Black ash

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More names for this tree

Anishinaabemowin: Baapaagimaak

The Dakota and Anishinaabe were among the earliest people to name Minnesota’s plants and animals, as well as to understand them in relation to Minnesota’s climate and seasons. Those original names are still in use, and several are included on the Season Watch website. However, complete translations were not available.

Latin (or scientific name): Fraxinus nigra

The scientific community has a convention of assigning agreed-upon Latin names to every kind of organism. Using scientific names helps people communicate confidently about the same organism and organize lifeforms based on how closely related they are.

Page contents

About

Visual guide to phenology

Graphs and historical data

More resources

Image of black ash tree with green leaves at the edge of a wooded area
August 26, 2018, St. Louis County, Minnesota
Photo © Norma Malinowski, some rights reserved (CC-BY-NC)
iNaturalist observation

About the black ash

  • Black ashes have compound leaves, meaning a single leaf is composed of multiple leaflets. The leaflets are oval-shaped with fine serrations around the edge. Each compound leaf is made up of seven to eleven leaflets.
  • Growing throughout Minnesota, black ash can be found in low-lying, moist areas such as bogs and river beds.
  • Black ashes have both male and female flowers growing on the same tree. The purplish flowers emerge before the leaves in early spring.
  • The fruit of the black ash is called a samara. The samara is composed of a single seed and a paddle-shaped wing, allowing the seed to be dispersed by the wind.
  • A deciduous tree, black ash leaves change color and drop to the ground in the fall.
  • Unfortunately, black ash trees are highly susceptible to the invasive emerald ash borer beetle.

Visual guide to phenology

Watch for the appearance of leaves, flowers, and fruits. Take notice of when flowers open and fruits ripen.

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Note to observers

This page explains general clues to watch for when observing black ash phenology. However, this page does not instruct observers on how to identify this plant or collect data in a standardized way.

Photo looks up at a leafless black ash canopy against a brilliant blue sky
Ripe dried ash fruit are tan and dry. The flat seed is within the oblong-shaped samara.
Looking up at leafless black ash brances against brilliant blue sky. Dark ragged clusters are the structures left over from last year's male flowers.
Close-up photo showing the tip of a black ash branch. A hoof-like shape at the tip is where this year's leaves will form. Below that, bud scars are where last year's leaves dropped.
The deerhoof-shaped buds are slightly expanded with a subtle ridged texture at their tips.
Terminal leaf buds have expanded and started to draw apart at their tips. Snowy winter scene in the background.
Green is now visible, new leaves emerging from terminal leaf buds.
Yellow-green leaves are unfolding at the twig's tip. The unfolding leaves have a ridged texture because ash leaves are compound.
Fresh and bright green leaves are slightly glossy. Dappled sunlight in a forest.
Unripe fruits are bright yellow-green, flat, and oblong.
Looking up at compound leaves that form the canopy of a black ash tree.
Brilliant yellow leaves of black ash in autumn.
Tip of black ash twig showing terminal buds where next year's leaves will grow and yellow petioles of this year's leaves, which will fall off the twig.
Tip of black ash twig with scars where this year's leaves have fallen off.
Leafless black ash tree against a gray sky. The black ragged clusters are what remains where last year's male flowers were.

Graphs and historical data

Note: The Orientation Center provides a map, as well as information on reading graphs; interpreting summary statistics, who collected the data and how; and how to download datasets for independent exploration.


Itasca County

Leaf budbreak

  • Earliest: May 19 (occurred in 2012)
  • Average: May 27
  • Latest: June 6 (occurred in 1993)
Scatterplot showing black ash phenology in Itasca County, Minnesota

Download this dataset (.csv file)

All leaves colored

  • Earliest: August 19 (occurred in 1986)
  • Average: September 6
  • Latest: September 17 (occurred in 2008)
Scatterplot showing black ash phenology in Itasca County, Minnesota

Download this dataset (.csv file)

More resources

Black ash (Fraxinus nigra) in the Minnesota Biodiversity Atlas

Black ash (Fraxinus nigra) in Nature's Notebook

 

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Times of year

Co-author: Audrey Negro, Minnesota Master Naturalist