10/13/2026
Fernwoodâs trees are definitely putting on a show right now - come see!
Every year, a variety of trees change their leaves to gold, crimson, amber, and even jewel-toned purple. For those who live in places without a major color shift, or on treeless plains, deserts, or deserted islands, feel free to scroll on.
Just kidding. Come back!
Well, fine then.
Today, we tackle an age-old question: Why are you wearing that sweater?
Apologies. Thatâs apparently next week.
Todayâs question is: Why do some leaves fall off?
Because theyâve had enough of the treeâs drama. We said it. Months of photosynthesis. Chlorophyll everywhere. Constant demands for sunlight. Not one person asking how the leaf is doing. Eventually, every leaf reaches its limit.
Sorry. The supervisor is requesting a sidebar.
And weâre back.
Deciduous trees are responsible for much of the colorful annual display we associate with autumn. For most of the year, a green pigment called chlorophyll helps leaves capture sunlight for photosynthesis. But as days get shorter and temperatures change, trees begin to stop producing chlorophyll. The green fades, revealing other pigments that were there all along, producing those spectacular yellows, oranges, reds, and purples.
So, technically, the leaves werenât suddenly becoming colorful. They were just green until further notice. At the same time, the tree begins forming a special layer of cells where the leafâs stem connects to the branch. This eventually weakens the connection between the leaf and the tree. Then gravity, wind, rain, or someone taking a very enthusiastic photograph nearby, finishes the job.
Down goes the leaf.
Why do some leaves stick around?
Conifers are like that coworker who never takes a sick day.
While broadleaf trees are dropping leaves left and right, evergreens continue showing up year after year, looking suspiciously productive. They donât complain.
Outwardly.
Their needles are built differently from broadleaf leaves and generally lose less water to the air. Thatâs particularly useful during winter, when much of the precipitation may be locked up as snow and unavailable to the tree until it melts.
So, while some conifers can photosynthesize on warmer winter days, keeping their needles is mostly an energy-saving strategy. Rather than growing an entirely new set of leaves every year, they keep their needles for several years and replace them gradually. Basically, conifers reuse their leaves. Like reusable water bottles, but considerably more efficient and much less likely to be left in the back of your car until March. This is why an evergreen can remain, well, ever-green, while the trees around it dramatically disrobe every autumn.
Which brings us back to the leaves.
Theyâre colorful.
Theyâre complicated.
Theyâre falling.
And apparently, theyâve been doing this for millions of years without requiring a single committee meeting.
We hope this has been helpful.
Enlightening.
Educational, perhaps.
Well, itâs been something.
The supervisor says thatâs enough.
Whoa, what a ride this has been. If you're still reading this, why?
P.S. Nice sweater.
NPS Photo
