Recommended Shade Trees for the Community Garden Site

A Report via Noah McVay, RVACG Curator, from Dr. Donita Cartmill, Ph.D., to the Landscape Planning Committee

DECEMBER 23, 2016River Valley Area Community Gardens, IncorporatedPost Office Box 611, Spring Green, Wisconsin 53588

Executive Summary

A request for a list of recommended shade trees that would perform well on an open site in Sparta variant loamy sand (a well-drained, slightly acidic soil with a pH of 6.5 to 6.8 that experiences a high-water table), with – ideally – increased disease and pest resistance, was submitted by the Curator to the consultant.

The following report is the result of such a request.

About the Consultant

Donita Cartmill is an Associate Professor of Environmental Horticulture in the University of Wisconsin-Platteville School of Agriculture. Her research interests include nursery production practices, landscape establishment of woody ornamentals, and sustainable horticultural practices. Alongside her coursework, Donita is the Superintendent of Mansel and Dottie Johns Pioneer Gardens and a faculty adviser to The Horticulture Club at UW-Platteville, as well as the Education Liaison for the Wisconsin Arborists Association.

Curriculum Vitae

Doctor of Philosophy, Texas A&M University

Master of Science, Texas A&M University

Bachelor of Science, Stephen F. Austin State University

Professional Affiliations

Wisconsin Arborists Association

Wisconsin Nursery Association-Wisconsin Green Industry

International Society of Arboriculture

American Society for Horticultural Science

Awards

Outstanding Faculty Member, School of Agriculture, University of Wisconsin-Platteville (2014)

Teaching Award of Merit, North American Colleges & Teachers of Agriculture, SOA, BILSA (2013)

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Recommendations

Abies concolor | Concolor fir, white fir

Culture

Best grown in rich, medium moisture, slightly acidic, sandy/gravelly, well-drained soils in full sun to part shade. Best in full sun. Established trees tolerate some soil dryness, but best performance usually comes with moist soils. Trees generally grow poorly in heavy clay soils. This tree thrives in areas with long winters followed by cool summer climates, and it performs well in Southern Wisconsin. It is widely considered to be the best of the firs for tolerating the growing conditions of the Midwest.

Noteworthy Characteristics

Abies concolor, commonly called white fir or concolor fir, is primarily native to mountain slopes (3000-9000 feet in elevation) in the western U.S., including the southern Cascades and Sierras from Oregon to southern California and the Rockies from southern Idaho to Arizona and New Mexico. In the wild, it typically grows to 80-130’ tall, but on residential landscapes in the Midwest will more typically grow to 40-70’ tall with a spread to 20-30’. This is a narrow conical conifer with a straight trunk, spire-like crown and branching to the base. Upper branches tend to grow upward, but the lower branches tend to recline. With age, crowns flatten and lower branching begins to disappear. Soft, flattened, pale blue-green needles (to 2 1/2” long) have uniform coloration on both surfaces (the specific epithet is in reference to this). Slightly barrel-shaped cones (to 3-6” long) are most often yellowish-green, maturing to brown or purple. As is distinctive with the firs, the cones appear upright on the branches. Trees may not produce cones and seeds for up to the first 40 years. Bark is ash-gray and smooth, but will furrow with age.

The generic name is in reference to the ancient Latin word for spruce, a name first coined by Pliny around 77 C.E., whereas the specific epithet – again in Latin – means “the same color throughout.”

Problems

No serious insect or disease problems. Insect pests include balsam woolly adelgid, bark beetles, spruce budworms, aphids, bagworms and scale. Spider mites may occur in hot conditions. Disease problems include root rot, needle rust and twig blight. Trees are generally intolerant of urban pollution. Broken branches often become sites for fungal infections. Strong winds may damage taller trees.

Garden Uses

Large specimen fir for the landscape.

Fig. 1. From left to right: needles, cones, bark, and habit of A. concolor.

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Acer rubrum | Red maple

Culture

Easily grown in average, medium to wet, well-drained soil in full sun to part shade. Tolerant of a wide range of soils, but prefers moist, slightly acid conditions. Very cold hardy.

Noteworthy Characteristics

Acer rubrum, commonly called red maple, is a medium-sized, deciduous tree that is native to Eastern North America from Quebec to Minnesota south to Florida and eastern Texas. It typically grows 40-60’ tall with a rounded to oval crown. It grows faster than Norway and sugar maples, but slower than silver maple. In northern states, red maple usually occurs in wet bottomland, river flood plains and wet woods, but it can also be found in drier, rocky upland areas. Emerging new growth leaves, leafstalks, twigs, flowers, fruit and fall color are red or tinged with red. Quality of red fall color on species plants is variable. Leaves (to 2-5" long) have 3 principal triangular lobes (sometimes 5 lobes with the two lower lobes being largely suppressed). Lobes have toothed margins and pointed tips. Leaves are medium to dark green above and gray green below. Flowers on a given tree are primarily male or female or monoecious and appear in late winter to early spring (March-April) before the leaves. Fruit is a two-winged samara.

