Why don’t evergreens lose their leaves?

Coastal Redwood, El Dorado Hills (9/7/17) John Poimiroo

Actually, they do.  It just doesn’t happen all at once, with few exceptions.

Evergreen trees have both broad leafs and needles. Madrone, magnolia and photinia are examples of broadleaved evergreens, while pine, fir, cedar, spruce, and redwood have needled leaves.

Evergreen needles can last anywhere from a year to 20 years, but eventually they are replaced by new leaves. When that happens, the old needles turn color and drop, but not all together and not as dramatically as deciduous trees (e.g., maple, oak, dogwood, alder, birch).

The reason needles are green is that they are full of chlorophyll which photosynthesizes sunlight into food for the tree. It also reflects green light waves, making the needles look green.

Needles, just like deciduous leaves, contain carotenoid and anthocyanin pigments. You just don’t see them until the green chlorophyll stops being produced. Once that happens, hidden carotenoids (yellow, orange and brown) emerge, as is seen in the above photograph.

Additionally, red, blue and purple Anthocyanins – produced in autumn from the combination of bright light and and excess sugars in the leaf cells – also emerge once the chlorophyll subsides.

Yes, even evergreen leaves change color… eventually.

Evergreens that drop leaves at one time include the: Conifers Larch, Bald Cyprus and Dawn Redwood.

In snowy regions, evergreen trees are able to carry snow because the waxy coating on needles, along with their narrow shape, allows them to retain water better by keeping it from freezing inside (which would otherwise destroy the leaf).

Needles also prevent snow from weighing down and breaking branches. Finally, needles allow an evergreen tree to sustain the production (though slowed) of chlorophyll through winter. Whereas, broadleaved deciduous trees would be damaged if they kept producing chlorophyll and didn’t drop their leaves.

Evergreen trees do lose their leaves and the leaves do change color. It just isn’t as spectacular. 

Why do deciduous trees lose their leaves?

Snowcreek (11/2/15) Alicia Vennos

It’s survival not just of the fittest, but of the wisest.

Deciduous trees drop their leaves in order to survive.  As days grow shorter and colder, deciduous trees shut down veins and capillaries (that carry water and nutrients) with a barrier of cells that form at the leaf’s stem.

Called “abscission” cells, the barrier prevents the leaf from being nourished. Eventually, like scissors, the abscission cells close the connection between leaf and branch and the leaf falls.

Had the leaves remained on branches, the leaves would have continued to drink and, once temperatures drop to freezing, the water in the tree’s veins would freeze, killing the tree.

Further, with leaves fallen, bare branches are able to carry what little snow collects on them, protecting them from being broken under the weight of the snow. So, by cutting off their food supply (leaves), deciduous trees survive winter.

The fallen leaves continue to benefit the tree through winter, spring and summer by creating a humus on the forest floor that insulates roots from winter cold and summer heat, collect dew and rainfall, and decompose to enrich the soil and nurture life.

It’s a cycle of survival, planned wisely. 

Why do leaves change color?

Chlorophyll Molecule (Wikipedia)

Leaves on deciduous trees change color in autumn from green to various hues of lime, yellow, gold, orange, red and brown because of a combination of shorter days and colder temperatures.

Throughout spring and summer, green chlorophyll (which allows trees to absorb sunlight and produce nutrients) is made and replaced constantly.

However, as days grow shorter, “cells near the juncture of the leaf and stem divide rapidly but do not expand,” reports Accuweather.com. “This action of the cells form a layer called the abscission layer.

“The abscission layer blocks the transportation of materials from the leaf to the branch and from the roots to the leaves. As Chlorophyll is blocked from the leaves, it disappears completely from them.”

That’s when vivid yellow xanthophylls, orange carotenoids and, due to a different process, red and purple anthocyanins emerge.

Orange is found in leaves with lots of beta-carotene, a compound that absorbs blue and green light and reflects yellow and red light, giving the leaves their orange color.

Yellow comes from Xanthophylls and Flavonols that reflect yellow light. Xanthophylls are compounds and Flavonols are proteins.  They’re what give egg yolks their color.

Though always present in the leaves, Carotenoids and Xanthophylls are not visible until Chlorophyll production slows.

Red comes from the Anthocyanin compound. It protects the leaf in autumn, prolonging its life. Anthocyanins are pigments manufactured from the sugars trapped in the leaf, giving term to the vernacular expression, “the leaves are sugaring up.”

The best fall color occurs when days are warm and nights are clear and cold. California’s cloudless skies and extreme range of elevations (sea level to 14,000′) provide ideal conditions for the development of consistently vivid fall color, as seen in these reports. 

The Science of Changing Leaves

Is red a defensive color? (November 22, 2018) John Poimiroo

Smithsonian.com has posted a fascinating time-lapse video of leaves transforming from chlorophyll-filled green to tones of yellow, red and brown, accompanied by an article explaining how leaves change color and some misconceptions about the process.

The video was created by Owen Reiser, a mathematics and biology student at Southern Illinois University Edwardsville. Reiser, Smithsonian.com reports, took 6,000 photos of leaves to weave together the video.

