The region of the leaf lamina proximal to the stem and usually connected to it by means of a petiole. [source: GR:Chih-Wei_Tung]
Comment
If you are annotating to this term, please add an additional annotation to vascular leaf (PO:0009025) or non-vascular leaf (PO:0025075), depending on the species. All annotations for angiosperms, gymnosperms, and pteridophytes should go to vascular leaf and all annotations for bryophytes should go to non-vascular leaf.