What are the plants to be planted on the roof?

Earlier I have discussed how to plant trees on the roof methodically. Now I shall discuss the kinds of trees we can plant on the roof. Since the roof is different from the normal soil or ground there should be more care to be considered while we plant trees on the roof. Normally, it is better to plant only the flowers and some sorts of vegetables which need little amount of soil,water and fertilizers and trees to be short in nature. We must consider the hazard of storm and strong wind on the roof.

Even though, if we can build structure on the roof permanently only then we can plant been, pumpkin, grapes etc.