Conifers Flashcards
White Fir
Abies concolor
Plant Description
Abies concolor, or White Fir, is a medium to large coniferous evergreen tree, growing 30-50 feet high and 15-30 feet wide. It has a strong upright pyramidal form with a dense branching habit. The newer branches on the top of the tree arch upward, while the bottom branches are held parallel to the ground. It prefers well-drained soil with regular moisture. It is tolerant of most soils (except heavy clay) and conditions and is somewhat drought tolerant.
The furrowed bark is gray-brown in color and forms in plates. Young bark is smooth and has small blisters filled with fragrant sap. First year growth is light green and slightly pubescent, but turns more of the typical gray color by the second year. The foliage is composed 1 1/2 - 2 1/2 inch long needles that curve upwards and are oriented towards the end of the stem. They are glabrous and flattened, with a rounded tip.
The cones are cylindrical, tapering to a bluntly rounded tip. They have layers giving them the appearance of a traditional beehive. They are light green in color before turning a purplish-brown color. They are 3-6 inches long and often exude resin.
Landscape Use
White Fir is an underused tree in the landscape that can provide both a good form and green color year round. It is exceptional for use as an accent tree in the landscape, or in layered wind break.
Points of Interest
Deer will browse on the tree during winter and can cause serious ornamental damage to young trees. Other than that there are no serious diseases or pests that threaten the tree.
Atlantic Cedar
Cedrus atlantica
Plant Description
Cedrus atlantica, or Atlas Cedar, is a medium to large evergreen tree (40-60 feet high and 30-40 feet wide). It has a somewhat stiff and sparse branching habit, but a very picturesque form that creates a very striking image in the landscape. When young the tree has a fairly good pyramidal form. At maturity it becomes more spreading and often flat-topped - which is when it is typically considered to be the most stately in appearance. It is a zone 6 tree, but will grow in a protected area in zone 5 where it will not be subject to strong winter winds. It prefers to grow in rich and moist acidic soils in full sun. It can tolerate drier conditions and other soil types once established.
The bark is smooth and gray in color when the tree is young, before forming thick bark divided into plates at maturity. The foliage is composed of small (1/2 - 1 inch), bluish-green needles that have a slight curl to them. They are arranged in tight whorls that are densely packed on the upper side of the stems. The foliage is unique and quite ornamental.
Both male and female cones form on the tree. The male cones are only 2-3 inches long and are oblong in shape. They are initially a light green color before turning a deep brown. They are held erect above the stems and tend to be more numerous in the lower branches of the tree. Typically held higher in the tree, the female cones are larger (4-6 inches), but are also oblong shaped and held upright. They have a multi-layered appearance. They often secrete quite a bit of resin, which can cover the cones and give them a shimmering appearance. They are light green in color before maturing to a purplish color and finally a rusty brown color. The cones open starting at the top and will slowly erode away down to the base.
Landscape Use
Use Atlas Cedar as a focal point in the landscape. Its rugged beauty will become lost in a large clumping of trees, and is better suited to being a specimen tree.
Points of Interest
Winter die back, or at least needle kill, is common in a colder winter, but otherwise it has few pests in our climate.
Notable Cultivars
var. glauca Pendula: A strongly weeping form with blue-green foliage. It needs to be staked for a good central leader to form. With training it can form a cascading mound or a elongatd serpentine habit. It is one of the best specimen plants I know of.
Norway Spruce
Picea abies
Plant Description
Picea abies, or Norway Spruce, is a medium to large coniferous evergreen tree, growing 40-60 feet high and 25-30 feet wide at maturity. It has a strong narrowly pyramidal form when young, but often fill out to a more upright form with age. The branches are held perpendicular to the trunk or angled slightly upward, with pendulous branchlets on each branch. It has a fairly open form, which tends to become more exaggerated with age. Norway Spruce thrives in full sun in well-drained soils. While it prefers acidic soils, it is not particular and will perform well in alkaline soil. It needs regular irrigation the first couple of years, but becomes quite drought tolerant after that.
