Urban areas have become epicenters for applied ecological and conservation research and policy. Yet, most urban areas have surprisingly little consolidated information about their biota, including species-at-risk and invasive species.

I used multiple data sources to compile a list of vascular plants for the greater metropolitan Toronto region. This data not only includes taxonomic information, but also global and national status ranks, growth from, native status, threatened status, abundance estimates and year of first observation for non-indigenous species.

The list includes 1937 taxa from 146 families, of which 822 are non-indigenous. The majority of native species were ranked as abundant and widespread both globally and provincially. However, non-indigenous species ranks were bimodal, likely to be either extremely restricted in the province, or very widespread.

This database provides a robust list of plant taxa in Canada’s largest city. It will inform global urban ecology analyses and local and regional management and policy.

The Toronto plant list, excluding non-vascular plants, was compiled from several different species lists and crossed referenced for taxonomic verification. Six different plant lists that are actively updated were used, including:

1. A list of species compiled through the Cadotte lab research within and around the city of Toronto (e.g., Arnillas & Cadotte 2019; Livingstone, Isaac & Cadotte 2020).
2. A list of the vascular plants for the Rouge National Urban Park, supplied by park staff, that included 861 taxa,
3. The plant list compiled by the Royal Ontario Museum -ROM (Royal Ontario Museum 2018) with the 1548 species recorded from the City of Toronto extracted.
4. A biological inventory of vascular plants provided by the Toronto Region Conservation Authority from their ravine and woodlot monitoring program, which included 790 species.
5. A list of plant observations was downloaded on October 21, 2019, from the Global Biodiversity Information Facility -GBIF (Global Biodiversity Information Facility 2020) from a polygon drawn around the greater Toronto area (-79.67285 43.48641,-78.84888 43.88364,-79.27734 44.0497,-79.80469 43.82026,-79.67285 43.48641), which included 1881 taxa.
6. A collation of natural history observations provided by Toronto resident Ken Sproule (http://toronto-wildlife.com/Plants/plants_family.html), which included 488 species.

Species from these sources were checked against the Taxonomic Name Resolution Service (http://tnrs.iplantcollaborative.org/index.html) and further uncertain designations were cross-referenced with the Canadensys database of vascular plants (https://data.canadensys.net/vascan/search?lang=en) to confirm presence in Canada and the currently accepted taxonomic name.

Species were then cross-referenced with the list of plants for the province of Ontario available through the Ministry of Natural Resources and Forestry’s Natural Heritage Information Centre (https://www.ontario.ca/page/natural-heritage-information-centre) to provide up-to-date information on the provincial and national rank and risk (COSEWIC) statuses as well as whether species are native or non-indigenous (introduced). Non-indigenous species are those not known to occur in the province of Ontario prior to European settlement (Myers & Bazely 2003).

I searched for species not found in Natural Heritage Information Centre with general online queries and in the USDA Plants database (https://plants.sc.egov.usda.gov) to confirm if species have been introduced or were cultivated and present in our region. For species rankings (Bachman, Nic Lughadha & Rivers 2018), I simplified the coding by combining extirpated (SE and GE) and likely extirpated (SH and GH) into SE and GE, respectively. I classified unrankable (SU and GU) and unassessed species as S? and G?, respectively. Furthermore, for species that have a range of rank values (e.g., S3S4) I took the more conservative conservation estimate and selected the lower bound to represent the potential conservation value. I retained the SNA and GNA, not applicable, designations for non-indigenous (introduced) species. I further performed web searches for each non-indigenous species to ascertain whether they were predominately spread as cultivated or domesticated species.

Each taxon was assigned one of nine growth form classes.

1.  Herbaceous: vascular plants lacking woody tissue.
2.  Graminoid: grass and grass-like plants in the Cyperaceae, Juncaceae, Juncaginaceae and Poaceae.
3.  Shrub: perennial woody plants with multiple stems, usually less than 5 metres tall.
4.  Tree: a woody plant with a single dominant stem, usually taller than 5 meters.
5.  Vine: a climbing plant with long stems that usually require a surface or another plant for physical support.
6.  Herbaceous/shrub: a plant that appears as an herbaceous plant in some conditions and as a shrub in others.
7.  Herbaceous/vine: a plant that appears as an herbaceous plant in some conditions and as a vine in others.
8.  Shrub/tree: a plant that appears as a shrub in some conditions and as a tree in others or is at the boundary between shrub and tree growth forms.
9.  Shrub/vine: a plant that appears as a shrub in some conditions and as a vine in others.

In addition to species ranks and risk status, estimates of abundance from the number of occurrences of species in the ROM and the GBIF lists were included. I also created a composite abundance measure from the ROM and GBIF estimates by scaling both sets to be between 1 and 100 and taking the average of the two. Either the scaled ROM or GBIF estimates were used if the other was missing. I rounded the combined estimates to the nearest whole number. Further, the first date of observation for non-indigenous (introduced) species in the ROM list was also included.

While the plant list includes species from both Pteridophytes (clubmosses, ferns and horsetails) and Spermatophytes (seed plants), the sources used more consistently recorded Spermatophytes, and so the list of Pteridophytes is likely to be incomplete. Furthermore, subspecies, varieties, etc., were likely to have been inconsistently identified or included, and so the taxa list underrepresents the full number of these subspecific designations present in the city. It’d be prudent to analyze patterns at the species level only.