The Collaborative International Dictionary
Ipomoea Orizabensis
Jalap \Jal"ap\, n. [F., fr. Sp. jalapa; -- so called from Jalapa, a town in Mexico, whence it was first obtained.] (Med.) The tubers of the Mexican plant Ipom[oe]a purga (or Exogonium purga) of the family Convolvulaceae, a climber much like the morning-glory. The abstract, extract, and powder, prepared from the tubers, are well known purgative (cathartic) medicines, and are also called jalap. Other species of Ipom[oe]a yield several inferior kinds of jalap, as the Ipom[oe]a Orizabensis, and Ipom[oe]a tuberosa.
False jalap, the root of Mirabilis Jalapa, four-o'clock, or marvel of Peru.