Evergreen Shrubs and Small Trees Flashcards
Horizontal Juniper
Juniperus horizontalis
Plant Description
Juniperus horizontalis, or Horizontal Juniper, is a low and dense spreading coniferous evergreen shrub. It thrives in hot, dry locations, but will perform well under damp conditions as well. It grows 1-2 feet high and 4-8 feet wide, with long trailing branches the stay close to the ground. It forms a dense mat that is very effective as a groundcover and choking out other plants. It is one of the most over-used species of plants, especially in commercial landscapes, and but has largely fallen out of favor with private consumers. The bark is a red-brown color and exfoliate with age.
The foliage is composed of shiny dark green scale-like leaves. Young leaves have an awl-like shape while the mature leaves are scales. The small scales are arranged in ranks of four around the stem. The leaves are very small, less than 1/6 inch long and blue-green in color. In the winter, they turn a slight purple color, with the change more pronounced in certain varieties. The plant develops small blue fruits 1/4 - 1/3 inch in diameter. The fruit are actually cones, but look like berries.
Landscape Use
Use as a dense groundcover or for erosion control. It is especially popular as a foundation planting, for use in parking islands, or any other dry and hot locations. While it is still immensely popular as in commercial plantings, especially for its weed suppression ability and ease of care, it has gained a reputation as being a spider-nest and tired plant.
Notable Cultivars
Youngstown: This cultivar grows up to 2 feet high and spreads up to 8 feet. The foliage is gray green and turns a rich purple in the winter.
Mother Lode: The foliage on this variety is variegated green and yellow. It stays lower to the ground and only spreads 3-4 feet wide.
Wiltonii: Also known as Blue Rug, it is an old and popular variety. It grows only 6 inches tall and spreads to 8 feet wide. The foliage is a silver-blue color, as are the cones. In the winter the foliage turns a purplish color.
Chinese Juniper
Juniperus chinensis
Plant Description
Juniperus chinensis, or Chinese Juniper, is a tall upright evergreen tree, but there are many shrub cultivars. It grows 50-60 feet high and 15-20 feet wide, typically developing a slender but irregular outline. It can occasionally form a smaller and bushier large shrub. Unlike many other species of Juniperus, Chinese Juniper prefers moister soil conditions, though it becomes more drought tolerant with maturity. The bark is gray-brown in color and exfoliates in strips. Mature bark develops ridges and furrows.
The foliage is green to grayish-green in color and composed of small needles, awl-shaped when young and scale-shaped when mature. The awl-shaped young leaves are 1/3 inch long and form in a trio and arranged in whorls. The mature leaves are scaled in 4 ranks around the stems and very short (1/16 inch long).
Chinese Juniper has both male and female fruit. The male cones are brown and are usually to be found only on mature branches. They are profuse on the tree. The small female berries are a silvery-blue color.
Landscape Use
The regular species can be used in tight columnar spaces to provide some winter access. There are several smaller varieties than are suitable for ground covers or foundation plantings.
Notable Cultivars
Sea Green: A medium sized shrub form of Chinese Juniper. It grows 4-6 feet high and 6-8 feet wide. The foliage is a bright and minty green color.
Spartan: An upright variety that grows 12-16 feet tall and 6-8 feet wide. It has a good tapering form and dense habit. Image: University of Florida
Tam or Savin Juniper
Juniperus sabina
Plant Description
Juniperus sabina, or Savin Juniper, is a medium sized evergreen shrub growing 4-6 feet high and 5-10 feet wide. The branches of Savin Juniper are held at a distinct 45 degree angle, creating a low vase shaped form. Despite the strong structure, the plant has a somewhat ragged appearance. It performs well in our alkaline soils and prefers a hot and dry location in full sun.
The foliage is composed of scale-like leaves that are ovate in shape. They are dark green with a slightly glabrous appearance. They are arranged in overlapping opposite pairs. The young foliage is awl-shaped and sharply pointed. The foliage has a foul odor when it is crushed. The fruit is composed of berry-like scaled cones and it is blue or black in color and globose.
