Of course I can't be sure, but the trees were probably Australian Pines, Causarina equisetifolia. This tree has moved into many tropical locations leaving ecological damage in its wake. As with many invasive species, Australian Pines were brought in to prevent erosion due to their rapid growth. They are very beautiful trees with elegant, sweeping branches adorned with hanging needles that impart a veil-like quality. Especially successful in dune areas, they displace naturally occurring native erosion-preventing vegetation, one of the cruel ironies when dealing with exotic invasives.
Allow me to get on my soap box for a moment. Extremely rapid-growing exotic plants should send up the red flag for all of us when considering their use in our gardens or anywhere for that matter (not that you were considering this plant for your garden, but this is often the case). The lesson learned from exotics that were brought in because of their attractive appearance and rapid growth is to be vigilant in spotting them and to help in their eradication. If this is of interest to you, Minnesota has its fair share of exotics and interested citizens can work with the Minnesota Department of Natural Resources in managing the spread of invasive plants. You are lucky to have such a vibrant program in your state and perhaps you will get involved. I realize that your question addressed a tree you saw on a trip, but your question presented an opportunity to discuss this plant that has caused such widespread destruction in tropical spheres.
If by any chance this was not the tree you saw in Punta Cana then please get back with me and we can look into it further. Thanks for the question, and for Florida visitors to eNature, be sure to check out the links below.