Southern Ontario Vascular Plant Species List

Nomenclature
The nomenclature used for this listing of 2,326 plant species, subspecies and varieties, is in
accordance with the Ontario Plant List (OPL), 1998. This publication has been used as the
standard reference for plant names by the Ontario Ministry of Natural Resources for the past
decade.
There have been many nomenclatural innovations in the past several years since the publication
of the Ontario Plant List that are not fully reflected in this listing. However, the OPL includes a
listing of many of the synonyms that have been used in the botanical literature. For a more up to
date listing of scientific plant names visit either of the following web sites:
Flora of North America - http://www.efloras.org/flora_page.aspx?flora_id=1
NatureServe - http://www.natureserve.org/explorer/servlet/NatureServe?init=Species
PLANTS Database - http://plants.usda.gov/index.html
For those of you who have utilized the Natural Heritage Information Centre (NHIC) plant species
list for Ontario, notice that there have been some major rearrangements in the taxonomy. For
example, most of the Aster species have now been put into the genus Symphyotrichum, with a
few going into the genus Eurybia. In addition, the Flat-topped White Aster is now classified as
Doellingeria umbellata. The genus Scirpus has also been split into different genera, with just a
few remaining species being retained in the original genus. Most of the species originally in
Scirpus are now described under the genus names of Schoenoplectus, Trichophorum or
Bolboschoenus.
With the use of DNA and other chemical analysis, botanical researchers will probably rearrange
many more species in the near future.
Since additional plant species have been observed for the first time in the province (after 1998),
41 new entries have been included in this listing. This has been done to keep the listing more
compatible with other Ontario plant listings. These include the addition of new species to the
provincial flora, Swamp Cottonwood (Populus heterophylla), and/or are the result of taxonomic
splits to existing species.
Species Code
For data entry in the field it is more efficient to write down (or enter) an abbreviated code, rather
than writing out the entire species name. Therefore an abbreviated code has been developed
that is unique for each species, subspecies and variety listed in this publication.
A seven digit code has been assembled by using the first four characters of the genus name
followed by the first 3 characters of the species name. Therefore, White Trillium (Trillium
grandiflorum) has the 7 digit code of TRILGRA. If there is a subspecies or variety ranking for a
species, then the first two characters are used from the species name, and the third character is
the first letter of the subspecies or varietal epithet. Enchanter’s Nightshade (Circaea lutetiana
ssp. canadensis) has the code CIRCLUC.
In situations where the 7 digit codes for two separate species are the same, then another
character is used for the seventh digit of the code. For example, Water Arum (Calla palustris) and
Common Water Starwort (Callitriche palustris) would both produce the same seven character
code. In this case the code CALLPLS is used for Water Arum, and CALLPLU is used for the
Common Water Starwort. Here are some additional examples;
ii