Asked September 09, 2017, 11:11 AM EDT
Clackamas County Oregon
Thank you for including an image of your lemon tree with your question.
Lemon tree leaves are known to curl upward when the tree
runs short of water.
Lacking a time line of events, my best guess is that the tree ran short of water when the leaves were very new but not yet fully developed and turgid. Thus, the upward curl became permanent. Those leaves won’t unfurl. Even so, it’s important to retain them because they are green and are photosynthesizing on behalf of the tree.