Complex sentence: I don't want to make a political statement, in reference to what he refers to as a "rather intolerant horticultural chauvinism" (towards Australian plants) exhibited by Australian garden designers.
Split into simpler sentences: I don't want to make a political statement. The latter being a reference to what he refers to as a "rather intolerant horticultural chauvinism" (towards Australian plants) exhibited by Australian garden designers.