Why do bog plants (cranberries, rosemary) that live in conditions of high humidity have a number of characteristics

Why do bog plants (cranberries, rosemary) that live in conditions of high humidity have a number of characteristics characteristic of arid plants (pubescence, wax coating, small leathery leaves)?

1) Swamp water is cold,
2) poorly absorbed by the roots,
3) there is a need to reduce the evaporation of water.

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