| General Description | Fraxinus nigra is a medium-sized deciduous tree native to eastern North America. The black ash tree is often compared to its close relatives- the green or white ash, due to its closely shared characteristics. It has also been classified as critically endangered following the invasion of the emerald ash borer. |
| ID Characteristic | The main differential between the black ash and its relatives, is the climate it prefers to grow in, they thrive in wet, humid soils while the other ashes favour dry ones. Key features for proper identification also include the opposite branching structure and compound pinnate leaves that have no stalks, one smooth surface and one hairy surface. Another notable distinction includes their susceptibility to ash borer disease. |
| Shape | The straight, upright branches form an open or rounded crown depending on age, time of year and overall health of the tree. The trunk will most likely not exceed 65 cm at its peak age of maturity. It has been reported that some black ash crowns begin at heights of up to 15 m. |
| Landscape | The black ash tree does not have many uses in the landscape scene for a few reasons; the migration of the emerald ash borer from north-eastern Asia nearly wiped out the entire population and it is reported that woodworking with ash trees causes skin irritation and even decreased lung function, not to mention the brutal odour that emits from the wood. One known use for the black ash tree was harvesting the wood to turn into baskets in early Canada by indigenous tribes, earning it the common name ‘Basket ash’. They also frequently made canoes and snowshoes because of the woods elasticity and ability to stay bent. |
| Propagation | The black ash is capable of both sexual and asexual reproduction through wind pollination or manual cuttings. Black ashes can be germinated from seed after a vigorous process that usually takes 2-3 years in natural conditions, the seeds are not fertile from shed but require a period of warmth and high humidity to ripen then the seed is treated in a moist, cold environment to break dormancy. The seeds have been studied to have a higher germination rate when collected every 8 years from a tree at least 40 years old. They can also be cultivated through cuttings or vegetative reproduction as the black ash is described as a “vigorous sprouter.” Seedlings have approximately a 50% survival rate in full sun and can grow up 15cm in the first year. |
| Cultivation | Seeds generally germinate best in peat or mineral soils with a high concentration of organic matter. They can germinate in litter or under 1-2 cm of soil. Can be planted in full sunlight or shade but will die eventually in shade as it matures. They are very pH tolerant, can grow in moist aerated clay or peat soils in pH of 4.4-8.2. |
| Pests | The biggest threat to black ash trees is the emerald ash borer that immigrated to North America in the early 2000s, it is a green Asian beetle that lays eggs in ash crevices. Their larvae hatch and feed underneath the bark for up to 2 years, usually killing the tree within a few years. They are extremely invasive and are responsible for the black ash becoming a critically endangered species. |
| Notable Specimens | The highest concentration of ash trees lies in eastern Canada; Ontario, Quebec, Newfoundland. |
| Habitat | Fraxinus nigra prefer poorly drained swamps, bogs, woodlands, gullies, lowlands, foothills, valley flats, and stream and lake shores throughout its north-eastern range. They thrive in both clay and shallow peat soils where weather is cool. |
| Bark/Stem Description | The bark and branches are grey and cork-like when young, the tree matures into a scaly bark over time. The branches have very distinct black/dark green bud scars. |
| Flower/Leaf Bud Description | In May, you can expect flowers of green and white, forming lateral panicles that sprout just before the leaves. Male and female flowers appear on separate trees that lack both a calyx and petals, although uncommon hermaphrodites have been found. |
| Leaf Description | 5-9 single green leaves up to 20 cm long and pinnately compound, they have serrated margins and are arranged in an alternate position. They green leaves turn into a rich yellow in autumn. Will turn black when frost burned by conditions. |
| Fruit Description | The paired samaras are approximately 3-5 cm long. They are a pale green and transition into a brown when old. |
| Colour Description | A calm lush green throughout the summer months, a rich gold foliage in autumn. The flowers are both green and white in early spring. The bark is a dull grey that remains unchanged. The leaves will change to the colour of black when the tree has been frost burned. |
| Texture Description | The bark of a young tree is somewhat smooth, as it grows laterally with age it begins thickening the crown and cork cambium resulting in a more coarse feel on the external side with visible ridges running vertically. |