Eucalyptus buds

I've started doing a correspondence course in Horticulture, and I have to identify various plants of my own choice for each lesson. I cleverly found this eucalyptus up at Mt Rogers this morning and brought this sample home to photograph, thinking it would be easy to identify. Not so! It's possibly Eucalyptus mannifera (Brittle Gum) but I'm not sure. I think I'll have to start at the botanical gardens for eucalypti until I'm a bit better educated about them.