A wide variety of plants have been exploited for the sugar they contain. These may be present in stems or tubers where they function as a food store for the plant. Sugar is also formed in seeds when they germinate, to provide food for the young plant. Seeds are deliberately germinated to make malt.
One of the first sources of sugar to be exploited was honey. This comes indirectly from plants, by courtesy of the bees. Having extracted the sugary nectar from flowers, bees use enzymes in their saliva to split the sucrose into dextrose and fructose. Fructose is the most abundant sugar in honey, which is therefore considerably sweeter than a sucrose syrup of the same concentration. However, because it is an impure and variable food containing other flavourings, subjective assessment of its sweetness varies greatly. Some of the best and most flavourful honeys seem less sweet than plain sucrose.