Had a quick look in my encyclopedia, it depends on if these are greek gods or roman gods so its a bit confusing. From what I can make out, Jupiter is the oak tree, Pluto the cypress, Apollo was the laurel,Venus was the lime tree because of its heart shaped flowers although the myrtle and rose are also associated with Venus. Juno appears to be the lily or Iris.These are not absolutely definite but it may give you some clues for further research.