As if there weren’t enough fun summer reasons to visit Jamaica Plain, there is always the Arnold Arboretum. Truth be told, the personality of this second link in Frederick Law Olmstead’s, “Emerald Necklace,” chain of green spaces distinctly changes with each season but summer is when a high percentage of the more than 15,000 individual plants are in bloom. Founded in 1872 when the President and Fellows of Harvard College became trustees of a portion of the estate of James Arnold, the Arboretum is still governed by Harvard under the terms of a one thousand year lease from the city of Boston. The two hundred and sixty-five acres (with altitudes ranging from 46 feet in the meadow to 240 feet at the top of Peters Hill) are open free of charge to the public from sunrise to sunset 365 days of the year. Visit www.arboretum.harvard.edu to plan your trip, print out maps or lock into a smart phone application to help decipher the varied foliage.