Australian Flora and Fauna: Plants of an Arid Land

This is a transverse section of a leaf of Hakea sericea. You can see that there is a central pith surrounded by palisade mesophyll. The location of the mesophyll indicates that they intercept light for photosynthesis from any direction. External to the mesophyll are further layers.

Not all members of the genus Hakea have needle-shaped leaves. The defining characteristics of the genus are its flower and fruit morphology. Leaf shape is not a good indicator of relatedness of plants as it often reflects a species' growing conditions.