The generic name is Latin for “maple.” The specific epithet of rubrum (Latin for “red”) is everywhere in evidence: red flowers in dense clusters in late March to early April (before the leaves appear), red fruit (initially reddish, two-winged samara), reddish stems and twigs, red buds, and, in the fall, excellent orange-red foliage color.

Problems

No serious insect or disease problems. Watch for aphids, leafhoppers, borers, scale and caterpillars. Verticillium wilt attacks the vascular system and can be fatal. Canker, fungal leaf spot and root rots may also occur. Wind and ice may break some branches. Leaf hoppers can cause substantial damage.

Garden Uses

Plant as a specimen tree for the lawn, street or park. It is of note that this tree has a shallow, flattened root system that may buckle nearby sidewalks or driveways if planted too close.

Fig. 2. From left to right: flowers, samaras, foliage, and habit of A. rubrum.

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Amelanchier arborea | Downy serviceberry

Culture

Easily grown in average, medium, well-drained soil in full sun to part shade. Tolerant of a somewhat wide range of soils. Root suckers are common, and if not removed, will result in a shrubby growth habit for the plant.

Noteworthy Characteristics

Amelanchier arborea, commonly called downy serviceberry, is a deciduous, early-flowering, large shrub or small tree which typically grows 15-25' tall in cultivation but can reach 40' in the wild. A Wisconsin native plant that occurs most often in open rocky woods, wooded slopes, and bluffs. Features 5-petaled, showy, slightly fragrant, white flowers in drooping clusters which appear before the leaves emerge in early spring. The finely-toothed, obovate leaves exhibit good fall color. Flowers give way to small, round green berries which turn red and finally mature to a dark purplish-black in early summer. Edible pomes resemble blueberries in size and color and are often used in jams, jellies and pies. Amelanchier are commonly called Juneberries.

The generic name comes from a French provincial name for Amelanchier ovalis, a European plant in this genus, whereas the specific epithet is Latin for “growing in a tree-like manner.”

Problems

No serious problems. Rust, leaf spot, fire blight and powdery mildew are occasional disease problems, and sawfly, leaf miner, borers, and scale are occasional insect pests.

Garden Uses

Best in shrub borders, or in woodland, naturalized or native plant gardens, especially with dark or shaded backdrops which tend to highlight the form, flowers and fall color of the plant. Also effective along stream banks and ponds.

Fig. 3. From left to right: flowers, fruit, autumn foliage and habit of A. arborea.

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Amelanchier canadensis | Juneberry, shadblow, shadblow serviceberry

Culture

Easily grown in average, medium, well-drained soil in full sun to part shade. Tolerant of a somewhat wide range of soils.

Noteworthy Characteristics

A. canadensis, commonly called shadblow serviceberry, is a native deciduous, early-flowering, large shrub or small tree which typically grows 15-30' tall. Features showy, five-petaled, slightly fragrant, white flowers in drooping clusters which appear before the leaves emerge in early spring. Finely toothed, elliptic, medium to dark green leaves (1-3" long) change to orange-red in autumn. Flowers give way to small, round, green berries which turn red and finally mature to a dark purplish-black in early summer. Edible pomes resemble blueberries in size and color and are used in jams, jellies and pies.

The generic name comes from a French provincial name for Amelanchier ovalis, a European plant in this genus, whereas the specific epithet is Latin “from Canada,” which is part of the native range of this plant.

Problems

No serious insect or disease problems. Rust, leaf spot, blight and powdery mildew are sometime disease problems, and sawfly, leaf miner, borers and scale are sometime insect pests.

Garden Uses

Best in woodland, naturalized or native plant gardens, especially with dark or shaded backdrops which tend to highlight the form, flowers and fall color of the plant. Also effective along stream banks and ponds.

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Fig. 4. From upper left to right, and lower left: flowers, fruit, foliage, and habit of A. canadensis.

Betula nigra | River birch

Culture

Easily grown average, medium to wet soils in full sun to part shade. River birch is perhaps the most culturally adaptable and heat tolerant of the birches. Prefers moist, acidic, fertile soils including semi-aquatic conditions, but also tolerates drier soils. Consider using soaker hoses and bark mulches to keep the root zones cool and moist. Adapts well to heavy clay soils of Missouri and will tolerate poor drainage. Avoid pruning in spring when the sap is running.

Noteworthy Characteristics

Betula nigra, commonly called river birch, is a vigorous, fast-growing, medium-sized, Missouri native deciduous tree which occurs on floodplains, swampy bottomlands and along streams throughout the State. In cultivation, it can be trained as either a single trunk or multi-trunked tree. As a single trunk tree, it develops a pyramidal habit when young, but matures to a more rounded shape typically growing 40-70' tall. Multi-trunked trees form a more irregular crown and are generally considered to be the superior growth habit for this species. Salmon-pink to reddish brown bark exfoliates to reveal lighter inner bark. Leathery, diamond-shaped, medium to dark green leaves (1.5-3.5" long) with doubly toothed margins turn yellow in fall. Monoecious flowers appear in drooping, brownish male catkins and smaller, upright, greenish female catkins.

