Part 12

c. Bark of trunk red-brown; cones maturing in second season, about 2 inches long; cone-scales thickened at the apex, but unarmed. P. resinosa, p. 15.

cc. Bark of trunk gray to nearly black; cones maturing in first season, 2-3 inches long; cone-scales thickened at the apex and topped with a short spine. P. laricio austriaca, p. 11.

+WINTER KEY TO THE SPECIES OF PINUS+

a. Leaves 5 in a cluster; cones 4-10 inches long. P. strobus, p. 7.

aa. Leaves 2 in a cluster; cones less than 4 inches long.

b. Leaves 1-3 inches long.

c. Leaves about 1 inch long, divergent; cones sessile, pointing forward towards the tip of the branch, persistent 10-15 years, opening very unevenly. P. banksiana, p. 9.

cc. Leaves 1-1/2-3 inches long, slightly divergent; cones stout-stalked, pointing away from the tip of the branch, maturing in second season, opening evenly. P. sylvestris, p. 13.

bb. Leaves 3-6 inches long.

c. Bark of trunk red-brown; cones maturing in second season, about 2 inches long; cone-scales thickened at the apex, but unarmed. P. resinosa, p. 15.

cc. Bark of trunk gray to nearly black; cones maturing in first season, 2-3 inches long; cone-scales thickened at the apex and topped with a short spine. P. laricio austriaca, p. 11.

1. Cluster of leaves, × 1. 2. Cross-sections of leaves, enlarged. 3. Partly opened cone, × 3/4. 4. Cone-scale with seeds, × 1.]

+PINACEAE+

+White Pine+

Pinus strobus L.

HABIT.--A large tree 60-80 feet high, with a trunk diameter of 2-4 feet; forming a wide, pyramidal crown. Formerly trees 100-150 feet in height and 5-7 feet in trunk diameter were not exceptional.

LEAVES.--In clusters of five; 3-5 inches long; slender, straight, needle-shaped, 3-sided, mucronate; pale blue-green. Persistent about 2 years.

FLOWERS.--June; monoecious; the staminate oval, light brown, about 1/3 inch long, surrounded by 6-8 involucral bracts; the pistillate cylindrical, about 1/4 inch long, pinkish purple, long-stalked.

FRUIT.--Autumn of second season, falling during the winter and succeeding spring; pendent, short-stalked, narrow-cylindrical, often curved, greenish cones, 4-10 inches long; scales rather loose, slightly thickened at the apex; seeds red-brown, 1/4 inch long, with wings 1 inch long.

WINTER-BUDS.--Oblong-ovoid, sharp-pointed, yellow-brown, 1/4-1/2 inch long.

BARK.--Twigs at first rusty-tomentose, later smooth and light brown, finally thin, smooth, greenish; thick, dark gray on the trunk, shallowly fissured into broad, scaly ridges.

WOOD.--Light, soft, weak, compact, straight-grained, easily worked, light brown, with thin, whitish sapwood.

DISTRIBUTION.--Upper Peninsula and Lower Peninsula north of Allegan, Eaton and St. Clair Counties. Often planted as an ornamental tree farther south.

HABITAT.--Prefers a light, fertile loam; sandy soils of granite origin.

NOTES.--Rapid of growth. Small seedlings easily transplanted. Formerly very abundant, but rapidly nearing extinction through destructive lumbering.

1. Cluster of leaves, × 1. 2. Cross-section of leaf, enlarged. 3. Branchlet with unopened cone, × 1. 4. Branchlet with opened cone, × 1. 5. Cone-scale with seeds, × 1.]

+PINACEAE+

+Jack Pine. Scrub Pine+