Rhus typhina, or staghorn sumac, is a native eastern North American shrub species that is fast-growing, drought-tolerant small tree generally free of pests and diseases. Native to eastern North America, it is found from southeastern Canada (Quebec, Ontario) to the northeastern and midwestern United States, extending south to Georgia, Indiana, and Iowa. Staghorn sumac can spread aggressively through suckers, forming colonies, making it a good candidate for erosion control, but less ideal for boulevards and yards.

CAUTION: INVASIVE TENDENCIES. Robinia pseudoacacia, or black locust, is native to Southern Appalachia with a range that extends from central Pennsylvania to northern Georgia and westward to Arkansas and Oklahoma. This species is not recommended to plant due to its invasive tendencies. It is well-adapted to poor quality soil and is often used in land reclamation projects. While the northern tip of its range is only a few hundred kilometers south of much of Canada, it is considered to have invasive tendencies due to its rapid spread through root sprouts and abundant seeds causing it to crowd out native plant species. The tree can break branches in high winds and feature small thorns. Black locust is in the pea family and its roots fix Nitrogen in the soil.

CAUTION: INVASIVE TENDENCIES. Salix alba, or white willow, is a non-native tree species, native to Europe and western and central Asia. It is a fast-growing tree highly tolerant of wet sites but has weak wood and is prone to storm damage. It features a shallow root system and is adaptable to various pH levels. Supplemental watering during dry periods and a layer of mulch can help moderate soil temperature and conserve moisture. It creates a litter of leaves, twigs, and branches, and its root system can disrupt drainage systems or concrete. White willow is best suited for larger landscapes. It is considered moderately messy due to the leaf drop and catkin litter.

Salix amygdaloides, or peachleaf willow, is native to central North America, with a range extending from the Great Lakes region to the eastern United States and much of southern Canada. It prefers moist, boggy, and neutral to acidic soil, located in full sun. Similar to other willows, this tree requires a significant amount of water for growth. It can protect river banks from erosion and is characterized as a short-lived, fast-growing tree. Like other native willows, peachleaf willow acts as a larval host for the mourning cloak and viceroy butterflies. Salix amygdaloides drops a significant number of leaves and catkins, with the heaviest shedding in the spring and is considered moderately messy.

Salix bebbiana, or bebb's willow, is a short-lived, fast-growing large native tree/shrub that is susceptible to insect and disease issues, as well as wind damage. Its range extends throughout much of Canada and the northern United States, from Alaska and Yukon south to California and Arizona and northeast to Newfoundland and New England. It prefers moist, well-drained soils, and full sun or partial shade environments. It serves as an important larval host for both mourning cloak and viceroy butterflies. Bebb's willow can be utilized for stream bank erosion control, protecting aquatic environments, enhancing wildlife habitats, and increasing biodiversity. Salix bebbiana drops a moderate number of leaves and catkins, with the heaviest shedding in the spring.

Salix discolor, or pussy willow, is a fast-growing short-lived tree/shrub native North America. It thrives in a variety of soil types, but prefers fertile, moist, well-drained soils, and is tolerant of wet conditions. Clipped branches in early spring are often used as a complement in cut floral displays. It is susceptible to insect and disease issues, as well as wind damage. Salix discolor drops a moderate number of leaves and catkins, with the heaviest shedding in the spring. It is considered moderately messy due to the leaf drop and catkin litter that require regular cleanup.

Salix lucida, or shining willow, is a native northern and western North America shrub that is brittle, fast-growing, and short-lived. Its native range is northern and western North America, occurring in wetland habitats from Alaska and Yukon Territory south to California and New Mexico, and east to eastern Saskatchewan. It prefers a damp heavy soil, but will survive in most soils. It is prone to disease and insect damage but is an important plant for wildlife and rangelands. Shining willow is recommended for restoration projects and is easily propagated. Salix lucida drops a moderate number of leaves and catkins, with the heaviest shedding in the spring.

Salix nigra, or black willow, is a native North American tree that is fast-growing, short-lived native tree with a shallow root system. It prefers moist to wet soils with good drainage, but can adapt to a variety of soil types, and naturally grows near water sources such as streams, rivers and wetlands. It plays a valuable role in preventing soil erosion and flood damage by binding soil banks. Black willow is generally not advised for residential landscapes due to its susceptibility to breakage, potential pest and disease issues, need for consistently moist soils, litter problems, and its mature size. Salix nigra drops a significant number of leaves and catkins, with the heaviest shedding in the spring. It is considered extremely messy due to the leaf drop and catkin litter that require regular cleanup.

Salix pentandra, or Laurel Willow, Bay Willow, Bayleaf Willow, is a non-native tree species, native to Europe and western and central Asia. It is a fast-growing tree highly tolerant of wet sites but has weak wood and is prone to storm damage. It features a shallow root system and is adaptable to various pH levels. Supplemental watering during dry periods and a layer of mulch can help moderate soil temperature and conserve moisture. It creates a litter of leaves, twigs, and branches, and its root system can disrupt drainage systems or concrete. White willow is best suited for larger landscapes. It is considered moderately messy due to the leaf drop and catkin litter.

