Pinus strobus

Native

Deciduous forests, stream banks, river banks. Sandy or gravelly areas with moist soil. Full sun.

40′ to 70′

This is an evergreen, coniferous tree rising on a single trunk from 3 to 5 moderately deep lateral roots. It is the only Soft Pine native to Minnesota. It is usually found as individual trees or small stands in deciduous forests. In Minnesota mature trees are usually 40′ to 70′ tall and up to 42″ in diameter, though giant individuals can reach over 100′ in height. It is the tallest conifer in northeastern North America.

Young trees are pyramidal in shape with a cone-shaped crown. Older trees have an irregular, rounded or flattened crown. The trunk is straight.

The bark on young trees is thin, smooth, and grayish green. On mature trees the bark is gray-brown tinged with purple and 1″ to 2″ thick. It is deeply furrowed into long, broad, connected, irregularly rectangular plates separated by deep, darker furrows.

The branches are stout, horizontal, and whorled, each whorl representing one year of growth. The tree’s age can be determined by counting the number of whorls from the bottom up.

The twigs are green and hairless or hairy in the first year. They become orange-brown and hairless in the second year.

The buds are slender, egg-shaped, ⅛″ to ⅝″ long, and sharp-pointed. They are covered with overlapping reddish-brown scales.

The needle-like leaves are bluish-green with 3 or more lines of white dots. They are 2″ to 5″ long, slender, straight, soft, and flexible. In cross section they are triangular in shape and have one fibrovascular bundle. The white dots are pores surrounded by 2 glaucous cells, and are evident only on the upper surface. Needle edges are finely toothed. They are borne in bundles of 5 with a sheath at the base. The sheath is ⅜″ to ⅝″ long and falls off after the first year. The needles are evergreen, and can remain on the tree for up to 4 years, but usually turn yellow and fall after 2 years.

Male and female cones are borne on the same tree. Pollen (male) cones are cylindrical, ⅜″ to ⅝″ long, and yellow or light brown. They are borne in clusters on older branches in the lower part of the crown at the base of the new shoots. They shed pollen in the late spring then wither and fall away. Female cones at the time of pollination are green, 3 ⁄16″ to 1½″ long conelets. They are borne in clusters on newer branches in the upper part of the crown near the tip of the new shoots. They mature after 2 years.

Mature seed cones are yellow-green to light brown, 3″ to 8″ long, cylindrical, slightly curved, and flexible. They hang downward on a slender, ¾″ to 1⅛″ long stalk. They are covered with usually 5 spiraling rows of 10 to 16 scales each. The scales at the tip and the base are small and are not fertile.

Mature seed cone scales are thin and rounded at the tip. The tip of the scale, that portion that is exposed when the cone is closed (apophysis), has purple or gray tints, is not shiny, and is not much thicker than the adjacent part. There is no sealing band adjacent to the apophysis where the scales meet when closed. There is a prominent protuberance (umbo) terminating the scale tip. There is no prickle on the umbo. The scale tip is free, not pressed closely against the next scale. At maturity the scales bend backward, releasing the seeds. Soon after that the cones fall to the ground.

There are 2 seeds in each fertile scale. The seeds are reddish-brown, mottled with black, 3 ⁄16″ to ¼″ long, with a ¾″ to 1″ long, pale brown wing. The wing is fused to the seed (adnate).

This is the only pine in Minnesota with long needles in clusters of 5.

The champion eastern white pine in Minnesota is near the entrance of Forestville State Park in Fillmore County. In 2009 it was measured at 103′ tall and 214″ in circumference (68″ in diameter).