Trees with needle-like or scaly leaves (conifers)
Trees with flat leaves of varying breadth (broadleaf trees)
Trees with simple leaves, not divided into leaflets
Edges of leaves neither toothed nor lobed
Edges of leaves toothed
Edges usually lobed and toothed (some entire); fruit an acorn
Edges lobed, or toothed and lobed; fruit not an acorn
Trees with compound leaves, divided into leaflets
Leaflets arranged feather-like
Leaflets arranged finger-like