Reply A native planting ordinance enacted in Somerville is believed to be the first of its kind in any urban environment. (Shutterstock) SOMERVILLE, MA — Somerville has passed a native planting ordinance that establishes minimum requirements for native plants and trees to be planted in city-owned parks, open spaces and streets. The legislation, which applies to new plantings carried out by the city or on behalf of the city, defines native plants and trees as those with origins in North America east of the Mississippi River. It requires that native species constitute 100 percent of all new plantings in any City-owned land on the Community Path, the Green Line Extension corridor and riverfront areas; at least 75 percent of new plantings in city-owned parks; and at least 50 percent of street trees and new plantings in bioswales, plazas, streetscapes, and other City-owned property, subject to certain exemptions.