Generic name comes from the Latin name for birch, whereas the specific epithet means “black,” again in Latin.

Problems

One of the most disease-free birches. Most species of birch grow best in cool, northern climates, but do not adapt well to the hot summers of USDA Zones 5-9 and can be short-lived therein. Weakened birches become vulnerable to the bronze birch borer which typically infects and kills birches stressed by summer heat and humidity. River birches are Wisconsin natives that are naturally adapted to the climate and are extremely resistant to birch borer. Although river birches have some susceptibility to aphids, leaf miner and iron chlorosis in high pH soils, these problems are somewhat minor in comparison to the birch borer.

'Heritage' is a very popular river birch cultivar with superior ornamental features to the species.

Garden Uses

Specimen or small groupings for lawns, parks and commercial properties, and, in particular, for wet soils along ponds, streams or in low spots. Generally, a good substitute for the paper birch in the hot and humid areas of USDA Zones 5-9.

Fig. 5. From left to right: catkins, foliage, bark, and habit of B. nigra.

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Cercis canadensis | Eastern redbud

Culture

Easily grown in average, medium moisture, well-drained soils in full sun to part shade. Part shade is best in hot summer climates. Performs best in moderately fertile soils with regular and consistent moisture. Avoid wet or poorly drained soils. Since this tree does not transplant well, it should be planted when young and left undisturbed.

Noteworthy Characteristics

Cercis canadensis, commonly called eastern redbud, is a deciduous, often multi-trunked understory tree with a rounded crown that typically matures to 20-30’ tall with a slightly larger spread. It is particularly noted for its stunning pea-like rose-purple flowers which bloom profusely on bare branches in early spring (March-April) before the foliage emerges. This tree is native to eastern and central North America from Connecticut to New York to southern Ontario and the Great Lakes south to Western Texas and Florida. It is found in open woodlands, thickets, woodland margins, limestone glades and along rocky streams and bluffs throughout its distribution. Flowers (to ½” wide) bloom in clusters of 4-10. Flowers are followed by flattened leguminous bean-like dry seedpods (to 2-4” long) that mature to brown in summer. Each pod has 6-12 seeds. Pods may remain on the tree into winter. Alternate, simple, cordate, broadly ovate to nearly orbicular, dull green to blue-green leaves (3-5” across) have a papery texture and are short pointed at the tip. Leaves turn pale yellow to greenish-yellow in fall. Cercis canadensis is the state tree of Oklahoma.

Generic name comes from the Greek word kerkis, meaning “weaver’s shuttle” in reference to the resemblance of each seed pod to a weaver’s shuttle, whereas the specific epithet is in reference to Canada (southern Ontario being part of the native range of this tree).

Problems

Canker can be a significant disease problem. Verticillium wilt, dieback, leaf spots, mildew and blights may also occur. Insect pests include Japanese beetles, tree hoppers, leaf hoppers, caterpillars, borers, webworms and scale. Keeping the tree vigorous by regular watering and fertilization and by pruning out dead branches as needed will help keep the tree healthy.

Garden Uses

Specimen or small groups. Lawns, shrub borders, woodland margins, or along patios. Street tree or lawn tree. Attractive in naturalized settings.

Fig. 6. From left to right: flowers, legumes, foliage and habit of C. canadensis.

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Chionanthus virginicus | Fringetree

Culture

Easily grown in average, medium, well-drained soil in full sun to part shade. Prefers moist, fertile soils. Seldom needs pruning. Tolerant of air pollution and adapts well to urban settings. Intolerant of prolonged dry conditions.

Noteworthy Characteristics

Chionanthus virginicus, commonly called fringetree, is a deciduous, Missouri native shrub or small tree with a spreading, rounded habit that typically grows 12-20' tall (to 35' in the wild, however) and most often occurs in rich, moist woods and hillsides, moist stream banks, limestone glade margins and rocky bluffs and ledges. Common name refers to the slightly fragrant, spring-blooming flowers which feature airy, terminal, drooping clusters (4-6" long) of fringe-like, creamy white petals. Dioecious (separate male and female plants), but also may have perfect flowers on each plant. Male flowers are showier than female flowers. Fertilized perfect or female flowers give way to clusters of olive-like fruits which ripen to a dark, bluish black in late summer and are a food source for birds and wildlife. Wide, spear-shaped leaves (to 8" long) turn yellow in autumn.

The generic name comes from the Greek words chion meaning “snow” and anthos meaning “a flower.” Both Greek words refer to the snow-white flowers of C. virginicus, whereas the specific epithet refers to the Latin form of Virginia.

