This article is reprinted with permission from the Toronto Field Naturalist’s May 2016 Newsletter. Article and photos by Peter Money. Enjoy. It is a good time to find geraniums right now.
The Geraniaceae (geranium family) consists of five or six genera and about 800 species most commonly found in temperate regions. The genus Pelargonium includes species used as ornamental houseplants and as summer bedding plants. Plants so used in Toronto belong to this genus, not to genus Geranium, although commonly called geraniums.
The TFN’s Vascular Plants of Metropolitan Toronto (2nd ed., 1994) listed three Geranium species native to Toronto and three introduced species. The native species are Geranium maculatum, G. bicknellii, and G. carolinianum. One introduced species, G. robertianum, common in wild areas of Toronto, is shown here for comparison.
G. maculatum (wild geranium) is common in Toronto, occurring in forests and meadows from Etobicoke to the Rouge, in High Park and on the Scarborough Bluffs. It blooms at any time from late April to early June. Plants grow up to 70 cm tall and have flowers about 30 mm wide, in terminal few-flowered clusters. The ROM Field Guide to Wildflowers of Ontario (2004) reported its Ontario range from the Lake Simcoe-Rideau ecoregion to the U.S. border and the southernmost ecoregions adjacent to the Manitoba border. The U.S. Dept of Agriculture database shows its range from Manitoba to Quebec and in most of the eastern half of the U.S.
The other two native geraniums, G. bicknellii (Bicknell’s geranium) and G. carolinianum (Carolina geranium) are locally rare, only reported at Wilket Creek (Don). The former is illustrated with a photo from Beausoleil Island. Its summer blooming flowers are 10 to 15 mm across with slightly notched petals. Its leaves are palmately lobed. Its very wide distribution includes all of Canada except Nunavut, and most of the north and central U.S.
In comparison, the introduced species, G. robertianum (herb-robert) has unnotched petals and palmately compound leaves.
Enjoy the common species and, perhaps, try to find the two locally rare species. My Toronto searches for these have not been successful.