Funnily enough, the pot of petunias is part of a "brick joke" in one of the later books, where it is revealed to have been part of a reincarnation-line of a single being, which was killed by Arthur Dent every time it lived, either directly or indirectly. (Hence the 'Oh no, not again')

Douglas Adams had a way of thinking which made him right about quite a lot of future discoveries/technologies, even though most of his predictions were meant as hyperbole...