Red Pine grows into a large tree, upwards of 100 feet high and 30 to 40 inches in diameter, usually with a straight trunk. Branches form an open rounded head on older trees after the lower branches fall away. Young trees will be a pyramidal shape. Upper branches are usually ascending while lower branches may be descending. One whorl of branches is produced annually from the leading shoot.
The bark on mature trees is divided into cross-checked reddish-brown plates, yielding the common name. Bark on smaller branches will be gray and flaky. A resinous pitch is frequently encountered on the bark.
Twigs are orange-brown in color, maturing to darker brown, with narrow resinous buds of the same color. Bud scales have fringed margins.
Leaves: The needles occur in clusters of two, are yellow-green to dark green and 4 to 6 inches long with narrow pore bands (stomata). Fresh needles will snap cleanly in two when bent. Only the Austrian Pine (P. nigra) has long needles in clusters of two, but that tree is not native to Minnesota and the needles do not break cleanly. The interior section of the branches will be devoid of needles - they cluster at the outer tips. Needles last for up to 6 years before turning brown and falling off.
Flowers: The tree is monoecious, that is, male and female flowers are separate and in this species they develop on separate branches. Male flowers are purplish-red, ovoid in shape, 1/2 to 3/4 inches long and appear in clusters at the branch tips of the current years growth. These elongate when the pollen is ready for release and are yellow with pollen. Female flowers develop in the middle or upper branches and are a round short cone of reddish-brown color. The almost stalkless mature cone is short and stubby, egg shaped, about 2 inches long, shiny light brown in color turning gray with age. They are green initially.
Seeds: Pine cones are composed of scales which in this species are thin but slightly thickened at the tip and slightly concave (keeled) and not prickled. Two ovoid winged seeds develop for each scale. The cones are fertilized via wind pollination and self pollination. Cones mature in late summer of the second year and disperse seed by wind in the fall. Cones are similar to P. nigra, Austrian Pine. Trees produce male cones about 9 years of age and female cones around 5 years. Seeds remain viable for up to 3 years. Green cones and old cones will frequently be sticky with a resinous pitch.
Habitat: Red pine will grow best in well drained sandy soil - the tree is somewhat shade tolerant but grows best with at least 6 hours of sun; it is very cold tolerant. The root system is deep and wide spreading, creating a sturdy long-lived tree that is the dominant species where it occurs. The alternate common name of Norway Pine is thought to be from a confusion of the early English settlers with the Norway Spruce. Some thought it was named for Norway Maine where the tree occurs, but that town was only founded in 1797 and the name was in prior use.
Names: The genus Pinus is the Latin name for the pine tree. The species resinosa means resinous referring to the sticky sap of the tree and the sticky green cones. The author name for the plant classification, ‘Aiton.’ is for William Aiton (1731-1793, Scottish botanist who succeeded Phillip Miller as superintendent of the Chelsea Physic Garden and then became director of Kew Gardens, where he published Hortus Kewensis, the Garden’s catalogue of plants. In older literature this species was sometimes referred to as Pinus rubra.
Above: A younger Red Pine showing the pyramidal shape of a younger tree. Drawing from North American Sylva by F. Michaux and T. Nuttall.
Below: 1st photo - The pollen cones of the male flowers develop at the ends of new twigs. 2nd photo - After pollination, they fade and new needles grow.
Below: 1st photo - Male flowers shedding pollen become yellowish. 2nd photo - Female flower are short reddish cones. 3rd photo - Bark of mature trees separates in plates exposing a reddish interior.
The female flowers develop into the seed bearing cones and mature in the second year. Above: A new cone of the season in the green stage.
Below: 1st photo - maturing cones of the prior years growth in late summer. 2nd photo - Old cone from a prior year which remains on the tree covered in resin.
Below: Red Pine is the only native pine in Minnesota with two long (to 6+ inches) needles in a bundle.
Notes: Red Pine is not indigenous to the Garden area nor to Hennepin County. Eloise Butler first recorded planting the species on May 19, 1909 with plants from the Park Board Nursery and again in 1910, '11, and '14, same source. In 1918 one came from Pequot, MN. Red Pine is found in the NE part of North America from Virginia northward to Hudson Bay and as far west as Minnesota and Manitoba. In Minnesota it is native to the eastern 2/3rds of the state from Anoka county northward with several counties along the lower Mississippi reporting stands. It has been planted elsewhere for windbreaks, erosion control and landscape specimens. The Minnesota state record Red Pine was located in Itasca State Park.
There are three species of Pine native to Minnesota: P. banksiana, Jack Pine; P resinosa, Red (or Norway) Pine; and P. strobus, White Pine. The Scotch Pine, P. sylvestris, native to Europe has been introduced for landscape planting and for Christmas trees.
Uses: The wood is harder and coarser grained than white pine, nearly white in the sapwood. The primary use is construction lumber, poles, cabin logs and pulpwood.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"