Tundra is ... treeless. Genera that are trees or large shrubs further
south (e.g. Betula, Rhododendron, Salix, below) are represented here
by species of much smaller stature. In Ontario, tundra occurs along the coasts
of Hudson Bay and James Bay. Much of the herbaceous vegetation consists of sedges
and grasses. The weight of the most recent continental
ice sheet depressed the land here so that, when the glacier melted, seawater
flooded in to create the Tyrell Sea. Since that time the land has been slowly
rising, so as to produce the modern shoreline of Hudson and James Bays. Even now isostatic
rebound is continuing, as can be seen by the succession of beach ridges that
parallels the coastline in the image below.
La Perouse Bay, near Churchill MN. Left: willow thicket with polar bear; photo E. R. Chang - © E. R. Chang 1998. Right: sedge meadow; photo T. Handa - © T. Handa 1998.
develops in the sheltered depressions between the beach ridges at Cape Henrietta
Maria, where Hudson Bay and James Bay meet (Riley 2003).
John Riley, photographer; © NRC 2003.
Salix arctica; photo D. Davidson - © D. Davidson 1998.
Salix reticulata; photo D. Davidson - © D. Davidson 1998.
Betula glandulosa; photo E. R. Chang - © E. R. Chang 1998.
Polygonum viviparum; photo E. R. Chang - © E. R. Chang 1998.
Rhododendron lapponicum; photo E. R. Chang - © E. R. Chang 1998.
The photograph of Cape Henrietta Maria appears in Flora of the Hudson Bay Lowland and its postglacial origin (2003) and is used with permission here. It was taken by John L. Riley and is © the National Research Council of Canada 2003.
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