Several species of swallow-worts are herbaceous, perennial vines that invade natural areas in northeastern United States. Pale swallow-wort leaves are opposite, dark green, oval, and shiny with entire margins. Pale swallow-wort flowers occur in clusters and dark purple in color. Fruit are pods, similar to milkweed pods that are slender and split to reveal small seeds with tufts of white hair. The hair allows the seeds to be readily dispersed by seeds. Pale swallow-worts invade a wide variety of habitats including old fields, open woodlands, pastures, roadsides, and floodplains. It can rapidly overgrow native understory vegetation and small shrubs, forming dense mats which smother and kill other vegetation. Swallow-worts are native to Europe and were first introduced in the United States in the late 1800s as ornamentals. <www.invasive.org>
Pale swallow-wort is not known to occur in Indiana.