants regarded as Threatened was up from 180 in the assessment four years previous.

It is arguable whether ‘clean and green’ New Zealand is living up to its reputation when it comes to looking after its indigenous vascular plants.

If this is the treatment of our ‘big’ plants, what attention might we afford our ‘little’ plants like Petalophyllum preissii and its liverwort brethren?  Being small, they are easily overlooked as part of our natural heritage.

Who cares and who is responsible?  Maybe the philanthropic Endangered Species Foundation will ride to the rescue.

Website of the Endangered Species Foundation.

What do you think?  Should New Zealand try to save its population of Petalophyllum preissii?

More information

Do we need New Zealand’s indigenous species? Te Papa blog post.

How many plants are in New Zealand? Te Papa blog post.

Plant collecting in south Canterbury and Marlborough. Te Papa blog post summarising the other aspects of our trip where we saw Petalophyllum priessii. For the record, we didn’t collect a specimen of it; it’s too rare for that.

Conservation status of New Zealand hornworts and liverworts, 2014. Department of Conservation report (pdf).

Conservation status of New Zealand indigenous vascular plants, 2012. Department of Conservation report (pdf).

Environment Aotearoa 2015, report by Ministry for the Environment (pdf).  See figure 41 on page 109 which indicates the number of species assessed as Threatened is increasing.


  1. I was the Greenhouse Manager for the Biological Sciences Dept at California State University, Fullerton. I developed propagation protocols for many rare plants. If you have a teaching collection at any of the colleges and universities, perhaps someone there can bring some of these plants into cultivation. If so and they build up the numbers, any institution should be able to request material and it would be sent with permits.
    Also, attempts should be made to get it into sterile tissue culture, which would provide a way to have larger numbers built. Culture vessels can be sent anywhere and any plant quarentine official would wave them through as they would be pest free. The more people that have this interesting plant, the better.
    “Conservation thru propagation and dissemination.”
    Has anyone seen if it produces sporophytes? If so, spores can be collected and cryopreserved.
    Hope this helps.

    1. Author

      Thanks Leo. Good suggestions. I’m going to contact some of the botanical gardens to see if they are able to have a go. I don’t know much about sterile tissue culture, but it could be a very useful approach. The plants weren’t making sporophytes when we visited, but perhaps that was just the wrong time of the year.

  2. Do we have any botanic gardens in NZ who are practicing ex-situ conservation of bryophytes or lichens?

    An excellent read as always Leon. Thanks for bringing attention to this.


    1. Author

      Hi Alex,
      I don’t know of any NZ botanic gardens (purposefully) growing bryophytes or lichens. But it would certainly be a useful thing to do. It is something I’ll be suggesting to Otari, here in Wellington. In the meantime, David is trying to propagate a similar species, as a way of testing what is required.

  3. Hi Leon
    I too think we need to care about the little guys of all colours, shapes and textures, and help raise public awareness of their plight, along with the great work that you and other NZ botanists are doing.

    This week I was fortunate to visit the new Darwin Centre at NHM London. Love how they’ve built an elegant, interpretive interface to their ‘back-of-house’ collections and research labs. Your blog, so effectively and urgently titled, got me thinking that the lettuce liverwort would be a great candidate for a herbarium cameo profile. I have lots of photos, and can explain!

    1. Author

      Thanks Karen. I look forward to hearing more.

    2. I hope that some can be taken for ex situ conservation and dissemination. Looks similar to what I knew as Anthoceros or Hornwort from the long sporophytes

  4. I agree that in this instance application of the precautionary principle is highly appropriate. However, I would not like that application to detract from the need for (perhaps fruitless, admittedly) additional search and survey as a component of management strategies for bryophytes. In this, and every, instance fruitless searches would validate the precaution. Fruitful searches may facilitate reprioritisation of funds, to other populations, or maybe other species, however is appropriate. I hope this advocacy is fair enough. As I say, I enjoy your blogs,

    1. Author

      I agree that a lot more surveying is needed! It’s embarrassing how little New Zealand knows about some of its inhabitants, liverworts among them. While recognising the distinctive Petalophyllum is relatively easy, identifying many of the others takes specialist skills, and we probably don’t have enough such skills in the country.

      Demonstrating the benefits of more searching, something I didn’t mention in the blog post about our recent South Island fieldwork was that Peter discovered a second NZ site for the liverwort Andrewsianthus hodgsoniae, nearly 50 years and several hundred kilometres away from its first site.

  5. I care. But how do we know for 100% sure that the Kaikoura population is the last? Ought we not tap LINZ for environmental data and with the known and historical occurrences attempt to predict where Petalophyllum might have lived, and still be living in NZ?If we can then verify its absence from all potentially occupied areas I would be more comfortable about claiming the known population is the 100% last. As far as I am aware, a predictive, data-based approach has not yet been applied to informing search and survey for observation-poor threatened bryophytes in New Zealand. I think it is time that changed, and this species would be an excellent place to start.
    Love your blogs.

    1. Author

      Hi Matt,
      Thanks. You’re right that this is the last *known* population in New Zealand. Doing some niche-modelling work to prioritise other places to search is a good idea. I don’t know if the Department of Conservation does that. (It is not a skill we have at Te Papa.) But in the meantime, the Kaikoura plants are all we’ve got. I wonder if active intervention should outweigh hoping there are additional as-yet-undiscovered populations.

    2. Good point – we successfully used this approach to find new sites of a ground weta.

      This is a project the Endangered Species Foundation would be interested in helping. Who would be best to speak to? David or Leon?

    3. Author

      Hi Mike,
      David is the best person to talk to.

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