A guide to nonnative invasive plants inventoried in the north by ...

Cynanchum louiseae
(Syn.: Vincetoxicum nigrum)
Black swallow-wort CYLO11
Louise’s swallow-wort
Form: Scrambling or climbing vine up to 6½ ft (2 m) long.
Stems mostly very slender.
Leaves: Opposite, narrowly to broadly ovate; apex longtapering
or acute.
Flowers/fruit: Few-flowered clusters axillary to the leaves;
flowers small, 5-petaled, star-shaped; corolla purple to
purplish-black. Milkweed-like fruits 1½-3 in. (4-7 cm) long
and slender, with pubescent seeds.
Habitat: Moist, sunny places including woods.
Other distinguishing features/notes: Also known as
Vincetoxicum nigrum.
Similar species: European or pale swallow-wort
(Cynanchum rossicum) has creamy pink to reddish brown
flowers. Its twining habit and opposite, smooth leaves with
somewhat shiny or reflective quality distinguish Cynanchum
louiseae from other native and introduced species in the
northeastern quarter of the U.S. and adjacent Canada.
Notes