Combustible Lemon Launcher
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(Lemon Tree Planks and Lemon Tree Logs are registered to the OreDictionary)
Lemon Trees spawn randomly in newly generated chunks. There's a config option to disable the spawning (requires restart) and they behave just like normal trees: they decay, drop saplings, can be planted and be used by bone meal.
Lemon Trees come with normal leaves and lemon leaves. Lemon Leaves drop the Lemon Item, which is edible. Lemons are registered to the OreDictionary as