Dennis's  initial work in New England was as a portrait artist.  He began his formal  training  as an apprentice under Richard  in 1973. He worked  on the portraits  the Secretary of the navy James Webb,  Carnial Mederious and other profile portraits.  In 1988 Morton was honored   by  Govenor John Sunnu  at the New Hampshire State House where twenty-five of his paintings were exhibited  for two weeks. 

Moving to Hawaii in 1991, he continued to receive commissions in portrait painting.  He  painted portriats of three circuit judges,Father Damien for the catholic church in Molikia:  William Waldell the last Buffalo Soldier: John Lydgate and family in  Kauai,   Father Chaminade    and Father Mackey of Chaminade.  He was also fortunate to paint Glen Campbell and family. In 2012 he was commisioned to paint Patty Hastie  George Clooney wife in the movie the Descendants.  The portrait of Patty ended up on the cutting room floor but the director Alex Payne did a follow up called the Real Desendants in which he interviewed John Morgan , the head of Kaaawa valley, along with others  about the Hawaiian Alli and its merging with  the  wealthy foreigners.  Alex sent Cammy Spenser from Fox in Los Angeles to John Morgan office  and she saw  the painting of PuuOhulelule , she decided to show the painting then morffing it into reality  to  start her documentary                                                                                    He has sold paintings to Richard Chamberlain and John Travolta and Glen Campbell.   Some of his landscapes have been sold to wealthy clients on Ohua  and have been in the background of at least six episodes of Hawaii fiveO.  Recently  Magnum PI purchased two large paintings for there Hawaii movie set In the mid 90s he began to aggressively pursue his interest and talents in landscape painting, many of his pieces reflect the area of Windward Oahu and Kauai. Thru  the years he moved back an forth from New England and Hawaii painting many studies and paintings in Plen air.  He refers his style as visual impressionism  which can be explained in Richard Whitneys book  "Painting the visual impression" whereby it is a combination of classical realism and impessionist color notes.           

​In January of 2019 Dennis Restored  the painting for Castle Hospital.