Carya laciniosa, or shellbark hickory, is native to Ontario and ranges throughout North America, specifically from New York and southern Ontario south to Tennessee and Oklahoma. This species is a slow-growing, long-lived tree valued for its sweet, edible nuts. It prefers well-drained, moist conditions, and partial to full sun. Since it requires ample space to thrive, it's a great choice for larger landscapes. Known for its deep taproot, transplanting can be challenging. Tolerant of occasional flooding and wet sites, it attracts wildlife like birds, small animals, and browsers. Although it faces few serious pest or disease issues, it can occasionally be affected by the hickory bark beetle, pecan weevil, twig girdler, and hickory shuck worm, which may reduce seed production. With its large nuts (largest amongst hickory trees), thick husks, and exfoliating bark, the shellbark hickory can be messy, but its beauty and wildlife benefits make it a valuable addition to plantings. Currently limited availability in the landscape, but with proper seed collection can become more available.

Carya ovata, or shagbark hickory, is a large tree, native to Ontario and ranges throughout eastern US and Canada that provides excellent shade, and reaches heights of 70 to 90 feet. It thrives in moist, well-drained soils and full sun to part shade, making it perfect for larger landscapes and parks. While it adapts to various soil types, including alkaline and occasionally flooded sites, it grows best in rich, loamy soils. Shagbark hickory has a deep taproot, making transplanting tricky, but it's easier if done in spring. It is considered messy due to its fallen nuts, leaves, and shedding bark. It's a resilient tree with minimal pest or disease issues but common ones include hickory bark beetles, pecan weevils, twig girdlers, white heart rot. Despite its slow growth, its shade and natural beauty make it a valuable addition to any landscape. Currently limited availability in the landscape, but with proper seed collection can become more available.

Carya tomentosa, or mockernut hickory, is native to Ontario and ranges throughout eastern North America. This species is a slow-growing, long-lived tree that provides valuable wildlife support, serving as a food source for the larvae of the Banded Hairstreak butterfly and Hickory Horned Devil moth, as well as birds and small mammals. It prefers full to partial sun, and grows best in dry-mesic conditions, and deep fertile loam. Although considered messy, particularly in autumn due to fallen nuts (edible), husks, and leaf drop, it offers significant ecological benefits. With regular maintenance, this tree makes a fantastic addition to landscapes, providing both beauty and habitat for local wildlife. Currently limited availability in the landscape, but with proper seed collection can become more available.

Castanea dentata, or American chestnut, native to Ontario and ranges throughout eastern North America, from southern Maine and southern Ontario to Georgia and Mississippi, is a towering tree that can reach heights of 50-75 feet with a similar spread. It prefers full or partial sun, mesic to dry conditions, and slightly acidic soil that contains loam, clay or rocky material. Due to chestnut blight, it is critically endangered, and planting non-resistant trees is not recommended except for restoration purposes and to maintain the population. It is messy with its edible nuts enclosed in spiny burrs, large leaf drops in the fall, and occasional twigs or branches while also posing challenges transplanting with its deep taproot. Ongoing breeding programs aim to develop blight-resistant varieties, but for now this tree is planted for conservation efforts. Chinese chestnut (C. mollissima) hybridizes with this species, which makes conservation programs a challenge to protect this species genetic diversity.

Catalpa speciosa or Northern catalpa is native to the Midwestern United States, ranging from southern Illinois and Indiana to western Tennessee and northern Arkansas. Although non-native to Ontario, it has naturalized here. It is a fast-growing, potentially aggressive ornamental tree that adapts well to diverse soil conditions, from dry, rocky terrain to mildly swampy areas. Reaching up to 50 feet, it provides excellent shade, making it ideal for large landscapes and parks. Its stunning flowers bloom in late spring and summer, and it attracts pollinators like bees, wasps, and flies. Though it has brittle wood and produces significant litter from flowers, leaves, and long seed pods, its beauty and shade make it a great addition to any landscape.

