Native Trees and Shrubs Flashcards
Bigtooth Maple
Acer grandidentatum
Plant Description
Acer grandidentatum, or Bigtooth Maple, is a small to medium tree or large shrub that grows natively in the hills and mountains of the intermountain west. It can grow to 30-40 feet high, but many specimens in the wild grow to only 25 feet. It is often found in a multi-stem form in the wild, but tree-form is available in limited quantities commercially. It has a spreading form, with a moderately dense canopy. It is widely adaptable to soil and moisture conditions, but will not tolerate a complete drought location.
The bark of the tree is a pale brown color. It has very slight ridges and furrows, and from a distance can appear as smooth. The samaras wings of the samaras are held in a straight line, with the seeds forming above it. The wings will turn a papery brown before the seed.
The leaf has three or five mildly rounded lobes (the small pair of lobes at the base of the leaf may not form) with and is deeply cut. The margin of the leaf has large, irregular teeth serrations. The has a palmate venation pattern which can be used to determine if the individual leaf has three or five lobes. The leaf is three-four inches wide and bright green. In the fall the leaves turn a brilliant orange or red color, clearly visible in the canyons during fall.
Landscape Use
The multi-stem form can be used in restoration projects or in naturalized plantings. It is also a good selection for incorporating into a wind block. The tree form is suitable for use as a parking strip tree or lawn tree. Plant it in masses to really take advantage of the fall color.
Points of Interest
Bigtooth Maple can be tapped for syrup like Sugar Maple can.
Boxelder
Acer negundo
Plant Description
Acer negundo, or Boxelder or Ash-leaved Maple, is a large and hardy shade tree that many consider a trash tree because of its insect problems and weak wood. It grows 30-50 feet high with a slightly wider spread. It has a broadly rounded form, usually with a great deal of irregularly in the crown. It grows natively in moist conditions, but is highly adaptable to nearly any soil or moisture condition.
The bark is gray with tightly spaced deep ridges and furrows. New growth has a reddish overcast to it. Yellow-green flowers appear in the spring. Male flowers are in small clusters and female flowers are in hanging racemes. Neither could be considered ornamental. The samaras are held in paris at a steep angle. They form profusely in long chains and drop from the tree in October. New seedlings emerge in copious amounts.
The bright green leaf is opposite pinnately compound and 5-8 inches long. It has 3-5 leaflets, each leaflet being ovate in shape and roughly serrated. The leaf is similar in appearance to that of Fraxinus pennsylvanica. The leaves turn an unimpressive dull yellow or brown color in the fall.
Landscape Use
I recommend not using Boxelder except in particularly difficult locations, where the tree is well-suited. It is a maintenance liability and not particularly an attractive tree. Locations with poor soils, and extremes of either drought or damp are ideal locations. Use it as a last resort.
Points of Interest
Boxelder is famous for being attractive to Boxelder bugs, which feed on the tree, and anywhere the tree is planted is sure to see a herd of the insects. It also regularly develops large burls on the trunk that give it an unsightly appearance. Acer negundo has brittle wood that often breaks in wind or under the weight of snow.
Notable Cultivars
Flamingo: One of the few cultivars worth considering for use as a shade tree or lawn tree. The leaf is variegated with green and cream, with the new leaves and shoots being tinged a pure pink. It grows 25-30 feet high and wide. Branches that have reverted to regular green leaves emerge regularly and should be pruned out immediately.
Common or Black Alder
Alnus glutinosa
Plant Description
Alnus glutinosa, or Common or Black Alder, is a medium sized shade tree with an upright form. It grows 40-60 feet high and 20-40 feet wide. When young the tree has a fairly strong pyramidal form, but becomes quite irregular and upright at maturity. It can be found in both a multi-stem form and regular tree-form, both of which are attractive. It naturally occurs in small groupings of trees. It prefers moist locations, and can tolerate standing water. It will survive in a dry location, but not severe drought. Young bark is silvery-brown and has prominent horizontal lenticels. As the bark matures it turns a dark brown and forms ridges.
