Why we don’t include putative (tag-name) species on the NZPCN website and how to find out more about them.
Putative species, more commonly referred to as tag-name plants are indigenous plants that field botanists or taxonomists suspect are different to any existing named plants. These tag-name plants typically appear to be different species but have not been studied by systematists or taxonomists. Therefore, they could be considered a working taxonomic hypothesis. Over time, some of these potentially distinct entities are each given a ‘tag’ name which acts as a surrogate botanical name and can help provide consistency of identification until they are properly studied. Tag-names applied to these putative species are commonly associated with the area the entity was found in or a distinctive feature of its morphology. Sometimes tag-named plants are given a threat status before they are properly studied and named, as these plants frequently have very small populations or occupy threatened habitats. Having a threat status represents a conservative approach to avoid potential extinction before the proper taxonomic work is done. Although some tag-named plants might eventually be incorporated into another species concept, it is thought better to take a cautious approach when it comes to plant conservation.
The New Zealand Plant Conservation Network does not produce factsheets for tag-name plants because there is sometimes disagreement between field botanists, systematists and taxonomists about which ones are likely to be classified as distinct entities. Without a foundation of taxonomic research these arguments are anchorless; similarly, without a taxonomic description to refer to, it would be difficult to complete a factsheet for a tag-name species. Furthermore, as these tag-name plants are essentially untested hypotheses the Network does not want to produce material that could be misused as a publication on the tag-name species before the proper taxonomic research is undertaken.
Although tag-names can be useful for identifying species groups where more taxonomic research is required and to highlight potential conservation issues, they have complications. Examples of problems with tag names include:
- Multiple tag-names being applied to the same entity.
- Tag-names being applied indiscriminately leading to the number of plant species in New Zealand being artificially inflated.
- Tag-name concepts being taken uncritically, thereby creating a species without conducting the proper taxonomic research.
- Suspicion about their veracity that could undermine their use in, for example, district and regional plans or in Environment Court proceedings.
This plant had the tag name Craspedia (a) (CHR 511522; Clutha River) until it was formally described by Ilse Breitwieser and Kerry Ford in 2022 as Craspedia argentea. Photo: John BarklaFor conservation practitioners the existence of tag-name plants and the lack of resources to scientifically describe them, creates a bit of a conundrum. How do you find and identify the plants without knowing what to look for? Fortunately, some resources do exist to help narrow down what you’re looking for when it comes to tag-name species. The New Zealand Threat Classification System lists tag-name species in its website and for plants these will be accompanied by a herbarium specimen number. This herbarium number is there as a placeholder for the tag-name to say, “this is what we mean by tag-name x,” much like the role of a type specimen for a fully named species. Searching for the herbarium specimen number in the relevant herbarium database will provide more information on what to look out for in the wild. You can search the Allan Herbarium (CHR) database, the Wellington Herbarium (WELT), and the Auckland herbarium (AK).
Some publications have also listed and described tag-name plant species. For example, Conserving the plants of eastern South Island limestone Ngā tipu ō te pākeho lists the tag-name species because the existence of so many other limestone plants is precarious. Likewise, trawling through old Botanical Society Journal articles can also provide rudimentary descriptions of some tag-name plants. Many Botanical Society Journal articles can be found here. Lastly, some NZPCN species factsheets contain a discussion of tag-name species under the “Similar taxa” or “Taxonomic notes” sections. For example, the factsheet for the fern Christella dentata contains a discussion of a “geothermal race.”
As research is completed on tag-name plants in New Zealand, the NZPCN taxonomic subcommittee will assess the research publications and add species to the NZPCN factsheet pages as new species are formally recognised and published. For example, in 2023 five new species of woolly heads (Craspedia), that had previously been treated as tag-name entities, had names published as part of taxonomic research and were recognised by NZPCN and given their own factsheets.