Meander through the flower-filled Boston Public Garden, then hop on a Swan Boat. Savor the sweet smell of lilacs on May 9th, Lilac Sunday, at Boston’s Arnold Arboretum. Peruse more than 1,000 native plant species, many rare and endangered, at Garden in the Woods in Framingham. Discover the Secret Garden and its fragrant perennials at the Tower Hill Botanic Garden, Boylston. At the Mount Estate & Gardens in Lenox, admire Edith Wharton’s formal Italianate walled garden. In Shelburne Falls, stroll the Bridge of Flowers, an old trolley bridge, now a riot of color in spring.