The bark is gray brown in color and can have some reddish overtones. It forms in small plates that exfoliate, revealing a deeper red bark underneath. The needles are bright green to dark green and 1/2 - 1 inch long. They are arrayed around the stem and point slightly towards the stem tip.
Small, pale pink female flowers resembling a cone form at the terminal buds. This matures into the cone, turning brown and hanging from the tip of the branch. The female flowers and subsequent cones are much more plentiful at the top of the tree. The 1 inch male flowers form at the axillary buds and resemble bottlebrushes. The male flowers are less common.
Landscape Use
Use Norway Spruce in large landscapes, such as a campus or city park. They are also popular to use in wind breaks or for visual screening. I recommend clumping them with other trees, as the tree can become a bit sparse and ragged looking as it ages. They look best during winter when the snow stands out against their bright green needles.
Points of Interest
Picea abies is very susceptible to spruce gall aphid, which causes the formation of a brown gall on the tips of the branches. The galls are normally only an ornamental problem, but major infestations can stress the tree, causing it to grow slowly or become susceptible to other infestation.
They are also susceptible to borers.
Notable Cultivars
Pendula: An excellent weeping form. The form is unpredictable without training, each plant creating a unique specimen. It can grow 20-25 feet high with a widely variable spread.
Rubra Spicata: This dwarf variety has new buds that open in spring to reveal dark red needles. The good color last for a couple of weeks before slowly fading to green. It grows 10-15 feet high and 6-8 feet wide.
Sherwood Compact: Another dwarf cultivar with a good pyramidal form. It stays more dense than the regular species. It grows 12-20 feet high and 8-14 feet wide.
Cupressina: This variety has tight upright form and is a good selection for vertical evergreen accent. It grows 30-40 feet high and 10 feet wide.
Colorado Blue Spruce
Picea pungens var. glauca
Plant Description
Picea pungens, or Colorado Spruce, is a large coniferous evergreen tree, of which the most popular variety is Picea pungens var.glauca, or the Colorado Blue Spruce. It has a tight pyramidal form, growing slowly to 50-70 feet tall and 10-20 feet wide. In the wild it can reach twice that size. The branches are held out stiffly, with a very slight downward sweep. It is very adaptable to different types of soil and moisture conditions, and is one of the most drought tolerant species of Spruce. Plant in full sun for the best form and growth rate.
The bark is gray brown in color and matures to be very thick and corky. Large plates form on the trunk with deep fissures in between. The needles are blue-green, 3/4 - 1 1/4 inches long and stiff and prickly. They are more numerous on the upper side of the branch and curve slightly towards the end of the branch. The cones are an elongated oval shape and 2-4 inches long. They emerge green and can then turn a purple color before browning. The cone’s scales have an undulating surface and a finely toothed margin once the cone opens.
Landscape Use
Colorado Blue Spruce can be used as an accent tree thanks to its clear blue foliage, which adds some interest and variation to the landscape. It is well suited to use as a wind break of visual screen, but should be mixed with other tree and shrub plantings in both instances. It is best if it is kept away from (or pruned up) walkways due to the prickly needles.
Points of Interest
Picea glauca is also very susceptible to spruce gall aphid, which creates brown galls on the tips of the branches. The galls are normally only an ornamental problem, but major infestations can stress the tree, causing it to grow slowly or become susceptible to other infestation. Spider mites can also be a problem.
There is a great deal of variation in the needle color of Colorado Blue Spruce. One specimen may be very blue, while another can be nearly green in color. Sticking with a cultivar propagated by cuttings is the best way to get uniform color across multiple specimens.
Notable Cultivars
Baby Blue Eyes: A very slow growing compact cultivar of Picea pungens var. glauca. It grows in a nearly perfect christmas tree shape. 12-15 feet high and 6-8 feet wide.
Fat Albert: Is a moderate sized pyramidal form of the Colorado Blue Spruce and grows 30-40 feet high and 10-20 feet wide. The needles have a very good and consistent blue hue.
