Hues of green with splashes of white and red. Early summer provides its own color extravaganza. Each tree species has a unique nature niche adaptation timing for leafing out that expresses a shade of green color.
Many trees flower before their leaves emerge. This aids trees that are wind pollinated. Early flowering helps maples that are both insect and wind pollinated. Flowering prior to leaf out makes it easier for insects to find flowers for the nectar reward. Insects carry pollen to flowers of the same tree species for cross fertilization.
Insects seek a nectar reward and are unaware they are enlisted as a third party to a sexual transaction for delivering pollen to an egg. Insects see plant colors differently. Their eyes capture ultraviolet color our eyes do not. Our eyes see reds insects do not. Birds, humans with other mammals, and insects see the world differently.
Scientists use ultraviolet photography to discover how insects perceive flowers. What looks like a white flower to us might have vivid color for an insect. Splashes of white tree flowers in the spring woods like serviceberry and cherry might look different to a bee, butterfly, or fly.
As brown branches suddenly transform with flowers followed by leaves, we experience shades of green that rival fall colors. It is joy when driving the highway to witness the multitude of greens. Each species contributes its own hue to the mosaic of forest color. Leaves released from buds usually have red anthocyanin sun block in expanding embryonic leaves that protects new delicate leaves from being sunburned.
Green chloroplasts absorb most sunlight colors in the leaves but reflect green. The concentration of chloroplasts varies to create varying light to dark shades of green in trees. Notice of the subtle color pageant that could easily be missed. Though it is not as obvious as the fall color spectacular, it is remarkable.
When leaves emerge from buds, they expand faster than they can grow. Leaf cells formed last summer and their growth waited in buds all winter. The cold spring delayed leaf emergence this year. When conditions allow, embryonic leaves fill like water balloons and leaves take weeks growing additional cellular substance. Feel the delicate nature of a newly expanded leaf and then the sturdy strength of an older leaf a few weeks later.
We experienced what I call a Minnesota spring. When we lived in northern Minnesota, winter hung on until late April. Then suddenly, conditions changed and spring transitioned to summer in a few short weeks. In “normal” years, spring last about twice as long here. We get to enjoy ephemeral flowers like hepatica, trout lilies, and trilliums longer. Tree flowering sequence is also expanded over a longer period.
This year plants had a narrower flowering time span. It was necessary to look quickly or miss the beauty. We can still witness the varied hues of green that will disappear among trees by the official beginning of summer on the 21 June solstice when the sun appears to make an about-face and begin its journey southward.
Though summer officially begins when the sun reaches its northmost point, I consider that too nebulous and difficult to observe. For me, summer begins at a different time with phenological progression. Phenology is the sequence of plant flowering, bird migration or other biological occurrences associated with climate.
Most bird migration waves have come and gone and spring flowers wane by the time the last tree species leaves emerge. Summer resident birds are on nests. Spring beauty, hepatics, and trout lilies give way to summer flowering plants. I consider that to be the beginning of summer.
Leaves appear latest on oaks trees marking an easily observed beginning to summer. Depending on the year, summer begins on slightly different dates when tree phenology settles to a common hue of green for the coming months.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at firstname.lastname@example.org – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.