Dan Ladd is a Northampton, Massachusetts based American artist who works with trees and gourds. He began experimenting with glass, china, and metal inclusions in trees in 1977 in Vermont and started planting trees for Extreme Nature in 1978.[50] He became inspired by inosculation he noticed in nature and by the growth of tree trunks around man-made objects such as fences and idle farm equipment.[50] He shapes and grafts trees, including their fruits and their roots, into architectural and geometric forms.[50] Ladd calls human-initiated inosculation 'pleaching' and calls his own work 'tree sculpture'.[50] Ladd binds a variety of objects to trees, for live wood to grow around and be incorporated, including teacups, bicycle wheels, headstones, steel spheres, water piping, and electrical conduit.[50] He guides roots into shapes, such as stairs, using above-ground wooden and concrete forms and even shapes woody, hard-shelled Lagenaria gourds by allowing them to grow into detailed molds.[51][52] A current project at the DeCordova and Dana Museum and Sculpture Park in Lincoln, Massachusetts incorporates eleven American Liberty Elm trees grafted next to each other to form a long hillside stair banister. Another of his installations, Three Arches, consists of three pairs of 14-foot sycamore trees, which he grafted into arches to frame different city views, at Frank Curto Park in Pittsburgh.[4][53]