Here’s a rhyme I heard as a boy, lost for years, and then rediscovered in my 40s:
Oak logs will warm you well, if they’re old and dry;
Larch logs of pine-woods smell – but the sparks will fly!
Beech logs for Christmas-time; Yew logs heat well!
“Scotch” logs it were a crime for anyone to sell.
Birch logs will burn too fast, Chestnut scarce at all;
Hawthorn logs are good to last if cut in the fall.
Holly logs will burn like wax. You should burn them green.
Elm logs like smoldering flax – no flame to be seen.
Pear logs and apple logs, they will scent the room;
Cherry logs across the dogs smell like flowers in bloom;
But ash logs all smooth and grey – burn them green or old –
Buy up all that come your way; they’re worth their weight in gold.
I also got a fair-sized pile of eucalyptus when my father-in-law had one cut down, but it needed careful handling: at least a couple of years seasoning, but it had to be split green, before the gum sets rock-hard. I have seen a picture of a hydraulic log-splitter that’s come off worse after trying to split a mature eucalyptus log. It also makes quite a bit of resinous waste when it’s burned so it should be mixed in with plenty of other wood so that you don’t get too much gummy soot at once fouling up your flue. If you do all of that, you get quite a lot of heat out of it.