Problems

No serious insect or disease problems. Some susceptibility to scale and borers (particularly when grown in dry locations).

Garden Uses

Grow in groups or as specimens in lawns or in shrub or woodland borders. Also may be used in native plant gardens or near streams or ponds. Can be spectacular in full bloom.

Fig. 7. From left to right: flowers, drupes, foliage, and habit of C. virginicus.

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Crataegus crus-galli var. inermis | Thornless cockspur hawthorn

Culture

Grow in average, medium moisture, well-drained soils in full sun. Tolerates a wide range of soils as long as drainage is good. Tolerates light shade and some drought. Tolerates many urban pollutants.

Noteworthy Characteristics

Crataegus crus-galli, commonly called cockspur thorn, is sometimes seen as a dense, low-branched, broad-rounded tree to 25-35’ with horizontal branching armed with numerous large thorns (1.5-3” long). Lower branches often sweep near to the ground. It is also often seen as a tall, flat-topped shrub. It is native from Quebec to North Carolina and Kansas. Obovate to oblong-obovate dark green leaves (to 3” long) have wedge-shaped bases. Foliage turns orange to scarlet to purple red in fall. White flowers (in corymbs to 3”) bloom in May for a period of 7-10 days. Flowers emit an unpleasant fragrance. Flowers are followed by rounded fruits (3/8” diameter) that ripen to deep red in fall (September-October) and typically persist to late fall. Fruits are technically edible, but are usually best left for the birds. The fruit is sometimes called a haw.

The generic name comes from the Greek word kratos, indicating the inherent strength within its strong, hard wood, whereas the Latin phrase crus-galli means “leg of a cock” in reference to the purported resemblance of the plant’s thorns to a cock’s spurs.

Problems

Pests and diseases are a problem with most hawthorns. Plants are susceptible to cedar-hawthorn and cedar-quince rusts (rust stage where eastern red cedars are present in the area) and fireblight. Other potential diseases include fungal leaf spots, powdery mildew, cankers, apple scab, leaf blight and twig blight. Potential insect pests include aphids, borers, caterpillars, lacebugs, leafminers and scale. Red spider mites may also occur. Use of pesticide sprays may be advisable in areas where this plant suffers from significant diseases and insects. On species plants, numerous thorns pose significant risks for young children and also make culture/pruning more difficult.

Garden Uses

Small flowering landscape tree for lawns or open woodland areas. Notwithstanding disease susceptibility, a well-maintained tree can be ornamentally attractive. On species plants, thorns are a drawback for pedestrian areas or areas with small children. Plants may be effective when grown as barrier plants on property borders or in hedgerows.

Fig. 8. From left to right: flowers, pomes, foliage, and habit of C. crus-galli var. inermis.

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Ginkgo biloba | Ginkgo, maidenhair tree

Culture

Easily grown in average, medium moisture soil in full sun. Prefers moist, sandy, well-drained soils. Tolerant of a wide range of soil conditions, including both alkaline and acidic soils and compacted soils. Also tolerant of saline conditions, air pollution and heat. Adapts well to most urban environments.

Noteworthy Characteristics

Ginkgo biloba is a deciduous conifer (a true gymnosperm) that matures to 100' tall and enjoys a lifespan often exceeding a millenia. It is the only surviving member of a group of ancient plants believed to have inhabited the earth for the last 190 million years. It features distinctive two-lobed, somewhat leathery, dichotomous (i.e., fan-shaped), rich green leaves with diverging (almost parallel) veins. Leaves turn bright yellow in fall. Ginkgo trees are commonly called maidenhair trees in reference to the resemblance of their fan-shaped leaves to maidenhair fern leaflets (pinnae). Ginkgo is a dioecious species (separate male and female trees). Nurseries typically sell only male trees (fruitless), because female trees produce seeds encased in fleshy, fruit-like coverings which, at maturity in autumn, are messy and emit a noxious, foul odor upon falling to the ground and splitting open.

The generic name is a misconstruction from the 17th century of the Japanese word ginkyo, or “silver apricot,” whereas the specific epithet – meaning “two-lobed” in Latin – is in direct reference to the dichotomous morphology of the leaves.

Problems

No serious insect or disease problems. Usually slow growing, with initial growth being somewhat sparse.

Garden Uses

Excellent selection for a variety of uses, including lawn tree, street tree or shade tree. Also effective in city parks or near commercial buildings.

Fig. 9. From upper left to upper right, and lower left to lower right: female flowers, male flowers, fruit, midsummer foliage, senescing autumn foliage, and habit of G. biloba.

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Gleditsia triacanthos var. inermis | Thornless honey-locust

Culture

Best grown in organically rich, moist, well-drained soils in full sun. Tolerant of a wide range of soils. Also tolerant of wind, high summer heat, drought and saline conditions.

