Nature of dependent origination, and is Buddhism non-duality?

Is dependent arising meant for us to understand the arising of suffering -- or is it also meant to describe how phenomena in the outside World arise dependent on other conditions (for instance how water and sun causes a flower to grow)? I think Nagarjuna says that dependent origination is not only showing how suffering arises, but also how phenomena in the World arises. He uses a sutra in the Pali Canon where the Buddha said that this World is dominated by a duality of existence and non existence, then he continued, "when one sees the origination and cessation of the World existence and non existence do not occur to one anymore". This seems to confirm what Nagarjuna said: that dependent origination is not only describing how suffering originates, but how phenomena in the World also originate -- isn't that so? --- I have another question also: how would you describe Theravada, Mahayana, Vajryana and Tibetan Buddhism -- are they non dual or not? Please describe to me the logic why you answered the way you did also.