Landscape Use
The regular species of Juniperus sabina is not widely used, but several of the cultivars are good for use as groundcovers and foundation plantings.
Points of Interest
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Notable Cultivars
Broadmoor: This dwarf variety has a light gray foliage. It only grows 2-3 feet high and spreads up to 10 feet or more.
Calgary Carpet: Light green foliage and with a very low growing form. Spreads up to 10 feet wide.
Rocky Mountain Juniper
Juniperus scopulorum
Plant Description
Juniperus scopulorum, or Rocky Mountain Juniper, is a native coniferous evergreen tree. It is a famously rugged and tolerant of poor soils and drought conditions. It grows 30-40 high and 3-15 feet wide with a narrowly pyramidal form. It can be a single stem tree, but regularly has multiple stems. The bark is a gray-brown color and exfoliate in strips. It is somewhat ornamental when visible.
The foliage is light green to gray-green in color. Young foliage is needle-like and arranged oppositely or in whorls. The mature foliage is scale-like in shape and tightly pressed together. The small berry-like cones are dark blue in color and have slight sheen.
Landscape Use
The regular species is most suited to use in a naturalized setting. Several cultivars are good to use as a hedge or foundation plantings.
Points of Interest
Cankers can be problematic. The Jardine Juniper, a specimen of Rocky Mountain Juniper over 1,500 years old, can be found in Logan Canyon.
Notable Cultivars
Skyrocket: This cultivar has a good pyramidal form with silvery gray foliage. It grows 10-15 feet tall and 3-5 feet wide.
Bird’s Nest Spruce
Picea abies ‘Nidiformis’
Plant Description
Picea abies ‘Nidiformis’, or Bird’s Nest Spruce, is a small coniferous evergreen shrub that is a cultivar of Norway Spruce (Picea abies). It grows slowly to be 3-6 feet high with a slightly greater width. It has a very dense branching habit, with a depression in the center of the shrub that makes it look as if a bird was nesting in the shrub. It prefers to grow in a well-drained soil with regular moisture provided. Once established it is quite drought tolerant.
The stiff needles are dark green in color and 1/2 - 1 inch long. The needles form all the way around the stem and tend to be angled forwards, towards the end of the branch. Most needles are straight, but some can exhibit a slight curl. In the spring, the new growth emerges a distinctly lighter green and the needles are soft and pliable.
Landscape Use
Bird’s Nest Spruce is a popular plant for foundation plantings. It is also popular in commercial plantings and is regularly seen in parking islands. It is a good evergreen choice for residential lots because of their small and compact size.
Points of Interest
In my experience, our heavy snow loads tend to cause the plant to have a more broad and spreading form and help to keep them compact and low to the ground.
Dwarf Alberta Spruce
Picea glauca ‘Conica’
Plant Description
Picea glauca ‘Conica’, or Dwarf Alberta Spruce, is a popular small coniferous evergreen tree, growing very slowly to 10-12 feet high and 5-7 feet wide. It is a cultivar of Picea glauca or White Spruce. They have a very dense branching habit and needle coverage, and a strongly conical form reminiscent of a Christmas Tree. It needs ample moisture when it is getting established, and always requires a moderate amount of moisture to prevent sun burn, but prefers well-drained soil. I have seen this cultivar perform well when planted in full sun or full shade.
The needles are small, 1/4 - 1 1/2 inches long, and bright green to blue-green in color. They radiate around the stem and curve noticeably towards the end of the branches. Despite the fluffy and soft visual texture of the tree, the needles are quite stiff and sharp. The terminal buds are small and swelled in appearance, and can be mistaken for cones, which rarely form on the plant.
Landscape Use
Commonly used as an accent plant because of its natural cone shape. It is commonly used as a foundation plantings, but should only be done so on the north or east side of a building to avoid damage to the foliage from reflective heat.
Points of Interest
It is damaged by salt, and so should not be used in a location where winter snow will be plowed onto it. Snow loads can damage the conical form and many people wrap them in burlap over winter. Mites can be problematic and, in bad cases, can lead to defoliation. Most damage to specimens in our climate occurs from a lack of water or from being subjected to high amounts of reflective heat or light.
