Indian Grove consists of seventy-two ponderosa pines in Great Sand Dunes National Park that were peeled by Indigenous people in the 1800s to get bark for food, medicine, and other uses. First recorded in the 1970s by archaeologist Marilyn Martorano, Indian Grove is one of the two largest clusters of culturally modified trees in Colorado.

Located at an elevation of about 8,400 feet, Indian Grove stands in a narrow valley between the sand dunes and the Sangre de Cristo Mountains. It would have been a favorable location for Native American groups: Medano Creek flows nearby, and Medano Pass lies seven miles northeast, allowing access to Wet Mountain Valley and the eastern plains. The area has about 200 ponderosa pines. Native Americans (probably Utes) passing through the area peeled bark from seventy-two of the trees, producing a total of eighty-eight scars. The trees were peeled over a 100-year period, from about 1816 to the early 1900s, with most of the peelings occurring between 1816 and 1846.

The trees were peeled in order to harvest outer bark, inner bark, and other tree substances such as resin, pitch, and sap. Bark had a variety of uses for Native Americans. Outer bark was a construction material used to make trays, saddles, roofs, and walls. Substances such as resin and pitch served as adhesives and waterproofing agents. Inner bark was pounded and eaten; Utes also used it to thicken soups and make teas. One pound of inner bark contains about 595 calories, 2.7 grams of fat, 4.5 grams of protein, and 138.5 grams of carbohydrates, as well as significant amounts of calcium, magnesium, iron, and zinc.

Because the trees were peeled during a period when Utes faced continual encroachments on their traditional hunting grounds, it is probable that some trees at Indian Grove were peeled as an emergency measure to stave off starvation. Others may have been peeled seasonally by women. Bark is easiest to peel in the spring, when the tree’s annual period of growth weakens the bond between bark and wood. Strips were peeled from an initial horizontal cut, resulting in oval or rectangular scars with one notched corner or straight edge where the peel started. Scars at Indian Grove range from five inches to five feet in width and from two inches to nine feet in length; the average scar is seventeen inches wide and four feet long, which would yield about one pound of inner bark.

Many of the peeled trees at Indian Grove were first documented by Marilyn Martorano in the late 1970s. In 1988 Martorano was involved in another survey that found additional peeled trees at the site, and in 1994 each tree’s location was marked and recorded with precise GPS coordinates. In 2000 the site was listed on the National Register of Historic Places.