One of the best and easiest found bush that can be used in any season.
I usually get a decent handfull of leaves/bark/stems/branches in break them down to fit my pan and put in about a cup of water and simmer for about 10-15 minutes. You might need a wat to strain the material when you pour your tea in the cup. Drink it hot or cold and sweeten to your liking. I usually perfer mine plain.