Celtis laevigata or sugar hackberry is a hardy, is a non-native species to Ontario, originating from the southeastern United States west to Texas and south to northeastern Mexico, and it is also found on the island of Bermuda. It can grow in a wide variety of soils, including sandy, loamy, and clay soils, but prefers well-drained acidic soil. This species is well-suited for urban environments due to its strong resistance to pollution, soil compaction, nutrient poor soil and drought tolerance. It produces sweet, edible red/purple fruits that attract birds and mammals and serves as a host for the Hackberry Emperor butterfly and various moth larvae. This species is often confused with the species Celtis iguanaea and Celtis tenuifolia. Although currently limited availability exists in the tree nursery, this tree could become more popular as demand grows.

Celtis occidentalis or Hackberry, is a resilient native to Ontario tree valued for its adaptability. It is found across North America, ranging from southern Ontario and Quebec through parts of New England, south to the Appalachian region of North Carolina, west to northern Oklahoma, and north to North Dakota. Hackberry is well-suited for urban and rural settings, thriving in alkaline, moist, well-drained soils, and tolerating occasional drought and flooding. It can be a prolific seeder, and the aggressive seedlings can out-compete other Ontario natives in forests. Hackberry is known in the US for successfully invading disturbed waste sites in the urban environment. Tolerant of wind, pollution, and various soil conditions, including wet, dry, and poor soils, it thrives in USDA Hardiness Zones 2 to 9, reaching heights of 40 to 60 feet.

Cercidiphyllum japonicum, or katsura tree, a non-native species from China and Japan, is valued for its attractive foliage, which starts red/purple, matures to green with a bluish tint, and turns vibrant shades of red, gold, and orange in the fall. It thrives in larger spaces and requires ample water for establishment, as well as protection from strong winds and afternoon sun. The tree is tolerant of alkaline and clay soils, road salt, and wet sites. While it generally faces few serious pest or disease issues, it can be stressed by drought and wind, leading to leaf scorch. Transplanting can be moderately challenging, and the tree may experience bark splitting. It is somewhat resistant to deer and requires low maintenance, though there may be some mess from small seed pods and leaves.

Cercis canadensis, or Eastern redbud, is a striking deciduous tree native to Ontario, known for its vibrant pink or purple flowers and heart-shaped leaves that turn yellow in autumn. Its range extends across eastern and central North America, from southern Ontario and the Great Lakes region south to western Texas, Florida, and central Mexico. It thrives in full sun to part shade and adapts to various soils, except consistent wet conditions, making it ideal for urban landscapes, woodland edges, or naturalized areas. While it may shed small flowers and seed pods, the tree supports wildlife with its blooms and fruit, and its edible flowers are often used in salads. It seeds aggressively into gardens. To maintain this species health, regular pruning is required to maintain small crotches.

Chamaecyparis nootkatensis, also known as Alaskan cedar, is non-native species to Ontario with a natural range in the coastal mountains of the Pacific Northwest, including the Cascades, ranging from the Kenai Peninsula in Alaska to the Klamath Mountains in northernmost California. This species thrives in moist, loamy soil and sunny, well-drained sites. Known for its durable, fungi-resistant wood and resistance to insect damage, it's a great screen or hedge species for landscapes. The tree tolerates both summer pruning and pollution.

Chamaecyparis thyoides, also known as Atlantic white cedar, is a non-native species to Ontario with a natural range in the Atlantic coast of North America, ranging from southern Maine to Georgia, and along the Gulf of Mexico from Florida to Mississippi. Thriving in wet areas with poor drainage, such as ponds, streams, and bogs, this species is ideal for pollinators, rain gardens, providing winter cover for wildlife, and serving as a larval host plant for butterflies. Pruning is usually unnecessary, but it should be sheltered from strong winds.

Cladrastis kentukea or yellowwood is a resilient, medium to large deciduous tree native to North America. Its range is restricted to the southeastern United States, extending from western North Carolina west to eastern Oklahoma and from southern Missouri and Indiana south to central Alabama. It thrives in well-drained soils and adapts to both alkaline and acidic conditions. Although rare in its native range and slow growing in its early years, once established, it becomes drought and road salt tolerant, making it a perfect choice for parks or open fields, offering excellent shade. While often requiring corrective pruning, pruning in late winter or spring may cause sap leakage, and its weak branches can be vulnerable to snow, ice, or windstorms. The tree produces beautiful clusters of flowers that attract pollinators.

