What kind of lens hood should I use?

I have a Nikon D3100 that came with an 18-55 mm lens but no hood. The hood that is compatible (according to the nikon website) with this lens is the solid ring hood HB-45, but I much rather want buy the HB-25 or the HB-28 flower lens hood. Is there a difference between the two types or can I go with the flower one instead?

You can go with which ever will fit on your camera. If both do then i don't see any benifiet one over the other. I have a flower lens hood on mine lens it came with the lens but i always leave it on.

I'm curious, why do you want one of the flower lens hoods if Nikon recommends another? There are two parameters of importance with lens hoods: whether it fits the lens and the degree to which it blocks unwanted light without causing lens vignetting at short focal lengths. With this in mind, I always get the hood recommended by the lens manufacturer. I assume that they tested it thoroughly and that it performs the best on the lens in question.