Notable Cultivars
Rainbow’s End: The new growth emerges yellow, giving the tree the appearance that it has been dusted with gold.
Mugo Pine
Pinus mugo
Plant Description
Pinus mugo (Mugo Pine or Swiss Mountain Pine) is a mountain pine native to the mountain ranges of Europe. Its native form can grow up to 75’ tall, but the most commonly available commercial cultivars of Pinus mugo rarely exceed 15’, with large majority being in shrub form that is less than 6’ tall.
The 1-2” long needles grow in pairs and vary in color from light green to a deep green, depending on the cultivar. The upward arching form of the branches strikes an attractive figure in the tree form, and produces a very dense canopy in the shrub form. The Mugo Pine is very hardy (zone 2) and tolerant of many different soil, exposure, and moisture conditions, though it performs best in well-drained soils with full sun.
Landscape Use
The small tree or large shrub form of Mugo Pine was very popular twenty to thirty years ago as an effective screen. Its relatively small size and dense foliage made it especially suited for this use. Although the tree form of the Mugo Pine is no longer as widely used as it was, the species remains an important landscape plant thanks to its many small shrub cultivars which are popular for use as foundation plantings and compact evergreen accents.
Points of Interest
Mugo pine is susceptible to needle scale.
Notable Cultivars
Valley Cushion: A very compact, dense pine that stays low and flat, much wider than tall. Reddish, new buds complement the short, medium green needles, and plants grow very slowly, so they require little or no pruning.
Whitebud: Cold weather brings a white resinous coating to each terminal bud, producing a dramatic frosty effect against the plant’s dark green winter foliage. During the rest of the year, the reliably low, globe-shaped plant.
Columnaris: A very narrow, upright Mugo Pine, the compact columnar habit is open enough to show off interesting reddish orange bark. Conspicuous buds, coated with white, waxy resin, stand out against long, dark green needles in winter, and colors intensify as the seasons change.
Slowmound: The dense, dark green mound is one of the best, with highly reliable color, texture, growth rate and habit. Beautiful year-round, it produces many showy buds and matures to a wide, even shape that is naturally compact. Reaches only 1-2’ in 10 years.
Mops: The mounding plant has a smooth appearance that comes from many evenly spaced needles growing at a uniform rate on abundant branchlets. During most of the year, ‘Mops’ displays a hint of gray/blue in its green, but during the crisp, cold months of winter, needles take on a warm, golden hue.
Pumilio: A larger and faster growing cultivar, Pumilio can be expected to reach a height of 5’ and a width much larger. There is a high degree of variability in the size of Pumilio because it is often propogated from seed.
Tannenbaum: This perfectly formed Christmas tree shaped tree displays an exceptionally good habit and the tough constitution of other mugos. The needles are longer, in proportion to its larger size. Foliage is rich green with a hint of gray/blue, even during winter. Highly adaptable to a wide range of environmental and climatic conditions and very hardy. Can reach 10’ tall and 6’ wide after 25 years.
English Yew
Taxus baccata
Plant Description
Taxus baccata, or English or Common Yew, is a large evergreen tree or shrub, that is borderline for Cache Valley, even when planted in a protected microclimate. It will survive in other areas of the Wasatch Front where temperatures do not drop below -10 degrees. They are slow growing and have a lifespan measured in thousands of years. Taxus baccata reaches 30-60 feet high and 20-25 feet wide. It has a dense branching habit, with many wide spreading branches. The form varies greatly, from a large bushy shrub to a rounded tree or even a pyramidally upright tree. It prefers moist, well-drained soil and performs well in sun or shade, but not where it will experience extreme heat or cold. It should also be kept out of winter winds, which will quickly dry out the needles.
The bark is a reddish-brown color and exfoliates in small plates. Mature trees develop a clearly fluted trunk. The foliage is composed of soft needles 1/2 - 1 1/4 inch long. The needles are a dark, rich glossy green color. The needles spiral around the stem when grown in the sun, but form in two-ranks when grown in the shade. The fruit is composed of a single olive colored seed surrounded on all sides, except the bottom, by a fleshy red berry-like covering.
