Ash color is often used to help identify different tree species. Two of the most common ash tree species found across North America are black ash (Fraxinus nigra) and brown ash (Fraxinus profunda). Although their names imply differently colored wood, is brown ash really different from black ash? Let’s take a closer look.
Quick Answer
Brown ash and black ash are two distinct tree species – they are not the same. While both have similar growth habits and uses, brown ash tends to have a lighter heartwood color that is more brownish, while black ash heartwood is darker and more grayish-brown. However, there can be some overlap in color.
Growth Habits
Black ash and brown ash have very similar growth habits and ranges. Here are some details:
- Both species are medium to large deciduous trees, reaching 60-80 ft in height.
- They have an upright oval crown shape when grown in the open.
- The bark is tight with narrow fissures forming scaly ridges.
- Male and female flowers bloom in separate clusters in spring before leaf emergence.
- They are found across much of eastern North America, with black ash more northern and brown ash more southern in range.
- Both prefer moist soil conditions and are commonly found in wetlands.
Given their similar growth characteristics, black ash and brown ash can be very difficult to tell apart by visual examination alone. Diagnosing small saplings or trees without heartwood exposed generally requires analysis of the leaf characteristics or growing range.
Leaf Differences
One way to distinguish black ash from brown ash is by differences in their leaf shape and color:
- Black ash – Leaves are 8-12 inches long, with 7-11 leaflets per leaf. Leaflets are stalkless, oval or lance shaped, with tiny rounded teeth along the edges. Leaf color is a lustrous dark green above and glaucous (blue-green) below.
- Brown ash – Leaves are 5-9 inches long, with 7-9 leaflets per leaf. Leaflets are short-stalked, lanceolate shaped, with very fine sharp teeth along the edges. Leaf color is dull dark green above and glabrous (no coating) below.
So in summary, black ash leaves tend to be larger, stalkless, and bluish-green on the underside compared to brown ash. However, leaf characteristics can vary quite a bit depending on light exposure, age, and other factors. DNA analysis provides the most certain identification.
Heartwood Differences
The most obvious difference between these two ash species lies in the color of their heartwood – the inner wood of older trees. Here are some details on the heartwood colors:
- Black ash – Heartwood is a grayish brown, sometimes with a faint olive tone. The wood is not as dramatically dark as the name implies.
- Brown ash – Heartwood light brown to medium brown. Color is more uniform and lacks olive tones.
There is some overlap in colors, but black ash tends to be darker, while brown ash is lighter brown. However, considerable variation exists and colors can blend together. Using range maps and leaf characteristics provide the best identification.
Wood Properties
Despite color differences, black ash and brown ash wood share many similar properties. The wood of both species is characterized by:
- Straight grain
- Medium to coarse texture
- Good strength properties relative to weight
- Good shock resistance
- Good machining qualities
- Moderate durability
The wood is used interchangeably for applications like baseball bats, tool handles, furniture, flooring, millwork, and crates. Brown ash tends to be slightly heavier while black ash has a bit more shock resistance. But for most uses, the species are functionally the same.
Wood Anatomy
Under a microscope, the wood anatomy of black ash and brown ash is virtually identical. Both exhibit:
- Ring porous structure
- Solitary pores in earlywood, grouped pores in latewood
- Mean pore diameter of 0.1-0.2 mm
- Tyloses occasionally present in pores
- Rays not visible without lens
- Parenchyma paratracheal, diffuse-in-aggregates
There are no consistent anatomical differences between these species significant enough to allow certain identification without DNA testing. The main diagnostic feature is simply the color of the finished heartwood.
Range Maps
The natural growing range is one clue to help identify black ash vs. brown ash:
| Species | Native Range |
|---|---|
| Black Ash | Newfoundland to Manitoba, south to Iowa and Pennsylvania |
| Brown Ash | Nova Scotia to Minnesota, south to Oklahoma and Georgia |
As shown, black ash has a more northerly distribution in Canada, while brown ash extends farther south into the central United States. So if an unknown sample originates from the southern part of the range, it is more likely to be brown ash.
