The Collaborative International Dictionary of English v.0.48:
Swallowwort \Swal"low*wort`\, n. (Bot.) (a) See Celandine. (b) A poisonous plant (Vincetoxicum officinale) of the Milkweed family, at one time used in medicine; -- also called white swallowwort. [1913 Webster] African swallowwort, a plant of the genus Stapelia. [1913 Webster]