On Saturday morning in Dallas, artist Tony Matelli gave a talk at the Nasher Sculpture Center about his decades-long career, during which he and his team of assistants have created sculptural works that are mesmerizing in their realism. Some of his most effective pieces take the form of weeds, playfully sprouting up from the floor of gallery spaces. A few years ago, one of Matelli’s seminude Sleepwalker sculptures ignited a firestorm of controversy when it was installed on the grounds of Wellesley college. Some students started a petition to have it removed, calling the work “a source of apprehension, fear and triggering thoughts regarding sexual assault.”