The latest info on plant pests, pathogens, and weeds.

Tree Identification Tips

Damage from invasive insects like the Asian Longhorned Beetle (ALB) and Emerald Ash Borer (EAB) is easiest to spot in winter and early spring, without leaves blocking our view into the upper canopy. But in winter, there are no leaves on the trees, so how do we identify host species? Check out our winter tree id tips:

1) Determine whether the branches opposite or alternate.

No matter what the season, this should always be your first step in tree id. Only four types of native trees in New England have opposite branching. The easiest way to remember them is with the pneumonic device “MAD Horse”: M=maple, A=ash, D=dogwood, and Horse= horse chestnut. Maple is the key host tree for ALB, while ash is the host for EAB.

2) ID ALB and EAB host trees using these key winter characteristics.

Knowing several key characters for each species is important for identifying trees throughout all seasons. Things like tree silhouette, buds, flowers, fruits, bark, leaf shape, and habitat can all help determine genus and species. In winter, check for these characters to id ALB and EAB host trees:

    Red maple flower buds (photo by J. Forman Orth)

  • Red Maple has red buds and flowers.
  • Silver Maple looks similar to Red Maple but does everything “more”—the buds are bigger and the flowers are showier.
  • Sugar Maple has sharp, pointy buds and bark that peels in vertical lines. Remember “sugar = sharp.”
  • Birches can often be easily recognized by their peeling bark. Also, look for birch flower buds, knows as catkins, at the tips of the branches.
  • Horse chestnut is most easily distinguished by its thick, dark colored branches and sticky buds. Horse chestnuts have large, compound leaves so you’ll notice there is a lot of spacing between the twigs on the branches.
  • Willow (photo by Matt Lavin)

  • Elm has terminal buds that point at a 45 degree angle. The ends of elm branches also tend to be reddish in color.
  • Willows often have distinctly yellowish twig bark. Also, look for the graceful, drooping branches of weeping willows, a common ornamental tree.
  • Ash buds are dark and bulbous. Leaf scars on ash resemble smiley faces. Ash trees have compound leaves, so you’ll notice there is a lot of spacing between the twigs on the branches. (Ash is a host for EAB and ALB)

Comments are closed.