Sassafras albidum, or sassafras, is a native North American tree belonging to the Laurel family, found throughout Eastern North America. It prefers moist, well-drained, acidic, loamy soils, but can tolerate dry and sandy soils, and even clay as long as it does not have poor drainage. It thrives in full sun to part shade, making it suitable for a variety of garden locations, including naturalized plantings, screens, or as a striking lawn specimen. Considered somewhat aggressive since it spreads through suckers quite readily. Sassafras is a hardy tree, adaptable to USDA Zones 4 to 9. In its native range, sassafras can be found in wood margins, thickets, roadsides, and fields in large colonies. Crushed leaves have a fragrant lemony scent. Sassafras is relatively free of insect and disease problems, although it can suffer from chlorosis in alkaline soils. It is also tolerant of deer, drought, and black walnut trees. Sassafras albidum drops a moderate number of leaves and small seed clusters, with the heaviest shedding in the fall.

Sequoiadendron giganteum, or sierra redwood, is a non-native tree species in Ontario that naturally grows only on the western slope of the Sierra Nevada range in California. It is a fast-growing tree suited only for very large properties due to rooting requirements. It prefers deep, well-drained acidic, loamy, wet, soils. It is generally intolerant of extreme temperatures. Sequoiadendron giganteum drops a moderate number of needles and small cones, with the heaviest shedding in the fall. It is considered moderately messy due to the needle drop and cone litter that require regular cleanup.

Sorbus alnifolia, or Korean mountain ash, is a non-native tree species originating from China, Korea, and Japan. It prefers cooler conditions and can have poor performance during hot, humid summers. In addition, it prefers moist, acidic, well-drained soils in full sun. It is resistant to borers that commonly affect other mountain ash species, making it one of the best choices for pest resistance and form. It is not tolerant of air pollution nor street-side conditions or high salt, but can withstand strong winds and is easy to transplant. Sorbus alnifolia drops small fruits and a moderate number of leaves, with the heaviest shedding in the fall.

Sorbus americana, or American mountain ash is native to Ontario with a natural range for eastern North America from Quebec and Ontario to Georgia. American mountain ash is not a 'true' ash, and as such is not susceptible to the emerald ash borer. It is best grown in moist, acidic, humusy, well drained soils in full sun. It is not resilient to urban stresses and may be best suited for park and restoration plantings. Young stems and thin bark require protection from winter browsing. The seeds are reported to be poisonous, but the fruits are enjoyed by many birds and mammals. Sorbus americana drops small fruits and a moderate number of leaves, with the heaviest shedding in the fall.

Sorbus aria, or whitebeam mountain ash, is a non-native to Ontario originating in parts of Europe, North Africa, and temperate Asia. It prefers moist soils and is sensitive to hot, humid summers and urban pollution. This short-lived small tree is mostly found on acidic soil. It produces fruits that are attractive to birds and mammals and provides essential winter food for wildlife.

CAUTION: INVASIVE TENDENCIES. Sorbus aucuparia, or European mountain ash, is non-native to Ontario, originating in Europe and Western Asia and is considered to have invasive tendencies as it is known to naturalize and outcompete native trees and shrubs in North America. It prefers a moist, well-drained soil that is rich in organic matter, and does not do well in waterlogged or overly dry soil. This species is often short-lived and does not tolerate compacted soil. Its fruits provide a valuable food source for birds, but it is known for having poor branch connections. It is considered moderately messy due to the fruit drop and leaf litter that require regular cleanup. A good alternative is Sorbus americana.

Sorbus decora, or showy mountain ash, is native to eastern North America with a range extending from Labrador to scattered populations in North Carolina. It prefers moist soils and is sensitive to hot, humid summers and urban pollution. This short-lived small tree is mostly found on acidic soil. It produces fruits that are attractive to birds and mammals and provides essential winter food for wildlife. Sorbus decora drops small fruits and a moderate number of leaves, with the heaviest shedding in the fall.

Sorbus intermedia, or Swedish whitebeam, is a non-native to Ontario originating in northwestern Europe. Swedish whitebeam prefers moist, acidic and well-drained soil, in full sun. This species is well adapted to cool mountain climates, and may struggle in hot, humid conditions. This tree species has been planted across North America as a beautiful ornamental tree.

Sorbus x thuringiaca, or oakleaf mountain ash, is a hybrid tree resulting from the cross between Sorbus aucuparia and Sorbus aria, both of which are native to Europe. Oakleaf mountain ash are adaptable to a wide range of soil pH levels, from acidic to alkaline, and thrive in full sun. It is relatively disease-resistant, with no major insect or disease issues reported, making it an easy choice for planting. This tree can also be successfully transplanted as a bare root. A notable cultivar, Fastigiata, has a fastigiate form and grows to twice the height of the standard species. The oakleaf mountain ash is valued for its aesthetic appeal, environmental tolerance, and ease of care, making it a versatile addition to both residential and commercial landscapes. Sorbus x thuringiaca drops small fruits and a moderate number of leaves, with the heaviest shedding in the fall.