The leaf is ovate in shape with a doubly serrated margin. The leaf is a dark green color on the top and a bright green color beneath. The leaves are 2-4 inches long and form alternately on the stem. 2-4 inch long narrow brown catkins form on the tree in groupings of three or more. Purplish colored small strobile are shaped like eggs and form in groupings on the stems. Up close they provide an interesting and unique texture to the tree that is quite attractive. In the fall the strobiles turn brown and open to release the seeds. The strobile will persist on the tree throughout the winter.
Landscape Use
It is best used in moister areas. If used along a stream bank the tree will quickly spread and fill in to create a dense colony. It is good to use as a tree in parks and campuses, and can be used on residential lots thanks to its narrow width.
Points of Interest
It is susceptible to cankers and the alder lace bug, but neither seem to be serious pests in our climate.
Bearberry or Kinnikinick
Arctostaphylos uva-ursi
Plant Description
Arctostaphylos uva-ursi, or Bearberry or Kinnikinick, is a low growing evergreen shrub. It grows no higher than 12 inches, and usually much lower to the ground. It can spread upwards of ten feet, though it will take a long time to get there. It is very cold hardy and very tolerant of poor soil and dry conditions. Once it is established do not disturb its roots.
The small leaf is 1/4 inch to 1 1/4 inches long, glabrous and obovate in shape. The leaves are an attractive dark and rich green color on the top of the leaf and a lighter and duller green beneath. They are arranged alternately on the stem. In fall the leaves can turn a bronze color, though I have rarely seen them do so in our climate.
In the spring, clusters of small white flowers with pink highlights form in small hanging racemes. The flowers have an interesting urn shape, but they are usually lost in the foliage. By the end of summer, 1/4 inch diameter red fruit forms on the bush. The fruits are not as showy as Cotoneaster apiculatus, but provide decent fall and winter interest.
Landscape Use
Bearberry should be kept out of full sun in our climates to prevent leaf scorch or leaf spot. It is particularly difficult to transplant, but worth the effort once established.
Points of Interest
It is an excellent choice for a groundcover, creating an attractive and dense low green carpet. It will trail gracefully over walls or rocks. It is tolerant of salt, making it a suitable location for placing next to walks or roads. I have not seen it regularly used in parking lot islands, but suspect that it would perform well in that location.
Notable Cultivars
Massachusetts One of the most readily available commercial cultivars, Massachusetts has smaller and darker leaves than the regular variety.
Big Sagebrush
Artemisia tridentata
Plant Description
Artemisia tridentata, or Big Sagebrush, is a native evergreen shrub that can vary widely in size and form. Most Big Sagebrush grows to be 2-6 feet high, but it can reach as much as 10 feet high. It has a loosely rounded form, but has an irregular outline. It is extremely drought tolerant and performs best in poor soil that are well-drained.
The leaf is gray green in color and has a spatulate shape with the tip of the leaf having three lobes, creating the look that the leaf has toes. The leaf is pubescent. In the fall clusters of yellow flowers emerge on stalks. They are noticeable, but not particularly attractive. The bark is a gray color and exfoliates in long strips. New growth is pubescent, giving it a silvery sheen.
Landscape Use
Not suited to use in most landscapes, it is ideal for naturalized landscapes or in very dry conditions. It should not be used near structures as the leaves have a high oil content and so pose a fire hazard.
Water Birch
Betula occidentalis
Plant Description
Betula occidentalis, or Water Birch, is a small to medium-sized multi-stemmed tree. It naturally occurs along streams and other bodies of water where it has ample amounts of water. It appears to tolerate drier conditions quite well though, as I have seen it thriving in several hot locations with poor soil. It is similar in appearance to Betula nigra, and it can be difficult to tell the two apart, especially when young. It grows 20-30 feet high and has a slightly pendulous habit and branches low to the ground.
The bark is a glossy reddish-brown color with prominent horizontal lenticels. The bark of Water Birch is typically darker than that of River Birch, and does not exhibit any exfoliating feature. Two inch long catkins form on the tree by late spring.
