Pinus resinosa

Native

Dry. Pure stands or mixed with jack pine, eastern white pine, quaking aspen, or northern pin oak. Sandy soil. Full sun.

40′ to 60′

This is an evergreen, coniferous tree rising on a single trunk from numerous lateral roots with vertical sinkers and often a taproot. It is a hard pine. It is typically found in small groves of trees. In Minnesota mature trees are usually 40′ to 60′ tall and up to 36″ in diameter, though in favorable conditions it can reach over 100′ in height.

Young trees are oval in shape with a cone-shaped crown. Older trees have a narrowly rounded crown. The trunk is straight.

The bark on young trees is reddish to pinkish with loose, brown-gray scales. On mature trees the bark is thick, light reddish-brown, furrowed and cross-checked into broad, flat, irregularly rectangular, scaly plates.

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. Branches near the crown are ascending. Lower and middle branches are horizontally spreading, often drooping with the tips somewhat ascending. Older branches toward the bottom die and fall off.

The twigs are moderately slender, orange to reddish-brown, hairless, shiny, grooved, and ridged. They are not glaucous. They become darker brown and rough and scaly as they age.

The buds are egg-shaped or cone-shaped, ⅝″ to ¾″ long, slightly pointed, and not very resinous. They are covered with loose, overlapping, orangish-brown to reddish-brown scales. The margins of the scales have a fringe of white hairs.

The needle-like leaves are dark green and shiny, with narrow bands of white dots. They are 4″ to 6″ long, slender, straight or slightly twisted, sharp-pointed, and brittle. If bent they will snap cleanly. In cross section they are triangular in shape and have two fibrovascular bundles. The white dots are pores surrounded by 2 glaucous cells, and are evident on all surfaces. Needle edges are finely toothed. Needles are borne in bundles of 2 with a sheath at the base. The sheath is ⅜″ to 1″ long, and does not fall off before the needles. The needles are evergreen, remaining on the tree 4 to 5 years.

Male and female cones are borne on the same tree. Pollen (male) cones are cylindrical, ⅜″ to ¾″ long, and purple. They are borne in clusters on older branches in the lower part of the crown at the base of the the previous year’s shoots. Female cones at the time of pollination are red, spherical, ⅛″ long conelets. They are borne usually in clusters near the tip of the new shoots. On younger trees they are in the middle third of the crown, on older trees they are in the upper third of the crown. Pollination takes place in late May or early June. Male cones shed pollen then wither and fall away.

Fertilization takes place 13 months after pollination. After fertilization the conelets elongate quickly, reaching full size, 1½″ to 2¼″ long, by mid-July. Mature seed cones are light red-brown, woody, egg-shaped, and symmetrical. They are nearly stalkless, usually in pairs, and point outward from the stem. They are covered with spiraling rows of scales. 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), is grayish-brown to tan or greenish-gray, slightly thickened, slightly raised, with a low ridge from side to side. There is a sealing band adjacent to the apophysis where the scales meet when closed. There is a prominent protuberance (umbo) centrally located on the apophysis, on the ridge. There is no prickle on the umbo. The scale tip is pressed closely against the next scale, not free. 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 brown, mottled with black, egg-shaped, 3 ⁄32″ to 3 ⁄16″ long, with a ⅜″ to ⅝″ long, pale brown wing. The wing is loosely attached to the seed (articulate), and is easily pulled away.

Austrian pine (Pinus nigra) needles are flexible, not brittle, and do not snap in two when bent. The seed cones are yellowish brown and have prickles. It does not occur in Minnesota.

The champion red pine in Minnesota is in the Lost 40 SNA, in Itasca County. In 2010 it was measured at 120′ tall and 115″ in circumference (37″ in diameter).

This is Minnestoa’s state tree.