The actual identity of biblical plants is an ongoing (and sometimes hotly contested) debate. The current forerunners for the
Rose of
Sharon identity are:
Lilium candidum, the Casablanca or
Madonna Lily (pictured in the florist link supplied by Pashute) This theory is supported by the research of Israeli botanist
Michael Zohary.
Tulipa montana (altenately Tulipa wilsoniana) and/or Tulipa sharonensis, wild tulips that grow on the coastal plain of
Sharon.
Narcissus odorus, Sweet-scented Narcissus/Jonquil
And there are several more contenders. Simply put: botanists, the Biblical translators weren't.