The leaves are 1-2 inches long and have a rounded triangular shaped. They are shorter and stouter than the leaves of Betula nigra. The leaves have a single or doubly-serrated margin. The leaf is a dull, but dark green color and slightly glabrous. In the fall the leaves turn a yellow color. Leaves are arranged alternately on the stem.
Landscape Use
Betula occidentalis is an underutilized plant in the landscape. Its slightly-weeping multi-stem form is attractive and the tree could be utilized in either a grouping or as a single specimen. It is also well suited to use in a naturalized landscape setting.
Because it branches low to the ground, it is not recommended for use close to walkways or streets, where its branches will interfere with traffic.
Rubber Rabbitbrush
Chrysothamnus nauseosus
Plant Description
Chrysothamnus nauseosus, or Rubber Rabbitbrush, is a drought tolerant shrub that grows 2-6 feet tall and equally as wide. It prefers full sun locations with well-drained soil. It grows quickly and is one of the first plants to establish itself on disturbed sites, such as gravel pits or construction zones.
The leaves are lanceolate to spatulate in shape and gray-green to pale-green in color. They are 1-4 inches long, arranged alternately on the stem, and have an entire margin. Clusters of small yellow tube flowers appear from summer to early fall. The flowers appear in a rounded corymb held slightly above the foliage. After the flowers fade they turn a light tan color, producing dry cloudy texture on top of the bush.
Landscape Use
Use in naturalized plantings or in dry areas. It is not the most attractive plant and should probably be used sparingly in most landscape settings.
Points of Interest
The bush takes its name from the strong (and not-so-pleasant) odor that is produced from its foliage and blossoms.
Russian Olive
Elaeaganus angustifolia
Plant Description
Eleganus angustifolia, or Russian Olive, is a small to medium (20-30 feet high and wide) sized shade tree that is very hardy and adaptable. It has a oval form that is often disrupted by bare spots left over from branch breakage. Young branches tend to have a modest weeping habit. It is extremely tolerant of soil conditions and moisture conditions. Russian Olive is a vigorous grower, capable of growing multiple feet a year for several years in succession. The bark is a gray-brown in color and has a rough texture and exfoliate in large, long strips. Vicious one inch or larger thorns can form on the branches.
The leaf is lanceolate in shape with and entire margin and light gray-green in color. It is arranged alternately on the stem and is 1-3 inches long. The gray color is excellent and makes the tree stand out in the landscape, while the small leaves give the tree a light and airy texture.
Small white and yellow tubular flowers bloom prolifically on the tree in the late spring or early summer. They have a very strong and attractive fragrance. Following the blossoms, small 1/2 inch long ovular fruit forms on the tree. The fruit is a dull green color that blends in with the leaves, making the fruit imperceptible unless viewed up close.
Landscape Use
Eleganus angustifolia is a good tree for difficult locations, either wet or dry. I have seen it used as an attractive lawn tree or shade tree, but unless properly pruned and cared for they tend to become ragged in appearance.
It is also a good selection as an accent plant, thanks to its distinct gray foliage that sets it apart from other trees around it.
Points of Interest
he fruit is sweet and edible. It suffers from a handful of diseases, most noted being stem canker and leaf wilt.
Due to its vigorous nature and tendency to spread it has been declared a noxious weed in several states and some counties in Southern Utah - so it should be used sparingly in locations where it is least likely to escape into the native landscapes.
Quaking Aspen
Populus tremuloides
Plant Description
Populus tremuloides, or Quaking Aspen, is a medium to large sized tree with an upright growth habit. It is native to the higher altitudes of the region, growing on the mountainsides in large colonies. It can grow 40-50 feet high and 20-30 feet wide. It prefers moister conditions in a sunny location, but is fairly adaptable to drier locations. The bark is a gray-white color that can approach the white color of Betula pendula as the tree ages. Fully mature trees will have furrowed and darker brown bark.
The leaves are 1 1/2 - 3 inches long and wide, being ovate in shape, tapering to a point and having an undulately serrated margin. The leaf is arranged alternately on the stem. It is a dark green color on the top of the leaf and a light green color on the bottom. When the wind blows it creates a quaking effect in the tree, causing the leaves to rotate on their petioles, which creates a shimmering effect as the leaf alternates between the dark and pale sides being visible. In the fall the foliage turns a deep and rich yellow color.