Noteworthy Characteristics

Gleditsia triacanthos, commonly called honey locust, is native from Pennsylvania to Iowa south to Georgia and Texas. It typically grows 60-80’ (less frequently to 120’) tall with a rounded spreading crown. Trunk and branches have stout thorns (to 3” long) that are solitary or three-branched. Inconspicuous, greenish yellow to greenish white flowers appear in racemes in late spring. Flowers are followed by long, twisted and flattened, dark purplish-brown seedpods (to 18” long) which mature in late summer and persist well into winter. Seedpods contain, in addition to seeds, a sweet gummy substance that gives honey locust its common name. Species plants are generally not sold in commerce today because the thorns and seedpods are considered to be significant liabilities; thornless cultivars are preferred in cultivation.

The generic name honors Johann Gottlieb Gleditsch (1714-1786), director of the Botanical Garden, Berlin, whereas the specific epithet comes from the Greek words acantha (meaning “thorn”) and trios (meaning “three”), in reference to the three-branched thorns on species plants. The additional var., along with the Latin inermis indicates that specimens within the population (var. = variety) lack thorns (inermis means thornless).

Problems

Honey locust is susceptible to a large number of potential disease problems, including leaf spot, canker, witches’ broom, powdery mildew and rust. Borers and webworms are common insect problems in some areas. Leaflets are too small to rake, which is good, but seed pods are unattractive on the tree and messy when they fall. Thorns on species plants can be just plain nasty.

Garden Uses

The species form is not recommended for landscape usage due to its numerous thorns. Thornless/seedless varieties and cultivars are recommended for lawns and sometimes as street trees.

Fig. 10. From left to right: flowers, legumes, foliage and habit of G. triacanthos var. inermis.

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Metasequoia glyptostroboides | Dawn redwood

Culture

Best grown in moist, humusy, well-drained soils in full sun. Best foliage color is in full sun. Appreciates consistent moisture. Tolerates some wet soils.

Noteworthy Characteristics

Metasequoia glyptostroboides, commonly called dawn redwood, is a deciduous, coniferous tree that grows in a conical shape to 100’ tall. It is related to and closely resembles bald cypress (Taxodium ssp.), giant sequoia (Sequoiadendron giganteum) and redwood (Sequoia sempervirens). The fossil record suggests M. glyptostroboides has a geologic history of some 50 million years. However, it was not until 1941 that it was first discovered growing in the wild near the town of Modaoqi, China by Chinese forester, T. Kan. Seeds collected from the original site were made available to the Missouri Botanical Garden in 1947. Seedlings grown therefrom were planted in front of the Lehmann Building at Missouri Botanical Gardens in 1952 where they have now developed into large mature trees (70’+ tall). As the tree matures, the trunk broadens at the base and develops attractive and sometimes elaborate fluting. Bark on mature trees is often deeply fissured. It features linear, feathery, fern-like foliage that is soft to the touch. Foliage emerges light green in spring, matures to deep green in summer and turns red-bronze in fall. Trees are monoecious, producing oval, light brown female cones (3/4” long) and pendant globose male cones (1/2” long). The twigs, needles and cone scales are in opposite pairs.

Th generic name comes from the Greek words metra (meaning “with, after, sharing, or changed in nature”) and Sequoia (to which it is related and to which fossil specimens were first referred), whereas the specific epithet means “resembling the genus Glyptostrobus.”

Problems

No serious insect or disease problems.

Garden Uses

This is a large tree that needs a large space. Excellent landscape specimen or street tree. May be an effective container plant when small.

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Fig. 11. From upper left to upper right, and lower left to lower right: cones, summer foliage, autumn foliage, bark, and habit of M. glyptostroboides in summer and winter.

Ostrya virginiana | American hop hornbeam, ironwood

Culture

Easily grown in average, medium, well-drained soil in full sun to part shade.

Noteworthy Characteristics

Ostrya virginiana, commonly called American hop hornbeam, is a deciduous, Wisconsin native which usually occurs in dry soils on rocky slopes, upland woods and bluffs throughout the state. A small to medium-sized, understory tree with a generally rounded crown. Typically grows 25-40' tall with a slightly smaller spread. Features birch-like, oval to lance-shaped, sharply-serrated, dark yellowish-green leaves (to 5" long). Leaves turn an undistinguished yellow in autumn and often drop early. Flowers are monoecious (reddish-brown male flowers and greenish female flowers appear in separate catkins on the same tree). Flowers are not particularly showy, although the male catkins are more prominent and are present throughout winter. Female catkins are followed by drooping clusters of sac-like, seed-bearing pods which, as the common name suggests, somewhat resemble the fruit of hops. Also commonly called ironwood because of its extremely hard and dense wood.

The generic name originates form the Greek word ostrys, meaning “bone-like” (in reference to the tree’s dense, very hard wood), whereas the specific epithet – in Latin – means “of or from Virginia.” (Virginia is party of the natural range of this species.)

Problems

No serious insect or disease problems.

Garden Uses

Lawn tree, street tree or woodland garden.

