Red Maple
Acer rubrum

Location in Ontario

Red Maple grows throughout the Deciduous Forest Region and northward. It likes moist soil and swamps.

A blush of red in early spring, Red Maples in Norfolk County

Genus Acer
Maple trees have simple, lobed leaves that are opposite and decussate (successive pairs are 90 degrees to each other). Check this link for more about decussate leaf arrangement:

Maples are known for their beautiful fall colours. Maples are monoecious with male (pollen) flowers and female (seed) flowers on the same tree, although some species are solely male or female. Seeds are in double-winged samaras, or keys. Sugar Maple, Black Maple, Red Maple, Silver Maple and the hybrid Freeman's Maple all grow in Ontario.

TREE FACT: Maple trees are divided into "hard" maples (Sugar and Black) and "soft" maples (Silver, Red and Freeman's).

In the Landscape
Red Maple is a medium-sized tree that grows up to 25 metres and can live up to 150 years of age. It is an attractive tree with bright red flowers in early spring and deep red foliage in the fall.

Red Maple, University of Guelph Arboretum

Red Maple leaves have indentations are shallow and the edges have sharp teeth. The leaves turn deep gold or brilliant red in the fall.
The bark is grayish-brown with scaly ridges.
Red Maple is polygamo-monoecious with male (pollen) flowers and female (seed) flowers on the same tree, although some trees have entirely male flowers and others entirely female flowers. Flowers appear in very early spring, before the leaves. Red Maple is one of the earliest flowering trees. Red Maple produces fruit after about 4 years of growth, with good seed crops yearly.  Pollination is by wind.
A single Maple seed is contained in a key; a doubly-winged samara. Maple keys twirl to the ground, dispersed by wind and water. Red Maple keys drop in the spring.
Here is an outstanding video showing the flowers, keys and leaves of Red Maple.

Red Maple has soft wood, and is sold collectively with Silver Maple as "Soft" Maple.
Specific gravity: 0.54
Janka Hardness: 950 lb

Wood Comparison Chart

Red Maple, St. Williams Nursery and Ecology Centre

Link to United States Forest Service Silvics Manual for Red Maple.