Landscape Use
Plant the tree in clumps, or plan on it forming into clumps. It is a very popular tree in high altitude landscapes where it is one of the few trees that will truly thrive. It can be used as an ornamental or shade tree.
Points of Interest
Quaking Aspen spreads rapidly and continually by sending up suckers. By doing this, a massive grouping of trees can be connected to the same root system.
It is very susceptible to borers, and the trees should be constantly monitored for any sign of damage. It is best to keep the tree healthy to avoid a potential infection.
Notable Cultivars
Populus tremula - Erecta: This very narrow tree grows 40 feet tall but only 8-12 feet wide. The margin of the leaf is noticeably more undulate than Quaking Aspen, and the fall color is a mixture of oranges and yellows.
Common Chokecherry
Prunus virginiana
Plant Description
Prunus virginiana, or Chokecherry, is a small flowering and fruiting tree, growing 20-30 feet high and 15-25 feet wide. It may natively occur as a large shrub or multi stem tree, but the tree form is readily available in commerce across the western United States. The canopy of the tree is open and airy until it is quite mature, when it finally fills in densely. The bark is a gray-brown color and has prominent horizontal lenticels. The color of the bark darkens and becomes furrowed as it matures.
The tree is quite a color changer, seemingly constantly changing color from spring through summer. In the spring, long racemes of white flowers (similar in form to a bottle-brush) cover the tree. Each small flower is only 1/4 inch wide and have 5 petals. Green leaves begin to emerge during the flowering period. On the most popular cultivar, Canada Red, the leaves turn a dark purple color by summer time, while new growth continues to emerge green before turning purple. Finally, in the fall the leaves turn a bright orange color.
Each leaf is 1 - 5 inches long and and elliptic or obovate in shape, with an acuminate tip. The margin of the leaf is finely serrated, and the veins are arranged in a pinnate pattern. During the summer, the tree produces large quantities of small, purplish-black fruit, 1/3 inch in diameter. The fruit is sour, but is popular for use in jams, jellies and syrups. Typically the birds will pick a tree clean before fall.
By summer, the 2 inch chestnuts begin to form on the tree, encased in a green, spiky capsule. In the fall, the capsule turns brown and splits open to release the hard, reddish-brown seed. Th spent seed capsules become messy once they fall on the ground.
Landscape Use
Use as an accent tree for its multi-season interest, or in massings. Its low branching habit makes it less-suited for use as a parking strip tree.
Points of Interest
Suckering at the base of the tree can be a problem if it is in tree form.
Notable Cultivars
Canada Red: The most popular variety, it grows 20-25 feet tall with purple foliage throughout most of the summer. New foliage emerges green.
Gambel Oak
Quercus gambelii
Plant Description
Quercus gambelii, or Gambel Oak, is a large shrub or small multi-stemmed tree, growing 10-25 feet tall and somewhat narrower in width. It has an irregular form with a dense branching and irregular habit. It is tolerant of dry soils and hot sunny locations. The stem is gray-brown and color with deep ridges and furrows.
The leaf is 3-6 inches long, obovate in shape and has 5-9 deep and irregular lobes. The leaves are arranged alternately or sub-oppositely on the stem and have a thick leathery feel. It is a dark glossy green color on the top, and often pale and pubescent below. The leaves turn a bright yellow, orange or red in the fall.
Large amounts of small catkins form on new growth in the spring. The catkins can make the edges of the tree appear to be covered with a moss. Elongated green acorns form over the summer before turning a pale brown color in fall and dropping from the tree. One half to two-thirds of the acorn is covered by the involucre.
Landscape Use
Use in drought-tolerant areas and in naturalized landscapes. It provides an impressive fall color display that looks especially good in masses.
Fragrant Sumac
Rhus aromatica
Plant Description
Rhus aromatica, or Oak Brush or Fragrant Sumac, is a hardy and fast-growing low-growing deciduous shrub. It grows 2-6 feet tall and spreads up to 10 feet wide. The spreading branches grow low to the ground and arch up slightly at the ends. It is tolerant of almost any setting that it is used in regardless of soil or moisture conditions. It prefers to grow in full sun but will also grow in almost complete shade.
