How many plants are in New Zealand?

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How many plants are in New Zealand?

I gave a talk on “Understanding and valuing our plants” at the recent open day of Otari-Wilton’s Bush in Wellington. I’m very interested in why New Zealand’s native species might be valued. I am hoping you can help me think about that – I welcome your input; look out for an upcoming blog post. But before that, some background on the numbers of plants in New Zealand.

The numbers of plants in New Zealand

Some 8500 different kinds of plants are indigenous to New Zealand. “Indigenous” indicates they are present in New Zealand without the intervention of humans. This total is made up of 2030 seed plants, 201 ferns and lycophytes, 480 mosses, 610 liverworts, 1800 lichens, and over 3000 (unicellular and multicellular) algae. These figures principally come from the recently published New Zealand Inventory of Biodiversity.

Kahikatea (Dacrycarpus dacrydioides) is the tallest of New Zealand’s indigenous plants. It is one of the more than 1600 seed plants that are endemic to New Zealand, being indigenous here but nowhere else in the world. Photo Leon Perrie CC BY-NC.
Kahikatea (Dacrycarpus dacrydioides) is the tallest of New Zealand’s indigenous plants. It is one of the more than 1600 seed plants that are endemic to New Zealand, being indigenous here but nowhere else in the world. Photo Leon Perrie CC BY-NC.

Many of these indigenous plants are endemic to New Zealand; that is, only found here. For example, c. 80% of the indigenous seed plants are endemic, and c. 45% of the ferns and liverworts.

Humans have greatly impacted New Zealand’s plants. The effects are best understood among the vascular plants (seed plants plus ferns and lycophytes).

According to the latest assessment, 42% of vascular plants are of some conservation concern. That seems alarmingly high, but it does include species with naturally small populations. 10% are formally Threatened. Comparing conservation rankings for vascular plants over time, it appears the trend is steady, if not worsening. Certainly, the collective conservation status of our vascular plants is not substantively improving; “clean green” New Zealand is not yet in full-blown remediation.

Stereocaulon ramulosum is a common New Zealand-indigenous lichen. I suspect few New Zealanders would know it, which is symptomatic of the attention given to lichens, even though they contribute significant biomass to many ecological communities. Photo Leon Perrie CC BY-NC.
Stereocaulon ramulosum is a common New Zealand-indigenous lichen. I suspect few New Zealanders would know it, which is symptomatic of the attention given to lichens, even though they contribute significant biomass to many ecological communities. Photo Leon Perrie CC BY-NC.

Uncertainty reins among other the plant groups; 54% of New Zealand’s lichens (975 ‘species’) are so poorly known that they cannot be assigned a conservation ranking. Many of New Zealand’s seaweeds have been recorded only a handful of times. Third rate understanding cannot enable first class environmental management.

Anyone visiting New Zealand’s coast is likely to have seen Neptune’s necklace (Hormosira banksii). It is a very common, indigenous brown seaweed. But many New Zealand seaweeds are only poorly known. Photo Leon Perrie CC BY-NC.
Anyone visiting New Zealand’s coast is likely to have seen Neptune’s necklace (Hormosira banksii). It is a very common, indigenous brown seaweed. But many New Zealand seaweeds are only poorly known. Photo Leon Perrie CC BY-NC.

Habitat loss and introduced browsers, pests, and competitors have all taken their toll on New Zealand’s indigenous plants.

Our indigenous plant species are now outnumbered by plants, mostly seed plants, introduced from elsewhere in the world. A few of the introductions are productive, some are pretty, but many would appear to have few redeeming features, at least in the New Zealand context. Among seed plants, there are now more weedy species than natives, and a very-roughly estimated 25 000 species of seed plants are cultivated in New Zealand.

African club moss (Selaginella kraussiana) is an introduced lycophyte (and not a moss). It is very invasive, even into relatively undisturbed indigenous forests. It carpets the ground, suppressing the regeneration of indigenous plants. WELT P026410. Photo Leon Perrie. © Te Papa CC BY-NC-ND.
African club moss (Selaginella kraussiana) is an introduced lycophyte (and not a moss). It is very invasive, even into relatively undisturbed indigenous forests. It carpets the ground, suppressing the regeneration of indigenous plants. WELT P026410. Photo Leon Perrie. © Te Papa CC BY-NC-ND.

New Zealand evidently has a lot of indigenous plants.  Are they valuable to you?  Why?

More information:

More information on the New Zealand Inventory of Biodiversity (Volume 3), which includes the plants.

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

Threatened and uncommon bryophytes of New Zealand (2010 revision), abstract.

Conservation status of New Zealand lichens, abstract.

Insights from natural history collections: analysing the New Zealand macroalgal flora using herbarium data.

4 Comments

  1. Leon, its heartbreaking to see African club moss proliferating along public walkways all over Auckland. With enough volunteers, one could envisage it all being removed before spread deep into our native forests. Its tempting to envision NatureWatch evolving into a platform for projects which see ‘Friends of XYZ Reserve’ organise and remove weeds !

    1. Author

      Hi David,
      I agree that some weed infestations look unmanageable, but with effort a lot of good can be done for our indigenous biodiversity, at least for priority areas. I think some of the founders of NatureWatch do envisage it being used as you describe – to monitor weed (and native) species, and organise the management of those species around that monitoring. Hopefully we’ll see some good examples emerge soon.
      Kind regards, Leon

  2. Hi Leon, this is a subject dear to my heart, and I would be interested in this conversation. Divaricating plants are terrific, yet little research exists.
    I am also passionate about weed control, and often tell people that we have more weeds than native species now – and they are aghast. The big question is, what do we do about it? Jo

    1. Author

      Hi Jo,
      Good question, and I’m interested to hear what others think can be done. There is lots of weeding work to do, potentially in conjunction with organisations like Weedbusters (http://www.weedbusters.org.nz/). (And I note David’s comments above about community groups looking after local reserves.) But we could also be vigilant against new weeds. Although our borders are now reasonably tight, there is a large reservoir of introduced plants being cultivated in NZ from which new weeds will emerge. If you find a plant newly appearing in an area, work out what it is (with, e.g., http://naturewatch.org.nz/), and if it is a weed, take action!
      Kind regards, Leon

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