Male and female flowers both occur on the tree. The male flowers occur in tiny clusters, while the female flowers form singly. Neither are ornamentally important.
Landscape Use
Taxus baccata is used extensively in Europe in formal hedges, topiaries and as a shade tree. In our climate, it performs best when planted in the shade, and can be a valuable selection as a shade-tolerant evergreen.
Points of Interest
All parts of English Yew is highly poisonous if ingested. In the British Isles a fine specimen can usually be found in historic churches or monasteries, where they were planted to prevent farmers from allowing their cattle to graze on church property due to the toxicity of the plant killing the animals.
Species of Taxus remain one of the leading causes of horse and cattle poisoning. Do not plant where it may be eaten by livestock!
Notable Cultivars
Repandens: A dwarf cultivar with a low spreading form. It reaches 2-4 feet high and can spread up to 15 feet wide. The branches exhibit a slight weeping habit.
Japanese Yew
Taxus cuspidata
Plant Description
Taxus cuspidata, or Japanese Yew, is a small to medium coniferous evergreen tree, or large shrub. It grows slowly to 10-40 feet tall with a wider spread. There is a great deal of variation in its form, and it can be tall and upright to broad and spreading. It prefers to grow in moist, well-drained soil and performs better in soils that are slightly acidic. In our climate it grows best in part to full shade, but will grow in full sun in more temperate and humid climates.
The attractive bark is reddish-brown in color and exfoliate in small plates. Young stems are a light green color the first year, and turn reddish-brown the second. The foliage is composed of short (1/2 to 1 inch) and wide needles with a distinct point on their ends. The needles are a dark glossy green color on the top and a paler green below. While they are arranged on either side of the stem, their spacing and placement is not as symmetrical as on Taxus baccata. Needles are often arranged in a more alternate pattern or stray needles will form above or below the stem.
The fruit is composed of a single olive colored seed surrounded on all sides, except the bottom, by a fleshy red berry-like covering. Male and female flowers both occur on the tree. The male flowers occur in tiny clusters, while the female flowers form singly. Neither are ornamentally important.
Landscape Use
The most common cultivars are shrub forms that are suitable for use as a foundation planting, hedge or in mass plantings.Taxus cuspidat is a good selection for an evergreen that can tolerate full shade.
Points of Interest
All parts of Japanese Yew is highly poisonous if ingested. Species of Taxusremain one of the leading causes of horse and cattle poisoning. Do not plant where it may be eaten by livestock!
Anglojap Yew
Taxus x media
Plant Description
Taxus x media, or Anglojap Yew, is a hybrid between Taxus baccata and Taxus cuspidata. It is regularly smaller than either of its parent species, but exhibits the same great variation in form. It performs well in moist, well-drained slightly acidic soils. In our climate it is best grown in full to part shade. The cultivars of this hybrid species are the most commonly used Yews.
In appearance it is often identical to Taxus cuspidata except in a couple of features. First, the leaves are arranged in two well-defined ranks on the stem. Second, the stems retain their light green color for several years before turning reddish-brown.
Landscape Use
There are several different cultivars available with varying forms. Law and spreading forms are most commonly used as a foundation plantings, while upright forms are used for hedges and screens.
Points of Interest
All parts of Anglojap Yew is highly poisonous if ingested. Species of Taxusremain one of the leading causes of horse and cattle poisoning. Do not plant where it may be eaten by livestock!
Notable Cultivars
Hicks: Among the most popular of the narrow and columnar cultivars. It grows 20 feet high and 8 feet wide. It typically has two main leaders, which can cause lead to serious breakage under our winter snows.
Dark Green Spreader: The most popular spreading cultivar. It grows very dense and is good for use as a low hedge. Grows 3-4 feet high and 6-8 feet wide.
Citation: Similar in form to Hicks, but it regularly has a single leader, so snow loads are less likely to break the limbs. Grows 15-20 feet high and 6-8 feet wide.
