In 1790, James Torrence lived here as a settler but had never claimed the land. Many years later his son registered a patent for it. The meadow lands (part without trees) was owned by John Shields who applied for a patent to it in 1791.
When William Penn Was given his Charter Rights to the Commonwealth of Pennsylvania which he in turn gave to settlers, he asked each one to set aside one acre of woods for every five cleared, so that sufficient woodland could be maintained in his Commonwealth.
Setting aside acreage of timber was not only in compliance with Penn's request, it was good conservation practice. Wise settlers retained uncut forest land near their cleared acres; should fire or storm destroy their homes, they had replacement timbers close at hand. James Torrence recognized this fact, and what is today the Arboretum's grove of virgin timber was his "insurance" against such hazards.
Mr. and Mrs. A. W. Robertson provided wisdom and foresight when they donated the land for the Arboretum as they too looked to the future and provided the public with a woodland and meadowland; the Arboretum could have been a continuous stream of suburban homed without the "insurance" favored by Torrence and Penn.
Mr. Robertson recognized this grove of trees on his property as virgin timber, existing as it had been when the Indians roamed this land. Robertson became one of the founders of the Western Pennsylvania Conservancy and progressed as a man dedicated to the preservation of the Nation's natural heritage.
In 1950 the Pleasant Hills Arboretum Corporation was formed and 8 acres of virgin oak forest was fived to the Corporation for its perpetual management and preservation, along with a substantial cash contribution to cover initial expenses of opening the grove to the public.
On December 20, 1952, a further gift of another 8 acres adjoining the original tract was made to the Arboretum - 4 acres were meadowland, intended for the planting of additional trees (native to the area as well as rare and unusual specimens.) The other 4 acres already had many trees and wildflowers and some shrubs growing on them.
Me. Charles E. Mowry, an original contributor to the Arboretum and one of the early Board Members, was a modern pioneer of the community whose large farmlands adjoined the Arboretum. Mr. Mowry added many lovely plants and trees to the acreage, and cared for sections of the property until his death in 1966.
A tradition of memorial tree planting began on Arbor Day 1965 by the Class of 1965 of Thomas Jefferson High School as well as by the students of other schools in Pleasant Hills. Contributions from individuals either for plantings or maintenance of the Arboretum have always been welcome.