oleander (n.)

"rose bay," a poisonous evergreen Mediterranean shrub, late 14c., oleaster, from Medieval Latin oleander, a word of uncertain origin, probably altered (by influence of Latin olea "olive tree") from Late Latin lorandrum, from Latin rhododendron (see rhododendron), which was itself altered by influence of Latin laurea "laurel," on resemblance of leaves. This round-about etymology is supported by the French word for it, laurier rose.