The leaflets of compound leaves also display circinate vernation . However, size is not the chief characteristic of megaphylls. A Megaphyll is a leaf which contains more than one vein and its leaf trace is associated with a leaf gap in the stele. A leaf gap occurs when the departure of a leaf trace from the stele results in the development of parenchyma rather than vascular tissues in the stele, just above the leaf trace. This gives the stele a dissected appearance like the dictyostele .
Some ferns have very simple leaf organization with little mesophyll differentiation.
Others have a complex anatomy which rivals the structural specialization of angiosperm leaves.