Fig. 12. From left to right: catkins, nutlets, foliage, and habit of O. virginiana.

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Pinus nigra | Austrian pine, black pine

Culture

Grow in deep, moist, well-drained soils in full sun. Tolerates some drought once established. Also tolerates clay soils. Generally tolerant of urban conditions.

Noteworthy Characteristics

Pinus nigra is a medium to large conifer that is native from central and southeastern Europe to western Asia. It grows 40-60’ tall over time (less frequently to 100’). Trees exhibit a dense pyramidal habit in youth. Crown rounds with age forming a spreading flat top or dome. From an ornamental standpoint, older trees can be quite attractive, featuring dense spreading branching, stiff dark green needles (3-6” long) in bundles of two and plate-like, furrowed, dark brown to black bark. Oval, stalkless cones (to 3” long) mature to brown. Also commonly called European black pine.

The generic name comes from the Latin word pinus (meaning “pine”), whereas the specific epithet comes from the Latin word nigra (meaning “black”).

Problems

Notwithstanding the attributes of Austrian pine, its susceptibility to Sphaeropsis (Diplodia) tip blight, particularly in the Midwest, is of such significance that planting it in the City of Madison is not now recommended. Also susceptible to Dothistroma needle blight. Pine moth and pine wilt nematode may appear.

Garden Uses

Specimen, screen or windbreak. Susceptibility to diseases and insects limits use in some parts of the U. S. including the Midwest.

Fig. 13. From left to right: mature unopened cone and needles, as well as bark and habit, of P. nigra.

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Platanus occidentalis | Sycamore

Culture

Easily grown in average, medium to wet, well-drained soils in full sun. Tolerates light shade. Prefers rich, humusy, consistently moist soils. Generally tolerant of most urban pollutants.

Noteworthy Characteristics

Sycamore (American sycamore, eastern sycamore, buttonwood or buttonball tree) is generally regarded to be the most massive tree indigenous to eastern North America. It is a deciduous, usually single-trunk tree that typically grows to 75-100’ (less frequently to 150’) tall with horizontal branching and a rounded habit. Trunk diameter typically ranges from 3-8’, with some records up to 16’. Although the tulip tree (see Liriodendron tulipifera) may reach similar heights, its trunk diameters are generally smaller. Sycamore is native to lowland areas, typically reaching its largest size along streams, rivers and floodplains. It is commonly found throughout the river bottoms of southern Wisconsin. The signature ornamental feature of this huge tree is its brown bark which exfoliates in irregular pieces to reveal creamy white inner bark. Mature trees typically display mottled white bark that facilitates identification from great distances. The large 3-5 lobed medium to dark green leaves (4-10” wide) have coarse marginal teeth. In fall, foliage typically turns an undistinguished yellow-brown. Small, non-showy, monoecious flowers appear in small rounded clusters in April. Male flowers are yellowish and female flowers are reddish. Female flowers give way to fuzzy, long-stalked, spherical fruiting balls (to 1 3/8” diameter) that ripen to brown in October and persist into early winter. Each fruiting ball consists of numerous, densely-packed, tiny seed-like fruits (achenes). Fruiting balls gradually disintegrate as fall progresses, dispersing their seeds, often in downy tufts, with the wind. Wood has been commercially used for a variety of products including furniture, cabinets, barrels, crates and butcher blocks. Native Americans hollowed out trunk sections for dugout canoes. European settlers reportedly gave this tree the common name of sycamore because the foliage resembled the sycamore of the British Isles (Acer pseudoplatanus) which is actually a maple.

The generic name is derived from the Greek word platanos, meaning “flat,” whereas the specific epithet originates from the Latin word occidentalis – meaning “of the west.”

Problems

Sycamore anthracnose is a significant disease that can severely damage the foliage and twigs, often precipitating premature leaf drop. Canker, leaf spot and powdery mildew may also occur. Insect visitors include borers, scale, Japanese beetles, caterpillars and mites. When grown as a lawn tree, litter from twigs, large leaves, bark and fruiting balls can pose significant clean-up problems.

Garden Uses

A large tree for a large space. Generally considered too large and too messy for street tree use.

Fig. 14. From left to right: flower, fruit, foliage, bark and habit of P. occidentalis.

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Populus deltoides | Cottonwood, Eastern cottonwood

Culture

Easily grown in average, medium to wet, well-drained soils in full sun. Prefers consistently moist soils, but tolerates drought. Each tree develops an extensive root system, but no clones sprout up therefrom as in the case of aspens. Twigs that stick in the ground may sprout roots and grow.

