swallowwort

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several vines of the genus Cynanchum having clusters of small white or brownish-purple flowers and slender dehiscent pods.

from The Century Dictionary.

• noun The European herb Cynanchum (Asclepias) Vincetoxicum, or white swallowwort, the plant anciently called asclepias. Also called vincetoxicum (which see) and tame-poison.
• noun Hence, as a book-name, any plant of the genus Asclepias, the milkweed: applied also to the soma-plant, as formerly classed in Asclepias, and to an umbellifer, Elæoselinum (Thapsia) Asclepium, perhaps from its external resemblance to an asclepiad.
• noun The celandine, Chelidonium majus, once fancied to be used by swallows as a sight-restorer. Compare swallow-stone.

from the GNU version of the Collaborative International Dictionary of English.

• noun See celandine.
• noun A poisonous plant (Vincetoxicum officinale) of the Milkweed family, at one time used in medicine; -- also called white swallowwort.
• noun a plant of the genus Stapelia.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of several vines of the genus Cynanchum.
• noun A tetterwort, Chelidonium majus or Sanguinaria canadensis.
• noun Any of various plants of the genus Asclepias.
• noun The plant Euphorbia maculata.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun tropical herb having orange-red flowers followed by pods suggesting a swallow with outspread wings; a weed throughout the tropics
• noun perennial herb with branched woody stock and bright yellow flowers
• noun perennial herb with branched woody stock and bright yellow flowers