Tree leaves are not just optimized as vascular transport networks and solar collectors, but also as cantilever structures to handle gravity and wind loads. Furthermore, some leaves are optimized to gather rain and dew moisture, and others to shed moisture, and there are also morphic optimizations against drought and freezing. These higher-order factors are not part of Qinglan's fine analysis of the transport and collector requirements.
Let me stick my neck out as a novice Category Theory student: For the purposes of top-down Leaf Morphology Category Theory, Qinglan's Transport and Solar Collector Categories can be Monoidalized and Braided into a Leaf Morphology Groupoid with the Structural and other Monoidal Function Categories.
Thanks for any correction or suggestion.