Non-native invasive
plants and weeds are a great concern in High Park. These plants
and weeds threaten the biodiversity of the Oak Savannah Ecosystem
because they out-compete the native plant species. The reason for
this is many non-native plant species and weeds spread rapidly,
they thrive in disturbed soil and non-native plants have no predators.
Some species of non-native plants that are very invasive in High
Park are Himalayan Balsam, Garlic Mustard, Dog-Strangling Vine
and Common Buckthorn. To learn more about invasive non-native plants
and their management in High Park refer to the High Park Woodland & Savannah
Management Plan. Below are a few weeds that need to be managed
by the VSP in the park.
*Horseweed
(Erigeron canadensis)
Otherwise known as Canada Fleabane this invasive native weed is
from the Composite or Daisy Family (Compositae). It has numerous
linear lance-shaped leaves and numerous flower stalks springing
from the upper leaf axils. The stems are bristly and the flowers
are small (1/8-1/4”long) and greenish in colour with short
white rays. A single-seeded fruit known as ans achene is produced
by each floret. The plant grows from 3 inches to 7 feet and is
very common in fields, roadsides and anywhere where there is bare
soil. It’s crushed leaves and stem have a carrot scent. The
leaves of horseweed may cause skin irritations for some people.
This weed is present from July through to November.
Photo by Lisa Kemp
*Newcomb,
Lawrence. (1997). Newcomb’s Wild Flower Guide. Little,
Brown & Company, Canada.
Roger Tory
Peterson and Margaret McKenny, 1986. Peterson Field Guides Wildflowers
North East/North Central North America. Houghton
Mifflin, Boston.
France Royer
and Richard Dickson, 1999. Weeds of Canada and the Northern United
States. The University of Alberta Press.
*Purslane
(Portulaca oleracea)
This non-native weed is from the Purslane Family (Portulacaceae)
and also goes by the name Pusley. It has rosettes of fleshy, paddle-shaped
leaves, each with a small (1/4” wide) yellow flower. It is
grows low to the ground in large circular mats up to 1.2m across
and it is succulent with short leaves less than an inch long scattered
along its brownish stems. The flowers only open for a few hours
in the morning sun and there are usually five petals but sometimes
four or six. Its seeds are ovate to triangular, reddish brown to
black and shiny. Each plant is capable of producing 240,000 seeds
which are viable for up to 40 years. It is found in gardens and
bare ground from June to October.
Photo by Lisa Kemp
*Newcomb,
Lawrence. (1997). Newcomb’s Wild Flower Guide. Little,
Brown & Company, Canada.
Roger
Tory Peterson and Margaret McKenny, 1986. Peterson Field Guides
Wildflowers North East/North Central North America. Houghton
Mifflin, Boston.
France
Royer and Richard Dickson, 1999. Weeds of Canada and the Northern
United States. The University of Alberta Press.
*Common
Plantain (Plantago major)
This non-native weed introduced from Europe, was first observed
in Canada in Montreal in 1821. Also known as Whiteman’s-foot,
this weed from the Plantain family grows to a height of 6-18 inches.
It has broad basal leaves and a long tight flower head which is
greenish white. Its leaves are ovate or spade-shaped and prominently
ribbed with troughlike stems. Its seeds are triangular to 4-sided,
brownish black and about 1mm long. It is an abundant weed of roadsides,
lawns and bare areas found throughout June to October.
Photo by Lisa Kemp
*Newcomb,
Lawrence. (1997). Newcomb’s Wild Flower Guide. Little,
Brown & Company, Canada.
Roger
Tory Peterson and Margaret McKenny, 1986. Peterson Field Guides
Wildflowers North East/North Central North America. Houghton
Mifflin, Boston.
France
Royer and Richard Dickson, 1999. Weeds of Canada and the Northern
United States. The University of Alberta Press. 
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