Iseli Fastigate: A good columnar cultivar perfectly suited for a narrow space or as a screen or wind break. It has a cigar-shape with strongly upward arching branches. It grows 10-15 feet high and 5-7 feet wide.
Sester Dwarf: A very compact and dwarf variety. It grows very slowly and only reaches 8 feet tall and 4-5 feet wide. The needles are a vibrant blue color. It is an expensive plant because of its slow growth rate and the royalty fees established by Sester Nursery, which developed it.
Bristlecone Pine
Pinus aristata
Plant Description
Pinus aristata, or Bristlecone Pine, is a small and rugged coniferous evergreen tree. It can reach a height of 40-60 feet tall, but it would take hundreds, if not a thousand years to do so. It is one of the oldest living plant on the planet, growing to be 4,000 - 5,000 years old. It has a loose and irregular growth habit that creates a rugged and picturesque appearance. A very rugged tree, it grows best in dry, well-drained soils in full sun.
The bark is gray-brown in color and smooth. The bark can peel away and expose the red colored wood beneath, before it weathers to gray. The needles form in clusters of 3-5 needles and angle noticeably towards the end of the branch. They are a dark green color and have white spots from discharged resin. The needles form densely on the branches and they resemble a bottle brush. The cones are 3.5 inches long and nearly egg-shape in form. They are dark purple-brown color and have small slender thorn-like tuft at the tip of each scale of the cone.
Landscape Use
The Bristlecone Pine is good for use as in a rock garden or other similar dry and harsh climates. The true beauty of these trees is their rugged and twisting form - which is hard to recreate under cultivated conditions.
They are often used in containers as an accent plant for a patio, where they are shaped and trained into an interesting form similar to a bonsai or topiary.
Points of Interest
This is a difficult species to find commercially, again due largely to their slow rate of growth.
Pinyon Pine
Pinus edulis
Plant Description
Pinus edulis, or Pinyon Pine, is a small coniferous evergreen tree or large shrub. It branches very low to the ground with a spreading form, giving it the appearance of a multi-stemmed tree, but it is in fact strongly single-stem in its habit. It is a rugged tree, growing in dry and rocky soils. It has an irregular form that is generally considered poor, especially aesthetically.
The bark is reddish-brown with some intercrossing furrowing. Young bark is more scaly in appearance. The green needles are bunched in paris and arrayed around the stem. They curve prominently towards the end of the stem. The green cones have triangular scales that protrude prominently from the cone. While the cones are still closed, resin seeps from them. They turn brown and open widely.
Landscape Use
Its poor form limits its use in the landscape. Use it in dry and rocky locations and in a naturalized landscape setting.
Points of Interest
The nuts from the pine cone are edible and a popular culinary treat.
Limber Pine
Pinus flexilis
Plant Description
Pinus flexilis, or Limber Pine, is a medium-sized evergreen tree with a strongly pyramidal habit for much of its life. It grows 30-50 feet tall and 15-35 feet wide. The branching is dense when young, but becomes more spreading as it matures, and old trees have a broad and spreading form. It grows in well-drained soil with regular irrigation, but is drought tolerant once established. It is a tough tree that will handle an exposed setting well and consistent growth and form.
The bark is gray and forms in small plates. Young bark is smooth and often has a greenish hue to it. Young branches are very flexible and can be easily bent back on to themselves, hence the common name of Limber Pine. The dark blue-green needles are long (2.5 - 3.5 inches) arranged in clusters of 5 that point towards the end of the stem. The needles are sparse on the stems and much more profuse at the end of the stem, giving the tree a tufted appearance. The light brown cones form in clusters of a little below the terminal bud. They are 3-6 inches long and narrowly ovoid in shape. Resin commonly extrudes from the cones.
Landscape Use
Limber Pine has an excellent form, especially when young, that is handsome in the landscape. Use it with other trees and shrubs to create a good windbreak or screen. It is also a choice for use in a naturalized setting and any location that has poor growing conditions.
