What you're seeing is a natural phenomenon and nothing to worry about. That one branch represents a mutation; mutations just happen.

If you like the new branch, you can reproduce it by propagation. Maybe air-layering or cuttings at a certain time of year. I'm not familiar with this plant, though, so you may want to research this further.

Mutations are what plant breeders love to find because the "new" plants can be sold as new cultivars. So you may have something special there. Maureen

THOUGH, it is useful to note, some mutations are brought about by viruses, which CAN spread to plants that won't be so happy.

First, are you talking about a real eucalyptus? I would never describe them as hairy. But real eucalypts have juvenile and adult leaves, quite different in shape and form. If you were handed a sample of each, you would not believe they are from the same plant. They are just about impossible to propagate by cutting ( I have this from a university professor who spends her life working with eucalypts) Even the most high tech tissue culture doesn't work with eucalypts.
So, if it is a real eucalypt, it is just maturing, and the change is normal.

Last year i purchased a eucalyptus lemon tree after a short time it got three lemons on it one the grandchildren picked when it was too small,one fell off in a storm and the last one came off when it was very ripe but unfortunately i was away at the time,now its been months and it still has not started reproducing how often does a eucalptus produce fruit and how can i assist this?

I recently transplanted a one year old lemon eucalyptus from a pot to the ground and this spring my new growth is exactly as described above. Smooth and waxy and unlike anything I remember seeing in the new growth last summer. Does anyone have more information on this?

Shane, we never established what plant is actually being talked about in this thread. Can you show us a photo of your plant so we can start with an accurate id?