IMAGE Australian Beefwood (Casuarina cunninghamiana)
Cross-section of a stem and seven small leaves (microphylls)
Under an Ultraviolet [UV] lamp, things fluoresce in different ways. They don’t look the same color as under daylight. So, ultraviolet light is used ‒ here, under a microscope ‒ to reveal features and differences not seen in visible light.
When examined with the unaided eye, the specimen above appeared to have needles (which it is not supposed to).
Investigating with a UV microscope revealed that instead of a single needle this is a stem with seven small leaves. Not everything is as it appears to our eye.
- The red fluorescence is from chlorophyll in the very small pentagon shaped leaves.
- The blue fluorescence is from secondary metabolites in the vascular (central) and epidermal (outer) tissue.
IMAGE: Gregory Johnson and ASU - Ask A Biologist