Styphnolobium japonicum, or Japanese pagoda tree, is native to China and Korea. It features fragrant summer flowers but may take up to 10 years to bloom. It prefers moist, well-drained soils but can tolerate a range of soil types including loam, clay, and sandy soils, as well as alkaline, dry soils and road salt. Its seeds are reportedly toxic and should not be ingested. When grown in open areas, it tends to branch low to the ground. The tree has weak wood, making it prone to breaking under strong winds, severe weather, or heavy snow. Styphnolobium japonicum drops small, papery seed pods and a moderate number of leaves, with the heaviest shedding in the fall. This tree has emerged as an invasive threat in the mid-Atlantic region of the US and should be monitored closely for spread.

CAUTION: INVASIVE TENDENCIES. Syringa reticulata, or Japanese lilac tree, is non-native to Ontario originating in Eastern Asia. It prefers well-drained, fertile soil, with a slightly acidic to neutral pH, with full sun to partial shade. The common cultivar ivory silk is now overplanted in Ontario, and planting is recommended only for particular sites requiring a low-profile salt/compaction tolerant tree. It should be pruned after flowering and benefits from good air circulation. Full sun is necessary for prolific flower production, and the tree attracts hummingbirds, insect pollinators, and butterflies, providing shelter and habitat for wildlife. It is considered one of the most trouble-free lilacs but should not be planted near natural areas and is currently closely monitored for emerging invasiveness. Syringa reticulata drops small seed pods and a moderate number of leaves, with the heaviest shedding in the fall. Some suitable alternatives are the Amelanchier and the Halesia carolina.

CAUTION: INVASIVE TENDENCIES. Syringa vulgaris, or common lilac, has invasive tendencies due to prolific suckering and are not recommended to plant. The native range includes rocky hills and open woodlands in southeastern Europe. It prefers rich, moist, neutral to calcareous soil with good drainage. It is known for its sweet fragrance, and is found commonly in hedges in urban areas. For better airflow to prevent mildew, it's recommended to prune the center of the plant and to prune immediately after flowering. Some suitable alternatives are the Amelanchier and the Halesia carolina.

Taxodium distichum, or bald cypress, is a deciduous conifer non-native to Ontario, originating in the southeastern United States, with a range extending from Maryland to Texas and up the Mississippi River. This species is well adapted to a variety of soil types, from wet flood prone areas to drier, upland locations. With a pyramidal shape, it can reach 50 to 70 feet in height, making it an excellent choice for large parks, streetscapes, and rain gardens, but not ideal for areas with limited soil volume. It is highly tolerant of salt, clay, and air pollution, making it suitable for urban landscapes. There are several cultivars, such as 'Cascade Falls,' a weeping variety, and 'Green Whisper,' a tall pyramidal form, which offer a range of growth habits and aesthetic options. Although it generally faces few insect or disease issues, it can suffer from chlorosis in alkaline soils.

Taxus baccata, or English yew is non-native to Ontario, originating in Europe with a range that extends down to Northern Africa. It prefers a well-draining loam soil, with a slightly acidic to neutral pH. It tolerates pruning well and responds positively to it, and can be grown as a hedge. However, all parts of the plant are toxic and can be fatal if ingested by humans, domestic animals, or livestock. The English yew is intolerant of temperature extremes and is not reliably winter hardy, making it susceptible to winter burn in exposed sites. It should be planted in a sheltered area to minimize exposure to cold winter winds. Insect pests such as mealybugs, scale, and vine weevils can also affect this plant. Deer also browse the foliage heavily in winter.

Thuja occidentalis, or white cedar, is a versatile evergreen tree native to eastern and central North America. Typically reaching heights of 20 to 40 feet in cultivation, mature trees in the wild can grow up to 60 feet tall. This species thrives in well-drained, medium moisture soils and prefers full sun to partial shade. It is tolerant of a variety of soil conditions, including clay and wet soils for short periods of time, but struggles in dry conditions and is not tolerant of prolonged flooding. It can also experience winter burn in exposed locations and may suffer from damage due to ice and snow accumulation and it is not highly tolerant of salt. Numerous cultivars have been developed, offering different growth habits and tolerances, such as 'Smaragd' and 'Nigra,' which are noted for maintaining their green colour in winter. The species has a broad ecological range and is well-suited for use in residential and park settings, adding both aesthetic and functional value to gardens and landscapes.

Thuja plicata, or western red cedar, is non-native to Ontario originating in the Pacific Northwest, extending from southern Alaska along the Pacific coast to northern California, and eastward into the northern Rockies of British Columbia and Montana. It grows best in humus-rich, well-drained soils, and is adaptable to different pH levels but does not tolerate drought or dry winds. Due to its shallow rooting and intolerance of high/dry head, it is not recommended for planting in urban areas.