I've seen many of these things growing in the water in my greenhouse ponds. Certainly hoya and gingers. Dracaena are famous for growing in water (e.g. lucky bamboo). This spring I found an aloe that had broken off as a pup, landed on an aquatic plant, and rooted into the water. If I toss fig cuttings in the water with part of it sticking out, they will grow there indefinitely with the roots floating in the water (I've gone as long as 12 months before removing the heavily rooted trees).
