Rose of Sharon
Few Bible plants are as well known as the rose of Sharon. But it is also well known that the precise identity is uncertain. It is, however, definitely not a rose and is only mentioned in this verse.
The book of Song of Songs is interesting not only for the many plants which it includes but for the scope of geography in such a short book. Gilead in the east, Mount Hermon, Lebanon and other places in the north are mentioned but also a city in the hill country (Tirzah), parts of Jerusalem, Ein Gedi on the shores of the Dead Sea in the south, and Sharon. Sharon is the fertile coastal plain, fifty miles long and between nine and ten miles wide which parallels the Mediterranean in the northern half of Israel.
In addition to the rose (Rosa sp.), tulip and narcissus have been suggested as the rose of Sharon. However, assuming that the fertile plain of Sharon was an area of agricultural activity in Bible days and that the weed flora of modern grain fields (in traditional cultivation, not large scale mechanization) is similar to that of Bible times, I believe that Gladiolus italicus and G. atroviolaceus both could Rose of Sharon.
Both species occur in wheat fields that have been shallowly cultivated, either by animals or by hand. They flower in the spring and then die back to the corm. Asexual reproduction from the corm by the disturbance of cultivation probably spreads the plants.