Points of Interest
It is susceptible to very few pests or diseases, and none of them are serious. Its flexible branches are an asset in dealing with strong winds and heavy snow loads, which it usually sheds off easily.
Notable Cultivars
Glauca: The needles are more of a blue color than the regular species.
Vanderwolf: A fast growing selection of the species (about 2 feet per year), it has a very good pyramidal form and upright branching habit.
Austrian Pine
Pinus nigra
Plant Description
Pinus nigra, or Austrian Pine, is a large coniferous evergreen tree, growing 50-60 feet high and 20-40 feet wide. Young trees are dense and have a good pyramidal shape, but they become more spreading and flat-topped with age. Mature trees are often very open in form and have long branches with a gentle weeping form. They are quite adaptable to a wide variety of soil and moisture conditions.
The mature bark is reddish-brown in color and has a wonderful flaky nature which produces a rich texture composed of large plates. Younger bark has a scale-like appearance to it, is more true brown in color, and has the spent needle base still attached to it. The needles are 3-5 inches long, dark green in color and quite stiff. They form in pairs.
Small yellow-green cone-like flowers, or pollen cones, form at the base of the new growth (candle). They turn brown once they are spent and can often be found on the ground around the tree. The pine cones are 2-3 inches long and shaped like a tapered egg. The cones stay on the tree for two years, ripening and opening at the end of the second year. The scales protrude out from the cone and are tipped with a tiny point. The cone turns brown when it is open and is the prototypical pine cone.
Landscape Use
Austrian Pine is an attractive tree, suitable for use as a stand-alone specimen but more suited to clustering or use as an evergreen shade tree. It is effective as both a screen and wind break when you, but becomes less effective as it matures and becomes more open in nature.
Points of Interest
Pinus nigra has no serious pests or problems in our climate. However, its shallow root system can be disruptive to sidewalks or roadways.
Ponderosa Pine
Pinus ponderosa
Plant Description
Pinus ponderosa, or Ponderosa Pine, is a large and fast growing coniferous evergreen tree growing 60-100 feet high and 25-30 feet wide. It has a narrowly pyramidal form when the tree is young, and as it matures the form becomes more upright in habit with a bluntly rounded top. The stem is very straight and the branches on mature tree are often held high off of the ground. The branches are typically held straight out from the trunk, but some may exhibit a drooping character. It prefers to grow in rich, well-drained soil with adequate moisture. It can tolerate our dry alkaline soils, but performs better in more moist acidic soils.
The bark is an interesting color contrast with the ridges being an brownish-orange color while the valleys are nearly black. The needles are true green and held in clusters of 3 needles. They are very long (5-10 inches) and end in a sharp point. The cones of the tree can occur singly or in clusters and are 3-6 inches long and shaped like an elongated egg. The tips of scales have a small protrusion similar to a thorn. When the cone opens it has the very typical pinecone look.
Landscape Use
Pinus ponderosa is a truly impressive tree, however its mature size makes it an unsuitable specimen for use in small or even moderately-sized sites. It is best used in large campuses and public parks, where it is in better scale to its surroundings.
It is popularly used along highways, especially in Pacific states, where it creates a sheltered and picturesque screen and setting. It is also useful as part of a larger wind break, or for erosion control.
Points of Interest
Pine beetle is becoming a major problem in the western United States, and has reached epidemic levels in several areas of the western coast.
Scotch Pine
Pinus sylvestris
Plant Description
Pinus sylvestris, or Scotch Pine, is a medium to large coniferous evergreen tree, growing 30-60 feet high and 30-40 feet wide. Like many other conifers, it has a pyramidal form when it is young, but becomes broad and spreading as it matures. Mature trees begin their branching far up the trunk and hold their branches in a strongly horizontal manner. It is prone to developing a rather loose and open habit that can be quite picturesque in appearance. It grows best in well-drained soil in full sun. It has a slight preference for acidic soils, but truthfully is tolerant of most soil conditions, even very poor soils.