American Arborvitae
Thuja occidentalis
Plant Description
Thuja occidentalis or American Arborvitae, is a hardy, medium-sized evergreen tree reaching 20-30 feet high and 10-15 feet wide. It grows best in a temperate and humid climate and in rich, moist soils. Once established, it will tolerate a drier condition and our alkaline soils, but they always need regular water to keep them healthy. Plant in full sun.
The bark is narrowly furrowed and two-toned. The ridges are gray while the furrows are a reddish-brown color. It may exhibit a slight exfoliating nature, with the bark peeling in long strips. It is a somewhat ornamental feature, but not outstanding and usually hidden by the foliage.
The foliage is composed of small scale-like needles that overlap each other and hug the stem tightly. They are true green to dark green in color. In the winter the foliage may turn a yellow or even an unattractive brown color. Small cones up to 1/2 inch long and composed of overlapping scales form on the limbs. They are egg-shaped and begin greenish color before ripening to a brown. They are normally born in small amounts and not noticeable.
It can be difficult to tell the difference between Thuja occidentalis and Thuja orientalis. The easiest method to tell the two species apart is to look at the orientation of the foliage. If the foliage is held in horizontal planes, it is Thuja occidentalis, if it is held in vertical planes than it is Thuja orientalis. While this is a good general rule, be aware that it does not hold true for all of the cultivars.
Landscape Use
It is most widely used as a screen or hedge, thanks to its dense evergreen foliage and upright habit. Smaller cultivars can be used as foundation plantings. Similar to Junipers, Arborvitae has been overused and has fallen out of favor, especially with private consumers.
Points of Interest
Thuja occidentalis is like cotton candy for deer and will is a favorite for deer foraging in yards over the winter. They can literally be stripped clean of foliage in a matter of days if not protected. Snow damage can lead to branch breakage, so it is best if the plants are wrapped in burlap (or at least tied up) over the winter.
Needle burn is also a major problem in our climate, and it is especially troublesome during the winter with the reflective light. Spider mites can be problematic.
Notable Cultivars
Degroot’s Spire: A tight and narrow form and spiraled branchlets that create a wavy texture. It grows 6-12 feet tall and 3-5 feet wide.
Hetz Midget: A small, slow-growing and globe-shaped cultivar with dark green foliage. It does not require pruning to maintain its good globe shape. It grows 3-4 feet high.
Holmstrup: This smaller cultivar has a strong pyramidal form and good bright green foliage that it retains through the winter. Grows 5-6 feet tall and 2-3 feet wide.
Linesville: Also known as Mr. Bowling Ball. A small, globe-shaped cultivar with light green foliage and a more airy branching habit. I prefer the texture and color of Linesville to Hetz Midget. Grows 2-4 feet high and wide.
Oriental Arborvitae
Platycladus or Thuja orientalis
Plant Description
Thuja orientalis (recently reclassified as Platycladus orientalis), or Oriental Arborvitae, is a large shrub or small tree, growing 18-25 feet tall and 10-15 feet wide. It has a dense, pyramidal shape, but often exhibits a more open and spreading form. It prefers moist, well-drained soil and full sun. The bark is gray with brown highlights and has thin but deep furrows. The bark has a rugged charm about it, especially on large mature specimens. Younger bark is a reddish-brown color and exfoliates in long, thin strips.
The foliage is true green to yellow-green in color and composed of small triangular overlapping scale-like needles. They are closely pressed to the stems. In the winter the foliage can discolor slightly. The fruit is composed of powder blue-green, fleshy, overlapping scales. They are ovoid in shape and have several irregular horn-like projections on them.
Landscape Use
Larger cultivars can be used as a specimen tree. Most often it is used as a hedge or a screen. Somewhat over-used in the landscape, it is less popular than it used to be.
Points of Interest
Like Thuja occidentalis, Thuja orientalis is a popular winter food for deer. The winter can take a particularly harsh toll on Oriental Arborvitae. The snow can cause severe branch breakage and should be wrapped to protect the limbs and the form. Winter winds can also quickly dry out the foliage.
Notable Cultivars
Aurea Nana: A small and compact cultivar with an upright rounded form with yellow to yellow-green foliage. It grows 5-8 feet tall.
