Eastern White Pine Growing

The eastern white pine (Pinus strobus) is not only Maine's state tree, but its cone and tassel are our state flower as well. Right now in the pine tree state, the eastern white pine is beginning to show signs of growth. The fresh looking shoots coming from the terminal buds of the trees are easily visible. Depending on conditions, some trees can add two feet or more of height in a single growing season.

A new main stem and branches grow quickly from a young eastern white pine on T.A. grounds.

While outside with my classes, we often estimate the age of white pine trees by counting the growth sections along the trunk. Each location that a group of branches meet at the trunk represents the end of a growing year. Eastern white pine is a versatile species and is evolved to spend years in the shaded understory where it may only grow an inch or two a season. Once a competitor nearby falls and sunlight is let it in, the tree can add height quickly. There are trees growing in shady areas along the eastern trail that are shorter than the students but twice their age.

Some of the larger pines along the Eastern Trail are truly ancient. These specimens have the classic tall and straight appearance. They most likely sprouted shortly after Thornton Academy's creation in the early 1800's.

The white pine weevil (Pissodes strobi) is a native insect that many people have never seen but has a direct impact on the health and shape of the eastern white pine in our area. This insect's larvae burrow into the new growth on pine trees causing the terminal bud to wither and die. Each time this happens, the resilient white pine selects a new shoot to become the "leader" and a new main trunk is born. Killing the terminal bud year after year results in eastern white pine that tend to grow out rather than up. Trees that grow in the warmth of direct sunlight are most susceptible to predation from the weevils. Most of the eastern white pine growing in the sunny median along I-95 are effected by white pine weevil and have taken on the classic short/round shape. These trees are not considered as good looking and are worth far less to the lumber industry. Trees that grow to heights of 20 or so feet in the cool understory before taking off in the sunlight tend to end up with the classic tall pine shape.

This eastern white pine has grown for decades in direct sunlight and is a good example of what years of white pine weevil damage will do. It has multiple trunks and has grown larger around than it is tall.