The bark exfoliates and is a prominent ornamental feature of the tree. It is reddish-brown and forms in plates and fissures near the base of the trunk. On the upper two-thirds of the trunk the younger bark is a vibrant orange color. The needles are grouped in pairs. They are a deep blue-green color and 1-3 inches long. They are quite stiff and regularly have a twist or curve to them.
The cones normally form singly on the tree and are reflexed on the stem, meaning that they point towards the base of the stem instead of outwards or towards the tip on the branch as is common on most other conifers. The cones are 1 1/2 - 3 inches long and conical in shape. Pyramidal protrusions form on each scale on the cone.
Landscape Use
Use as a specimen tree in the landscape. Its rugged and open form is accented by its very ornamental bark. Its size makes it less suited for use in a residential setting; larger lots or parks and campuses are ideal.
Points of Interest
In large parts of the country, Scotch Pine is highly susceptible to Pine Wilt and Sphaeropsis tip blight, but neither are problematic in our climate.
Himalayan Pine
Pinus wallichiana
Plant Description
Pinus wallichiana, or Himalayan Pine, is one of the most delicate and graceful conifers. It reaches 30-50 feet high and 20-30 feet wide. It has a loose pyramidal form with branches held close to the ground. While it is hardy to our climate, needle damage may occur during cold winters, and it should be planted in a protected location if possible. It grows best in well-drained slightly acidic soils and is drought tolerant once established. The mature bark of the tree is gray-brown in color and forms in rough plates that have curl on their edges. Young bark is a silvery-gray color and it is smooth. The mature bark forms in an irregular pattern on the branches, creating an interesting texture along the branch.
The beautiful long needles are 5-8 inches long and held in clusters of five. They are soft to the touch and hang gracefully from the branches. They are a light gray-green color that adds to the visual softness of the plant. The cones are cylindrical and tapered at the point. They are 6-10 inches long and held below the branch on noticeable 2 inch long stalks. Immature cones are a pale green color and resinous. Mature cones turn light brown.
Landscape Use
Pinus wallichiana is perfectly suited for use as a specimen tree. Its low branching habit and broad form make it perfect for use as a large and graceful backdrop to a shrub or perennial border. It is not suitable for a wind break because of cold hardiness issues. It is well adapted to an urban setting because of its high tolerance of air pollution and soil adaptation.
Points of Interest
Keep Himalayan Pine out of direct winds or very cold microclimates.
Douglas Fir
Pseudotsuga menziesii
Plant Description
Pseudotsuga menziesii, or Douglas Fir (often listed as one word: Douglasfir), is a large coniferous evergreen tree growing 40-80 feet high and 12-20 feet wide. It has a very narrow form, more columnar than pyramidal except when young. The branches are held out horizontally with the branchlets weeping from them, similar to Picea abies. On mature trees, the lower half of the trunk may be bare. Douglas Fir prefers moist, well drained acidic soil. It grows best in moderate and humid climates such as the Northwest. While it will tolerate our climate, it is best if it is kept in a location that will offer it some protection from dry winds.
The bark is reddish-brown color and has deep ridges and furrows. Young stems have smooth bark with resin blisters on it. The needles are composed 1 - 1 1/2 inches long and can arranged on the stem either radially or in two ranks. The bottom side of the needles has two pale strips on it. The needle has a slight indent running the length of it. They are bluish-green in color. Dirr notes that the Pacific coastal strain of Pseudotsuga menziesii has green needles, but the plants of these species are not hardy in our climate.
The cone is 3-4 inches long and have an elongated oval form. Three-pointed bracts protrude from beneath the scales of the cones. They are lime green with reddish highlights when immature, and turns reddish brown when it matures.
Landscape Use
While it is an attractive specimen, it does not perform as well in our climate as other conifers. Its narrow form makes it ideal for use in tight spaces, but it can reach massive heights that may appear out of scale in such a setting. It looks best when used in groupings instead of singly.
Points of Interest
Perhaps the most recognized use for Pseudotsuga menziesii in the western United States is as a Christmas tree.
