'Jalap' resin is the cathartic/laxative...if that's what the tea is about.
Supposed to derive from Mexican word 'xalap'. (Mexican xalap would seem to be pronounced something like a Spaniard would say jalap. Presumably, Anglophones reading the word would misassign the sound for 'j'...and then Anglicize the spelling to all sorts of things like "jollop".)