1540s, "to plant in" (abstractly, of ideas, emotions, etc.), from French implanter "to insert, engraft" (alongside Old French emplanter "to plant"), literally "plant in," from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + planter "to plant" (see plant (n.)). Meaning "surgically implant (something) in the body" is from 1886, originally of teeth. Implanted is attested earlier, from early 15c., probably based on Medieval Latin implantus. Related: Implanting.
mid-15c., from Late Latin transplantare "plant again in a different place," from Latin trans "across, beyond" (see trans-) + plantare "to plant" (see plant (n.)). Extended to people (1550s) and then to organs or tissue (1786). Related: Transplanted; transplanting. An earlier verb was overplaunten "to transplant" (a tree), late 14c.
"a plant," Old English wyrt "root, herb, vegetable, plant, spice," from Proto-Germanic *wurtiz (source also of Old Saxon wurt, Old Norse, Danish urt, Old High German wurz "plant, herb," German Wurz, Gothic waurts, Old Norse rot "root"), from PIE root *wrād- "branch, root." St. John's wort attested from 15c.