Cornus alternifolia or pagoda dogwood is native to Ontario and is known for its elegant, tiered branching that resembles a pagoda. Its range extends across eastern North America, from Newfoundland west to southern Manitoba and Minnesota, and south to northern Florida and Mississippi. Thriving in partial shade to full sun, it prefers cool, moist, acidic, well-drained soils but adapts well to poorer soils and clay. While generally low-maintenance, pagoda dogwood may be susceptible to certain issues like Cryptodiaporthe canker, leaf spot, and occasional pests. Regular sucker removal helps maintain healthy growth, and the tree benefits from consistent moisture and mulching during its establishment phase. Ideal for shaded or partially shaded landscapes, it's a beautiful specimen tree for woodlands or naturalized areas. While sucker removal is key to maintaining healthy growth, pagoda dogwood is often a short-lived tree and some should be kept around to ensure the tree's survival.

Cornus florida or eastern flowering dogwood is native to Ontario provides multi-season beauty, and serves as a larval host for the Spring Azure butterfly. In Ontario, it is only found naturally in the Carolinian zone and considered a rare species. Its range extends from southeastern Maine to southern Ontario and Michigan, south to Illinois, Oklahoma, northeastern Mexico, and Florida. It prefers well-drained, acidic soil that is high in organic matter, and pH that is slightly acidic or neutral. Ideal for woodlands or forest edges, it thrives in naturalized areas. Transplanting is difficult as it requires bare roots, but is easier with container or balled-and-burlapped trees.

Cornus kousa, or kousa dogwood, a non-native species from Asia, is drought-tolerant, cold-hardy, potentially self-sowing, and disease-resistant. It prefers well-drained soil rich in organic matter with a slightly acidic to neutral pH (5.5-7.0). However, it is still vulnerable to borers and leaf spot, and it doesn't do well in waterlogged soils due to its shallow root system. It prefers acidic soil and may show chlorosis in high pH soils. Mulching helps keep roots cool, and pruning should be done right after flowering as it blooms on old wood.

CAUTION: MAY HAVE INVASIVE TENDENCIES. Cornus mas, or cornelian cherry, is a low-maintenance, non-native dogwood from Asia and Europe, known for its excellent resistance to dogwood anthracnose and the dogwood borer. It prefers well-draining loam soil with a slightly acidic to neutral pH. It generally faces few pest or disease issues, though it can become vulnerable to borers if stressed. Pruning should be done in spring after flowering to maintain its health.

Corylus americana or American hazel is native to Ontario, and ranges from southern Manitoba to southwest Quebec and throughout most of the eastern U.S. It prefers well-drained, moist soils that are high in organic matter, but is tolerant to a wide variety of soil types and pH ranges. It is a versatile plant that can be pruned year-round and tends to sucker from the roots, requiring regular thinning. It produces edible nuts that mature in September to October and attract seed-eating birds. The tree can be moderately messy with fallen nuts, catkins, and leaves, which may require occasional clean-up. Although availability is limited in the tree nursery, this species is becoming more popular and should become more available in the future.

Corylus avellana, or European filbert, is a non-native species from Europe and Asia that produces edible hazelnuts that ripen in late August and September. It prefers moist, well-drained soils, but is fairly tolerant to different conditions. To maintain its appearance and prevent thicket formation, prompt removal of root suckers is necessary. While it's susceptible to eastern filbert blight and occasional issues like black knot, crown gall, and leaf spot, it remains a productive plant when properly cared for. The tree can be moderately messy with fallen nuts, catkins, and leaves, requiring occasional clean-up. Japanese beetles may also target its foliage, and its pollen and nuts could cause allergic reactions in some individuals.

