Pine trees (Pinus) are a majestic addition to any garden. They have a pyramidal shape that sheds snow rather than piling it up, and their needles have a waxy coating to help retain moisture.
Plant a pine that’s appropriate for your climate, like eastern white pines (P. strobus) in the Northeast or ponderosas in the West. Some pine species have thin bark to resist crown fires, while others have thicker bark to tolerate surface fires.
P. strobus
Pyramid Shape
Pine trees have a distinctive pyramid shape that provides them with both structural and aesthetic appeal. They have a wide base that narrows in height to a sharp point, or apex, giving them stability while supporting lateral loads and resisting torsional forces. Pyramid shapes are often employed as a design element in both contemporary and traditional architecture.
Pyramids have a flat polygon base and triangular faces that connect to the point, or vertex, at the top of the pyramid. The number of sides on the base determines how many triangles make up the lateral faces of the pyramid. The points where the lateral faces meet at the vertex are called vertices. A pyramid can also be right or oblique, depending on whether its apex sits above or below the center of its base.
The pyramid shape of a pine tree helps it shed snow. Instead of piling up, the heavy snow that could break branches slides off the tree and leaves it standing tall in a storm. The pyramid shape also reduces wind resistance, allowing the pine to stay strong and upright in even strong winds.
Although the pyramids most people are familiar with are square, a pyramid can actually have any regular polygon for its base and still be considered a pyramid. The number of faces, edges and vertices can vary from pyramid to pyramid as well.
Teachers can use our printable worksheets to test students’ knowledge of the characteristics of pyramids, including how many lateral faces, vertices and edges they have. They can also learn how to calculate the slant height and base area of a pyramid, as well as how to differentiate a pyramid from a cube or other 2D shapes.
The pyramid shape of a pine is an important distinguishing feature, and it’s one that can be used to identify the species of pine. Other distinguishing features include its needles, cones, bark and geographic location. Pine needles grow in bundles of two, three or five and have a papery sheath at their base called a fascicle. This characteristic separates it from spruce and firs, which present their needles singularly.
Waxy Leaves
Luminous wax coatings give some plants a beautiful sheen, but they also serve an important function. Plants grow these coatings as barriers between themselves and the environment, protecting them from harsh conditions. The protective coatings can help trees retain water in hot environments, shield leaves from frigid temperatures and deflect the sun’s harmful ultraviolet rays.
The protective wax coating on pine needles, known as cuticle, is a key to the tree’s success. The cuticle reduces water loss by limiting the amount of water that escapes through the leaf surface, explains botanist Phil Gates. While some water does need to evaporate to keep the plant’s internal plumbing working, the process is slow and controlled by the cuticle. The layer consists of several different types of molecules, including cutin, a hydroxy fatty acid.
A pine’s needles are arranged in bundles called fascicles, with each bundle holding two to five needles. This arrangement distinguishes it from other conifers, such as spruce and fir. A pine fascicle’s tips point upward at first, then turn green and spread outward as they mature. Like the leaves of deciduous trees, pine needles capture sunlight and convert it into energy for the plant. However, unlike the broader leaves of deciduous species, the needles on conifers can better tolerate cold and snow.
When exposed to UV-B radiation, pine needles quickly develop the surface wax and compounds that protect them. These molecules reflect the damaging light away from the leaves, and they absorb the UV-B rays themselves. In tests, spruce and pine trees that were exposed to the rays for three years developed thicker cuticles and more UV-screening chemicals.
A tree’s texture can tell you a lot about its environment, says botanist Mark Browning. The texture of a leaf can indicate whether it grows in dry, hot conditions or wet, shady areas. A rough, brittle leaf is likely to live in dry, desert-like conditions, while a smooth, shiny leaf might prefer humid, tropical climates. The difference between these conditions may be the result of differences in a plant’s genetics or its environment, notes Browning.
Long Taproot
Pines, including the spruce and fir, have long taproots. This structure helps them to absorb water and nutrients from deep in the soil. The root system is generally fibrous with a large percentage of lateral roots. Pines also have a special type of root known as a fusiform root that is wider in the middle and narrower at both ends, similar to the shape of a spindle. This type of root is specialized to store starch, a major energy source for the tree.
The bark of pines is usually thick and scaly, though some species have thin bark. Pine branches often appear to be growing in a “pseudo whorl” pattern, actually a tight spiral that resembles a ring of branching. This pattern is characteristic of conifers and makes them very easy to identify. The cones of most pines open at maturity, and the seeds are dispersed by animals and wind. In some species, the scale bearing the nutlike seed may be expanded to form a wing for airborne dispersal.
Most pines require well-draining, sandy to acidic soil. Depending on the site, a pine tree can grow to 30 feet or more in height and 20 feet or more in spread at maturity. Pines are less likely to be severely affected by salt spray than other conifers, making them invaluable for stabilizing sand dunes and beachfront plantings. They are also widely used for accent trees, bonsai and hedges.
A mature loblolly pine (Pinus taeda) grows to 40 to 90 feet, though it is typically shorter under landscape conditions. Its needles are grouped two to five together and 6 to 10 inches long, and its cones are solitary and 3 to 6 inches long. Loblolly pines are among the fastest-growing Southern pines and can grow more than 2 feet per year.
Mugo pines (Pinus mugo) are recumbent shrubs or small trees a meter or two tall that root occasionally at their kneelike bends when they rest on the ground. These trees are common in the Alps and Siberia, where they supply valuable timber and are harvested for their oil. Mugo pines are susceptible to rust, wood rots, borers and sawflies.
Pollination
Pines (Pinus) are a group of evergreen conifers with distinctive cone-shaped fruit. They are a vital component of taiga and other coniferous forests, and they are often iconic or characteristic of individual ecosystems in the tropics and in North America.
The most obvious feature of a pine tree is its needles, but the plant also produces abundant pollen in spring. This pollen is one of the major contributors to seasonal allergies, especially in areas with large numbers of pine trees.
To reproduce successfully, pine trees must first be pollinated by another pine tree. To achieve this, the male and female cones are produced in separate trees and separated by the branches, with male catkins producing pollen and female cones producing seeds. The pollen from the male catkins is dispersed by wind currents to fertilize nearby female cones, completing the first step in reproduction.
Fertilized ovules in the female cones eventually develop into the winged pine seeds we are familiar with. The process is slow, however, and it may take two years before the seeds are mature enough to be released.
In the meantime, the seeds are sheltered in a cone-shaped vessel called a pyrophyte. The pyrophyte is composed of spirally arranged scales that close together and form a hard exterior shell to protect the seeds inside.
The scales open to receive pollen from the ovule-bearing male cones in spring, and the hardened pyrophyte then closes. This pyrophyte is the source of the yellow haze that many experience as a seasonal allergy to pine pollen in spring and early summer.
Pine pollen is big enough to see, and under a microscope it looks otherworldly, with two air-filled extensions that function like balloons to keep the grains afloat on air currents. Pine pollen has a short distribution period in the spring and summer, allowing it to be carried quickly from a tree to another to fertilize seeds.
As the name suggests, pines are native to most of the northern hemisphere, and they are an important part of taiga, coniferous, and mixed forests. The trees provide habitat and other ecosystem services, and the seeds they produce are a food source for birds and squirrels.
