Yup, I agree, floral pics filled with water, but you need to be careful because too many of them inserted into the cake and the surface may crack open. I've heard that some surround the stem with a piece of plastic straw and some take it even further by wrapping the stem in moist paper towel strips then insert the stem in a larger straw. There are some very tiny floral pics on the market now which are ideal. For the top tier I usually have the florist make up a display inserted into a moist floral foam container which is secured to a green plastic disk. The plastic disk sits on the icing and the flowers don't touch the cake.