rose of Sharon
Concise Oxford English Dictionary © 2008 Oxford University Press:
rose of Sharon
▶noun
- 1 a low shrub with dense foliage and large golden-yellow flowers, native to SE Europe and Asia Minor. [Hypericum calycinum.]
- 2 (in biblical use) a flowering plant whose identity is unknown.
– origin from Sharon, a region of fertile coastal plain in present-day Israel.
'rose of Sharon' also found in these Oxford entries:

