Data version

The data currently served is version 2026.10.13.

The version is the date of the last data operation run on the database (an import, a purge, a migration), with a .2, .3… suffix when several ran the same day. Every API response states it, in meta.dataset_version and in the X-Trefle-Data-Version header; GET /api/v1 returns it with its release date, and GET /api/v1/changelog lists the previous versions and what each one changed.

Cite the version together with the date you accessed the data (replace YYYY-MM-DD below). Community corrections are accepted one by one between data operations, so the access date is what pins them. If your queries spanned several days, give the range, and keep the dataset_version of the responses you stored.

DOI

DOI pending. Trefle's Zenodo deposit is not live yet; cite the plain URL below in the meantime and update the citation once a DOI is assigned.

Citation formats

Each block below cites Trefle and, after it, the upstream sources whose records Trefle serves (see Upstream credits).

Plain text

Trefle (2026). Trefle: a global plants API, data version 2026.10.13. https://trefle.io (accessed YYYY-MM-DD) — data licensed CC-BY-4.0.

Govaerts, R., Nic Lughadha, E., Black, N., Turner, R. & Paton, A. (2021). The World Checklist of Vascular Plants, a continuously updated resource for exploring global plant diversity. Scientific Data 8, 215. https://doi.org/10.1038/s41597-021-00997-6 ; and POWO, Plants of the World Online, facilitated by the Royal Botanic Gardens, Kew. https://powo.science.kew.org/

GBIF Secretariat. GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org.

Kattge, J. et al. (2020). TRY plant trait database – enhanced coverage and open access. Global Change Biology 26, 119–188. https://doi.org/10.1111/gcb.14904 — credit the TRY initiative and its contributing datasets.

WFO. World Flora Online. Published on the Internet; http://www.worldfloraonline.org.

IPNI. International Plant Names Index. Published on the Internet http://www.ipni.org, The Royal Botanic Gardens, Kew, Harvard University Herbaria & Libraries and Australian National Herbarium.

Pl@ntNet, https://plantnet.org — each image keeps the author and licence returned with it (the `copyright` field of the API).

APA

Trefle. (2026). Trefle: a global plants API (Version 2026.10.13) [Data set]. Retrieved YYYY-MM-DD, from https://trefle.io

BibTeX

@misc{trefle2026,
  title = {Trefle: a global plants API},
  author = {{Trefle}},
  year = {2026},
  version = {2026.10.13},
  url = {https://trefle.io},
  urldate = {YYYY-MM-DD},
  note = {Data licensed CC-BY-4.0}
}

@article{govaerts2021wcvp,
  author = {Govaerts, Rafaël and Nic Lughadha, Eimear and Black, Nicholas and Turner, Robert and Paton, Alan},
  title = {{The World Checklist of Vascular Plants, a continuously updated resource for exploring global plant diversity}},
  journal = {Scientific Data},
  year = {2021},
  volume = {8},
  pages = {215},
  doi = {10.1038/s41597-021-00997-6}
}

@article{kattge2020try,
  author = {Kattge, Jens and Bönisch, Gerhard and Díaz, Sandra and Lavorel, Sandra and Prentice, Iain Colin and others},
  title = {{TRY plant trait database – enhanced coverage and open access}},
  journal = {Global Change Biology},
  year = {2020},
  volume = {26},
  number = {1},
  pages = {119--188},
  doi = {10.1111/gcb.14904}
}

RIS

TY  - DATA
AU  - Trefle
TI  - Trefle: a global plants API
PY  - 2026
ET  - Version 2026.10.13
UR  - https://trefle.io
Y2  - YYYY-MM-DD
N1  - Data licensed CC-BY-4.0
ER  - 

TY  - JOUR
AU  - Govaerts, Rafaël
AU  - Nic Lughadha, Eimear
AU  - Black, Nicholas
AU  - Turner, Robert
AU  - Paton, Alan
TI  - The World Checklist of Vascular Plants, a continuously updated resource for exploring global plant diversity
JO  - Scientific Data
PY  - 2021
VL  - 8
SP  - 215
DO  - 10.1038/s41597-021-00997-6
ER  - 

TY  - JOUR
AU  - Kattge, Jens
AU  - Bönisch, Gerhard
AU  - Díaz, Sandra
AU  - Lavorel, Sandra
AU  - Prentice, Iain Colin
TI  - TRY plant trait database – enhanced coverage and open access
JO  - Global Change Biology
PY  - 2020
VL  - 26
IS  - 1
SP  - 119
EP  - 188
DO  - 10.1111/gcb.14904
ER  - 

Upstream credits

Trefle's compilation, structure and community corrections are published under CC-BY-4.0. Redistributing Trefle data keeps every upstream source's own credit intact — see the sources listed on the About page and the per-record sources array returned by the API.

These upstream sources currently contribute records to Trefle (taxonomic links and trait values counted in the database, so the list follows the data). Their licences require that you credit them alongside Trefle:

A handful of values also come from pfaf (24), flora_of_north_america (10), missouri_botanical_garden (8), flora_iberica (6), USDA (2), and treesandshrubs (1); the per-record sources array and GET /api/v1/species/{id}/facts say which.