The 2-5 inch long leaves are trifoliate, being composed of three separate leaflets. Each leaflet is ovate in shape with an irregularly rounded-toothed margin. The leaves are a glabrous dark green on the top, and mildly pubescent on the underside. In the fall the leaves turn a brilliant mixture of oranges and dark reds. The leaves have a fragrant odor, particularly noticeable when crushed.
Small yellowish catkins form on the plant in the early spring. The catkins on the male plant are slightly longer than those on the female plant. Female plants produce small and pubescent red drupe fruits that will persist on the plant into winter.
Landscape Use
Use it as a ground cover in dry locations such as rock gardens or on steep slopes. It is especially useful for soil stabilization along slopes.
Points of Interest
Use it as a ground cover in dry locations such as rock gardens or on steep slopes. It is especially useful for soil stabilization along slopes.
Notable Cultivars
Gro-low: The most widely available cultivar of the species. It is not as vigorous of a spreader as other Sumac. The fall color is exceptional.
Rhus trilobata - Oak Brush or Skunkbush Sumac: Very closely related to Rhus aromatica. It has slightly smaller leaves, but they are very pungent and have a strong foul odor.
Golden Currant
Ribes aureum
Plant Description
Ribes aureum, or Golden Currant, is a medium to large shrub that can grow between 6-12 feet tall with a variable width. It has an irregular growth habit with a poor ornamental form. The bark is grayish-brown in color and can have red overtones, with limited pubescence on young stems. It prefers well-drained soils, with little requirement for regular moisture.
The leaf is 1/2 - 1 inch long and has three to five lobes, with the ends of the lobes having a couple large rounded teeth. It is a light to medium green color and glabrous. The leaves are arranged alternately on the stem. In the fall the foliage turns a yellow, orange or red color.
In the spring to early summer, small racemes of yellow flowers appear. The flowers smell strongly of clove spice. Following the flowers, great amounts small rounded fruit, 1/4 - 1/2 in diameter, forms on the shrub. The fruit transitions through yellow and red colors before ripening to purplish-black color. The fruit is edible.
Landscape Use
Ribes aureum is more slightly more drought tolerant than Ribes alpinum, but its poor form makes it an inferior selection in most instances. The fruit is probably the best ornamental feature of the plant. Use it in a naturalized setting or particularly dry locations. Mass plantings help to hide the poor form of individual plants.
Points of Interest
Golden Currant is an attractive species to wildlife, who readily feast on the fruit.
Common Snowberry
Symphoricarpos albus
Plant Description
Symphoricarpos albus, or Common Snowberry, is a medium sized and fast-growing deciduous shrub reaching 3-6 feet tall and typically slightly narrower. It has a dense branching habit and a good upright, rounded form. It is extremely tolerant of all soil types and prefers full sun to almost full shade. It needs a moderate amount of moisture, but will tolerate dry conditions. The stem has a hollow or excavated pith and the bark is brown. New stems are pubescent.
The leaf is an attractive bluish-green color and oval to elliptic in shape. They are 3/4 - 2 inches long and often have an undulating or loosely lobed margin. New leaves have a distinct pink-tinged margin. The underside of the leaf is pubescent. In the early summer, small and drooping pink flowers appear in short terminal racemes. They are not ornamentally important, but are attractive when viewed closely.
Following the flowers, tight clusters of pure white fruits appear on the tree. The rounded drupe fruits create a unique color and texture and are an important ornamental feature. The fruit will persist on the tree into winter, but usually turns an unimpressive brown.
Landscape Use
Snowberry is good to use as a loose hedge plant or as a late-season accent plant. It is valuable for being a drought-tolerant shrub that can tolerate almost full shade.
Points of Interest
The berries are bland and inedible for humans, but wildlife will eat them. The berries are susceptible to berry rot, which causes them to turn brown towards the end of the season.
Notable Cultivars
Symphoricarpos x doorenbosii ‘Marleen’: Coral Berry, the fruit is a vibrant pink color.