Noteworthy Characteristics

Populus deltoides is a large, fast-growing, deciduous tree that typically grows 50-80’ (less frequently to 120’) tall with a broad, open-rounded shaped habit. Yellowish twigs, coarsely toothed leaves and gummy end buds distinguish this from the other poplars. It is native from eastern North America through the Great Plains, typically growing along streams and rivers and in lowland areas and swamps. Settlers who pushed westward into the Great Plains in the 1800s sometimes planted eastern cottonwoods along small streams and creeks. Tiny male and female flowers appear in separate catkins on separate male and female trees (dioecious). Flowers bloom in early spring (March-April) before the foliage emerges. Male flowers are reddish but not showy. Female flowers give way to dehiscent capsules that split open when ripe (May in St. Louis), broadcasting abundant densely-tufted seeds. Seeds with silky white hairs give the appearance of cotton as they blow through the air and along the ground, typically collecting along gutters, curbs, roadsides and fences. Bark on mature trees is ridged and dark gray. Triangular, acuminate, coarsely toothed, glossy dark green leaves (to 5” long). Leaves turn yellow in fall. Wood is weak and has little commercial value (warps easily) other than for crates, plywood and pulp.

The generic name refers to the fact the species is a member of the poplar family, whereas the specific epithet is in reference to the triangular or “deltoid” shape of the leaves.

Problems

Susceptible to a wide range of diseases including dieback, cankers, leaf spots, rusts and powdery mildew. Insect visitors include borers, aphids, caterpillars and scale.

Garden Uses

Generally considered inappropriate for ornamental use. A particularly poor selection for urban areas because trees are messy, weak-wooded and their roots can buckle sidewalks and damage sewer lines. May be effectively grown in rural areas in low-spots or along streams where other large trees may not flourish. Some all-male cultivars are available in commerce (no cotton to clean up).

Fig. 15. From left to right: catkins (female and male), seed heads, foliage, bark, and habit of P. deltoides.

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Quercus alba | White oak

Culture

Best grown in rich, moist, acidic, well-drained loams in full sun. Adapts to a wide variety of soil conditions with good drought tolerance.

Noteworthy Characteristics

White oak is a large deciduous Missouri native tree of the white oak group. It typically occurs in dry upland slopes and ledges as well as lowland valleys and ravines throughout the State. Grows to 50-80' tall in cultivation and taller (to 100') in the wild. Pyramidal when young, but matures into a substantial tree with a wide-spreading, rounded crown. Insignificant yellowish-green flowers in separate male and female catkins appear in spring shortly after the leaves emerge. Fruits are oval acorns (to 3/4" long) with warty-scaled cups. Leaves (4-9" long) have 7 to 9 deep rounded lobes. Leaves emerge pinkish in spring, but mature to dark green. Variable fall color ranges from uninteresting browns to quality shades of dark red. White oak grows over much of eastern North America and is an important hardwood timber tree. Widely used in landscapes, but slow growth rate and large size has somewhat tempered its popularity.

The generic name originates from the Latin work for oak, quercus, whereas the specific epithet alba, Latin for “white,” refers to the light ash-gray bark.

White oak is the Illinois State Tree.

Problems

Potential diseases include oak wilt, anthracnose and oak leaf blister. Potential insects include scale, oak skeletonizer, leaf miner and lace bug.

Garden Uses

Large shade tree, street tree or lawn tree. Needs a large space in which to grow.

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Fig. 16. From upper left to right, and lower left to lower right: flowers, acorns, foliage, autumn foliage, and habit of Q. alba.

Quercus bicolor | Swamp white oak

Culture

Easily grown in average, medium to wet, acidic soil in full sun.

Noteworthy Characteristics

Quercus bicolor is a medium sized, deciduous tree with a broad, rounded crown and a short trunk which typically grows at a moderate rate to a height of 50-60' (sometimes larger). Leaves are dark, shiny green above and silvery white beneath, with 5-10 rounded lobes or blunt teeth along the margins. Fall color is yellow, but sometimes reddish purple. Insignificant flowers in separate male and female catkins in spring. Fruits are acorns which mature in early fall. Indigenous to north, central and eastern Missouri in moist to swampy locations in bottomlands and lowlands, such as along streams and lakes, valleys, floodplains and at the edge of swamps. Also has surprisingly good drought resistance.

Problems

Generally a durable and long-lived tree, but is susceptible to a large number of potential diseases and insect pests, including anthracnose, canker, leaf spot, rust, blight, galls, caterpillars, borers, leaf miners, oak lace bug and oak mite. Chlorosis (yellowing of the leaves while the veins remain green) often occurs when soils are not properly acidic. Can be difficult to transplant and establish.

Garden Uses

Specimen, street tree, lawn tree. A good tree for wet ground and low spots.

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Fig. 17. From upper left to right, and lower left to lower right: catkins, acorns, foliage, bark and habit of Q. bicolor.

Quercus macrocarpa | Bur oak

Culture

Easily grown in average, dry to medium, well-drained soils in full sun. Prefers moist well-drained loams, but adapts to a wide range of soil conditions. Good drought tolerance. May take up to 35 years for this tree to bear a first crop of acorns.