Corlus colurna, or Turkish hazel, a resilient non-native species from Europe and Asia, thrives in various pH levels and tolerates heat, cold, and drought once established. It faces few pests or diseases, though eastern filbert blight can be a concern. This tree may sucker at the base, requiring regular management. It is ideal for challenging sites, including those with alkaline soil and drought conditions, but has a poor transplant survival rate and is best planted using balled and burlapped or container methods. While it can be moderately messy with fallen nuts, leaves, and catkins, it is well-suited for urban and naturalized landscapes.

Cotinus coggygria, or smoketree, is non-native to Ontario, with potentially invasive tendencies. This shrub or small tree originates from Europe and Asia, and is known for its pest and disease resistance. It tolerates a wide range of soil conditions, including a pH between 4-8, and different soil textures for sandy to clay soil. To maintain its shape, regular pruning is required. Caution should be used when pruning as its resinous sap may irritate the skin on contact. An alternative could be Cotinus obovatus.

Cotinus obovatus, or the American smoketree, is a stunning species that thrives in a variety of soil conditions and is ideal for urban landscapes and woodlots as shrubbery. Native to the southern United States, it is drought and heat tolerant, low-maintenance, and resistant to deer. It grows well in high pH, alkaline soils, and should be located in full sun or partial shade. While its resinous sap has a strong odour, it generally faces minimal insect or disease issues. To maintain optimal health, avoid over-watering, over-fertilizing, and planting in wet, low-lying areas. The smoketree's shallow root system makes it easy to transplant. The American smoketree is native to rocky, usually mountain soils from Kentucky, Tennessee, and northern Alabama west to Oklahoma For a native alternative in Ontario, consider the eastern redbud. Currently not available in the tree nursery, due to its aesthetic beauty and adaptable nature, nurseries are trying to cultivate this species.

Crataegus crus-galli var. intermis or Thornless cockspur hawthorn, is a native cultivar to Ontario and ranges from Quebec to North Carolina and Kansas. This thornless, small flowering tree is known for its attractive spring blooms and persistent red fruit. It thrives in well-drained soils with full sun but can tolerate light shade, mild drought, and urban pollution, making it versatile for landscaping. Although its flowers have an unpleasant fragrance, its adaptability and thornless branches make it an excellent choice for parks and open woodlands.

Crataegus laevigata, or the English hawthorn, is a small, low-branching tree known for its profuse spring bloom, and is native to Europe and North Africa. It thrives in full sun, moist, well-drained soils, and requires minimal pruning in late winter or early spring. It is recommended to plant as buffer strips around parking lots, for median strip plantings in the highway, and is a useful reclamation plant, screen, and residential street tree. This species has been successfully grown in urban areas where there is air pollution, poor drainage, compacted soil, and drought are common, making it useful in urban tree plantings.

Crataegus mollis or Downy hawthorn, native to Ontario, is a deer-resistant tree that thrives in dry soils. Its range extends from southern Ontario and Michigan to eastern North Dakota, and south to Denison, Texas, and Arizona. It can grow in a range of soil pH, and prefers moist or wet soil, but can tolerate drought. It features attractive flowers and berries but has large, dangerous thorns, requiring careful placement. The tree tolerates pruning but may suffer from rust, scab, and leaf blight, leading to damaged leaves by summer's end.

NOT RECOMMENDED TO PLANT: INVASIVE TENDENCIES. Crataegus monogyna, or one-seeded hawthorn, is not recommended to plant, due to its invasive tendencies. Native to Europe and Asia, it aggressively spreads by seed, forming dense, thorny thickets in woodlands and fields. It prefers well-drained soils, but is tolerant of a wide variety of soil conditions and nutrition levels, however, it will not tolerate wet or waterlogged soils. While it faces few pests, it is susceptible to fire blight and should be avoided near orchards. Its seeds are dispersed by birds, further contributing to the suppression of native vegetation. This species is expected to continue spreading across North America, and its introduction should be prevented. Additionally, it can be moderately messy with falling fruits, leaves, and spring flowers. Consider planting thornless cockspur hawthorns (Crataegus crus-galli var. inermis) or other Crataegus species as an alternative.