Sandbanks Draft Veg Mgmt Plan - Ontario Parks

APPENDIX E – Invasive Species Information Sheets
Dog-strangling Vine Vincetoxicum rossicum (Kleo.) Barb. & V. nigrum (L.)
Moench.
Milkweed Family Asclepiadaceae
Alternate Common Name
Black Swallow-wort and Pale Swallow-wort
Distribution
Pale Swallow-wort (V. rossicum) is more prevalent in Ontario than Black Swallow-wort (V.
nigrum). This species can be found from Hamilton to Cornwall and north to Lake Simcoe
and Ottawa (Kubisz, 1992). Dog-strangling Vines commonly occur in old fields, disturbed
corridors, and forest edges (Sheeley, 1996). Another Vincetoxicum species, V. hirundinaria
Medik., has been located in a few locations in the Niagara region, but there have been no
records of this species in the past few decades. Black Swallow-wort is native to the
Mediterranean region, and Pale Swallow-wort is native to the Ukraine and southern Russia
(Sheely, 1996).
Dog-strangling Vine is currently found in Presqu’ile, Sandbanks and Darlington Provincial
Parks. The abundance and distribution at Sandbanks is unknown. The distribution at
Presqu’ile is patchy and confined to high use areas, although it is starting to show up in
woodland areas. The Darlington population is spreading, and is also found growing in a
conifer plantation.
Biology and Ecology
General Identification: Vincetoxicum spp. are herbaceous perennial vines, that grow either
erect, or twining on supporting vegetation. Vincetoxicum can grow up to two metres in
height, depending on the habitat. Subterranean buds on the root crown are present. V.
nigrum has rhizomes, but it is yet to be determined if rhizomes are present on V. rossicum.
Leaves: The leaves are opposite, 5-10 cm long, hairless and smooth/shiny, oblong to ovate,
narrowing to a point at the tip, rounded to subcordate at the base with short petioles, and the
margins are entire to wavy.
Flowers: The flowers are 5-9 mm wide, arising from the leaf axil, with 3-10 flowers per
cluster. Black Swallow-wort flowers are purple-black, and Pale Swallow-wort flowers are
pale to dark maroon, purple or pinkish. Both species have 5 fleshy petals
Fruits: The pods are typical of the milkweed family. Pods are 4-7 cm long and slender,
persisting on the vine after splitting lengthwise to release many tufted windborne seeds.
Seeds are released in late summer to fall on windy, dry days.
Similar species: May be confused with other milkweeds when the plants are either young
or stunted.
Habitat: Dog-strangling Vine is associated with disturbed areas, such as hydro corridors, old
fields, quarries, nurseries and Christmas tree farms. Dog-strangling Vine occupies a wide
ecological niche, and does well in full sun or partial shade, and in moist or dry soils. These
plants can also invade deeply shaded areas, although seed production is reduced in this
habitat type. Natural areas that have some type of disturbance regime may also be invaded.
Alvar communities are often invaded due to the extreme hydrologic regime. Although Dog-
Sandbanks Vegetation Management Plan A-16
Ontario Parks, SE Zone
2009