Noteworthy Characteristics

Quercus macrocarpa is one of the most majestic of the native North American oaks. It is a medium to large sized deciduous oak of the white oak group that typically grows 60-80’ (less frequently to 150’) tall with a broad-spreading, rounded crown. Acorn cups are covered with a mossy scale or bur near the rim, hence the common names. It is native to a variety of habitats in central and eastern North America. Best growth occurs in bottomland soils, particularly in the Ohio River valley. In Wisconsin, it typically occurs on former prairies, along with upland forests. Insignificant monoecious yellowish-green flowers in separate male and female catkins appear in spring as the leaves emerge. Fruits are oval acorns (to 1 1/2” long), with fringed, burry cups that extend to approximately 1/2 to 3/4 the acorn length. Acorns are an important source of food for wildlife. Leathery, dark green leaves (6-12” long) with 5-9 rounded lobes are variable in shape, but usually have a pair of deep central sinuses that extend nearly to the midrib giving the leaf a waisted appearance. Fall color is an undistinguished yellow-brown. Twigs sometimes are ridged with corky wings.

The generic name originates from the Latin word for oak, quercus, whereas the specific epithet of macrocarpa originates from the Greek macros (meaning “large”) and carpa (meaning “fruit”), both in reference to the large size of the acorns.

Problems

Oaks are susceptible to a variety of diseases, including oak wilt, chestnut blight, shoestring root rot, anthracnose, oak leaf blister, cankers, leaf spots and powdery mildew. Potential insect pests include scale, oak skeletonizer, leaf miner, galls, oak lace bugs, borers, caterpillars and nut weevils. Notwithstanding the aforementioned, bur oak is generally considered to be a low-maintenance, long-lived tree.

Garden Uses

A large shade tree for very large lawns or parks.

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Fig. 18. From upper left to right, and lower left: catkins, acorns, foliage, bark, and habit of Q. macrocarpa.

Salix alba | White willow

Culture

Grow in average, medium to wet, well-drained soils in full sun to part shade. Thrives in moist soils. Prefers full sun. Prune as needed in late winter to early spring.

Noteworthy Characteristics

Salix alba, commonly called white willow, is native to Europe, central Asia and northern Africa. It was brought to the U.S. in the 1700s by European settlers and has since escaped and naturalized in many parts of North America. This is an upright, fast-growing, deciduous tree than grows to 50-80’ tall with erect branching that typically forms a broad, loose, open crown. Bark is yellowish-brown. The species is now rarely sold, but a number of cultivars are very popular, including plants noted for weeping form and for showy red or yellow winter twigs. This is a dioecious species, with flowering catkins appearing on separate male and female trees in May. Male catkins (to 2” long) are somewhat showy, having tiny flowers with yellowish anthers and two stamens. Female catkins are smaller and non-showy, with greenish flowers. Narrow, lanceolate, finely-toothed leaves (to 4” long) are gray-green above and white-silky beneath. Leaves gradually taper at the bases. Variable fall color is usually a pale yellow, but sometimes appears as a quality yellow.

The generic name originates form the Latin word salix (meaning “willow”), whereas the specific epithet of alba – from the Latin word for white – refers to the glaucous foliage.

Problems

Susceptible to numerous disease problems including blights, powdery mildew, leaf spots and cankers. It also is visited by many insect pests including aphids, scale, borers, lacebugs and caterpillars. Wood is weak and tends to crack. Branches may be damaged by ice and snow. Litter from leaves, twigs and branches may be a problem. Shallow roots may clog sewers or drains and make gardening underneath trees difficult.

Garden Uses

White willow is generally not recommended as a residential landscape tree. Regardless of availability, white willow may be an acceptable selection for areas with moist soils along streams, ponds or in low spots in the landscape where other shrubs or small trees may falter. Not recommended as a shade tree or street tree because of weak wood, insect/disease susceptibility, moisture-seeking roots and litter potential.

Fig. 19. From left to right: flowers, nutlets, foliage, and habit of S. alba.

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Conclusion

When determining the desired tree species for incorporation into the landscape, the Committee should ensure the aesthetics of the community garden site are being at least maintained, if not accentuated upon. Above all else, landscapes are to be of human interest – an imperative within a public facility such as a community garden site. However, other factors influencing cultivation, such as species functionality (ease of maintenance, edible fruits, etcetera), plant-soil interrelationships (required pH, soil texture, beneficial soil microorganisms), disease and pest resistance, and biodiversity of the artificial woodland in support of native flora and fauna, must be taken in account. Moreover, the appropriate players will have to ascertain the purpose of newly installed shade trees in the landscape, prioritize species selection, and draw up both short- and long-term strategies for their care.

Respectfully submitted,

Donita Cartmill, Ph.D.

Associate Professor of Environmental Horticulture

Pioneer Tower 312

School of Agriculture

University of Wisconsin-Platteville

1 University Plaza

Platteville, WI 53818

Via

Noah R. McVay

President and Curator

River Valley Area Community Gardens, Incorporated

Post Office Box 611

Spring Green, WI 53588

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