Genus Pinus Classification and Features

The genus Pinus refers to the group of evergreen conifers commonly known as pines or pine trees.  Of the family Pinaceae, Pinus is one of the largest genera and has over 100 species found world wide.  Members of this genus can be found mainly inhabiting temperate climates but there are a few species that are especially adapted to living in arid conditions as well as alpine regions of mountains. 

All pines have needle-like leaves that may come in clusters of two, three, five, or as a single needle.  All pines also produce cones that are commonly referred to as pine cones which is where the seed develop to maturity.  Species of pines are very diverse with some species reaching heights of over 200 feet while others sprawl near the ground as shrubs. 

The genus Pinus can be broken into three distinct categories, also known as sub-genera, in order to classify species that share common traits. These sub-genus classifications are based on leaf cross-sections, seed wing formation, and cone structure.  Sub-genus Strobus includes pines known as soft or white pines that have five needles per cluster.  Sub-genus Pinus includes hard or yellow pines that have needles in bundles of two or three.  Sub-genus Ducampopinus includes the pines that have a combination of characteristics from the other two categories and includes the foxtail and pinyon pine.

An example of a pine belonging to sub-genus Strobus would be the Eastern White Pine, Pinus strobus, which is found in Eastern North America.  It has long, soft needles that are 3-5 inches long of a blue-green color in clusters of five.  An important timber species, this pine will grow to over 100 feet tall and has a straight trunk. 

The ponderosa pine, Pinus ponderosa, is currently the record holder of the world’s tallest species of pine and is a member of the Pinus sub-genus.  Found in Western North America, the ponderosa pine is capable of reaching heights of over 200 feet tall and has dark green needles, 4-8 inches in length, in clusters of two to three. 

The singleleaf pinyon, Pinus monophylla, is an example of of the sub-genus Ducampopinus and is one of the types of pines that produces edible seeds known as pine nuts.  As its name implies, the singleleaf pinyon only has one 1-3 inch needle per cluster.  This tree is native to South Western North America and can be found primarily in parts of California, Nevada, Arizona and Utah. 

Pines serve an important function for forestry, horticulture, and the ecology.  The wood of many pine species is used as building materials as well as for furniture and other forest products.  There are hundreds of cultivars of pines that serve as beautiful ornamental plants in gardens and landscapes all over the world.  Pines are an important species for native wildlife who depend on the stands of pine trees for food, shelter and nesting sites.