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Looking Up: Tree Flowers

March 27, 2020 12:00 AM
By: DCNR

Looking Up: Tree Flowers

Downy serviceberry

We all have our favorite signs of spring -- returning of migratory birds, spring peepers, warmer weather, gentle rains, and wildflowers.

Some of our favorites are searching out the first wildflowers of the season, specifically skunk cabbage, followed by spring ephemerals and tree flowers.

Looking up into the trees can provide you a different perspective and new spring wildflowers to add to your list.

Many native tree flowers like flowering dogwood, redbud, and shadbush (serviceberry) are large, fragrant, and showy -- easily catching attention whether planted or naturally occurring in woodlands.

But there are many other colors and shapes of tree flowers to discover before the leaves emerge.

Red Maples

Red Female Maple.jpg
Red maple, female flowers 

Red Male Maple.jpg  
Red maple, male flowers

Look up to see red maple flowers (some of the earliest blooms), appearing before leaves and rather tiny (1/4 inch); but when they bloom in unison, the trees glow red.

Up close, you will see male and female flowers appearing either on separate branches of the same tree or on separate trees.

The flowers have five petals and five sepals, but males will have five to 10 long stamens and females will have two bright red pistils.

Ash Trees

Ash Male.jpg
Ash, male flowers

Ash Female Cropped.jpg
Ash, female flowers

Another example of tree flowers that are either male or female are the ash species in the genus Fraxinus. In Pennsylvania, this includes white, green, and black ash.

Individual trees have all female or all male flowers. Flowers of both sexes are small, do not have petals, and grow in clusters.

The most obvious structure you will see are the numerous stamens on males and single pistils on female flowers.

If you miss these flowers in the spring, check for the “canoe paddle-like” fruits or samaras in the summer -- these are the female trees.

Tree Flowers Without Petals

Bigtooth Aspen Catkins.jpg
Bigtooth aspen catkins

Red Oak Over Mature Catkins.jpg
Red oak over-mature catkins

In many tree species, flowers are also arranged in catkins or aments, which are drooping clusters of tiny flowers without petals.

These worm-like structures contain all male or all female flowers.

The structures of catkin flowers differ by tree species; however, numerous stamens give male catkins a showier appearance.

Common native tree species in Pennsylvania that produce catkins include:

  • Willows
  • Poplars
  • Birches
  • Oaks
  • Alders
  • Walnuts
  • Hickories

In the spring, before we see them, we may feel the effect of wind-borne pollen from male catkins, in the form of allergies. Look up -- you may just see catkins dangling in the wind.

Look Up Next Time You Are Outdoors

Getting outside this time of year is important and whether you are hiking, walking, or gardening; don’t forget to look up!

There is a whole new level of spring wildflowers waiting to be discovered.


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