Ecological Differences
There are some subtle ecological preferences that can help differentiate black and brown ash:
- Black ash – Occurs in mixed hardwood swamps, forested wetlands, along streams and lake edges. Prefers more acidic bog-like sites.
- Brown ash – Occurs in bottomland hardwood forests, slopes, bluffs. Tolerates occasional flooding but prefers better drained soils.
So while both occur in wet areas, black ash is more strongly linked to boggy, peaty soils. Brown ash has a slightly wider habitat range extending into uplands. If the exact wetland conditions are known, it can aid identification.
Susceptibility to Emerald Ash Borer
Unfortunately, both black ash and brown ash are highly susceptible to attack from emerald ash borer – an invasive insect pest. Some key threats include:
- Nearly 100% mortality observed in natural stands infected with emerald ash borer.
- The species lack effective resistance mechanisms and EAB larvae readily survive in their wood.
- Widespread decline and death of black ash and brown ash is occurring in infected regions.
- Mortality typically occurs within 2-4 years after infestation.
Efforts are underway to try and breed resistance into these species. But for now, most existing black and brown ash trees are at grave risk as emerald ash borer continues to spread through North America.
Cultivation
In cultivation, black ash and brown ash share similar requirements:
- They perform best in moist, well-drained loam soils.
- Acidic soil pH between 5.5-7.0 is ideal.
- Partially sun to full sun exposure.
- Moderate growth rate when young, slowing with age.
- Tolerant of wet soil but not permanently flooded.
- Withstands light shade when young.
- Resprouts readily when young if pruned or damaged.
- Few serious pest problems aside from emerald ash borer.
The main cultivation difference is that brown ash will better tolerate drier conditions than black ash. But both require abundant moisture for best growth and performance.
Availability
Black ash and brown ash have limited availability in the nursery trade. Some key notes:
- Uncommon to find either species sold as landscape specimens.
- Most material is harvested directly from natural stands.
- Declining supply due to emerald ash borer mortality.
- Brown ash has slightly better availability than black ash.
- Planting stock is often not distinguished between the two species.
- Origin should be checked as range maps don’t overlap completely.
It can be difficult finding specifically identified material. Both species may become even more scarce as emerald ash borer spreads through their native ranges in the coming years.
Pricing
Price data for specifically identified black or brown ash trees is limited. But in general:
- 1-2″ caliper trees may range from $100-$300 each wholesale.
- Larger specimens 6-8″ caliper likely range $500-$1,000.
- Black ash and brown ash prices are similar.
- Significant volume discounts for orders of multiple trees.
- Price will depend on tree grade, scarcity, and supplier location.
Quantities are becoming more restricted, which has driven up wholesale prices in recent years. Large logs and lumber are priced per board foot and determined by wood quality.
Substitutes
Given their declining availability, some potential substitutes for black ash and brown ash include:
- White ash (Fraxinus americana) – Near identical properties with better resistance to emerald ash borer.
- Green ash (Fraxinus pennsylvanica) – Also similar with some EAB resistance.
- Red maple (Acer rubrum) – Fast growth and wide moisture tolerance.
- Silver maple (Acer saccharinum) – Tolerates wetness, frequently grown.
- Yellow birch (Betula alleghaniensis) – Has good wet site tolerance.
For wood use, oak, maple, and hickory species also substitute well. Ultimately the best choice depends on factors like intended use, site conditions, and availability.
Conclusion
In summary, while black ash and brown ash share many similarities, they represent two distinct species:
- Brown ash has lighter brown heartwood, while black ash is darker gray-brown.
- Leaf shapes differ, with brown ash having shorter stalked leaflets.
- The range maps do not completely overlap.
- Black ash prefers wetter bog-like habitats.
- Wood characteristics and properties are nearly identical.
- Both are highly vulnerable to emerald ash borer as native trees.
- Stock availability is declining but brown ash is slightly more available.
So while closely related, experienced observers can distinguish these two common ash species based on several visual cues and habitat preferences. But side-by-side, their similarities are far more prominent than their differences.
