In JBAmb spelled variously לבלב , ליבלב , לילב and even simply ליבב

The usage as the sprout of the palm is almost certainly borrowed from or influenced by Akkadian liblibbu.
The magical usage as the core of the physical heart may be simply a play on lbb; q.v. and see s.v. ṭrpws, ṭrpwsˀ n.m. : "membrane".