CaliforniaFallColor.com has reported previously how the change of leaf color results from the loss of chlorophyl, due to shorter days and fewer nutrients. Though, David Lee, Professor Emeritus of biological sciences at Florida International University and author of Nature’s Palette, The Science of Plant Color, says many (including us) have misreported (we won’t make the mistake again) that yellow and red leaves change the same way, when they do not.

Lee states in the Smithsonian.com article that the breakdown of chlorophyll in the leaves does reveal yellow and orange (carotenoids) hidden beneath, but that red (anthocyanin) pigments are produced within the leaves as they die.

There are two schools of thought as to why this happens. One is that the red color is a defensive measure to make the plants look an unhealthy red as the leaf dies, protecting it from plant-eating bugs and animals which are conditioned not to eat red foliage.

The other thought is that red is a form of photo protection. Horticulturist Bill Hoch, Smithsonian.com reports, believes red’s wavelength helps shield the leaf by absorbing excess light allowing the plant to more efficiently remove nitrogen from the proteins that are breaking down and send that nutrient back to tree limbs and roots, saving as much of it as possible before winter.

Whatever the cause, the result is spectacular and less than a month away from being seen in California.


Scouting Report: Siskiyou

Mt. Shasta, Autumn (File Photo)

Whenever I visit Siskiyou County, I question why it took so long to return. The county is so beautiful and loaded with tantalizing outdoor things to do that it’s a wonder it’s so lightly populated and traveled.

Siskiyou is the frosting atop California’s layer cake of spectacular places, and Mount Shasta is its grandest decoration.

What’s kept me from visiting more often has been my perception that it’s too far away. However, on a recent scouting trip up north, time melted away and anticipation built as I drove north on I-5.

Near Red Bluff, big, beautiful, frosted Mt. Shasta rose above the horizon, beckoning and reminding me why Siskiyou is so irresistible.

CaliforniaFallColor.com posts far too few reports from locations north of Shasta Lake, but when we do, they glitter with gold.

Among my favorites for fall color are the Klamath River, McCloud River, Hedge Creek, Mossbrae Falls, Faery Falls and any spot that contrasts fall color with Mt. Shasta.

Greenhorn Rd., Etna, Autumn (File Photo)

I asked Siskiyou County’s Megan Peterson where locals go when the color begins sparkling. She likes the Scott Valley where bigleaf maple populate the twisting edges of the Scott River. Good one.

Megan also likes the Gateway Trail system near Yreka. Dogwood and Bigleaf Maple are the dominant deciduous trees and part of the Foundation Trail (part of the Gateway) has tightly bunched dogwood that “put on a great show” in autumn.

Hiker Jane Cohn of Mt. Shasta City lists the Castle Lake Shore Trail, Lake Siskiyou Trail, Box Canyon Trail, Ney Springs Canyon Trail, McCloud River Fall Trail, Sisson Meadow Trail, Dunsmuir Trail, Sacramento River Trail, Pine Tree Hollow Loop, Kelsey Creek Trail and Cabin Creek as all being flanked with pockets of bold color in autumn.

Hikemtshasta.com recommends the Cliff Lake Trail and Spring Hill Trail. 

Mt Shasta Resort, Autumn (File Photo)

Then, of course, the Mt. Shasta Resort’s golf links are lined with trees that shine bright orange in autumn.

In late May, driving along the McCloud Road, dogwood were abloom with their floral white bracts, hinting at the display of yellow sure to appear once autumn arrives.

Autumn is, however, still a season away, but then don’t put off visiting, as I had. There’s just too much to see, enjoy and explore atop the state in Siskiyou County that is downright irresistible.

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Special Report: New England

Cambridge (11/8/18) Crys Black

While California and the west have experienced exceptional color this autumn, it was disappointing in the northeast.

One of the warmest summers on record, one that extended into October and that kept nights warm, was credited for delaying color development across New England. Trees remained green into October. 

Then, it rained as temperatures cooled, ruining the leaves.

California color spotter Crys Black enjoyed a trip to beantown this week and sent back these snaps of New England’s trees carrying Peak to Past Peak color.

Though the show was not New England’s typical brilliant scarlet, gold, gamboge and orange, its somber tones of marroon, burnt umber, auburn and feuille morte have a deadened dignity that remains beautiful, particularly in the soft glow of twilight. 

  • New England – Peak to Past Peak, YOU ALMOST MISSED IT.
Cambridge (11/8/18) Crys Black

Special Report: Japan

Japanese Larch, Patchy (10/19/18) Julie Kirby

5th Station, Mt Fuji, Japan (10/19/18) Julie Kirby

5th Station, Mt Fuji, Japan (10/19/18) Julie Kirby

Japan is renowned for its beautiful autumn colors. So, when color spotter Julie Kirby wrote saying she was traveling to Japan and hoped that the Japanese maple would be peaking, I encouraged her to send pictures.

She was there as fall color was at the upper end of Patchy, so the forests were not full of gold, orange, crimson and auburn. Though, her photographs show the beauty that a Japanese autumn promises.

Japanese Larch, 5th Station, Mt Fuji, Japan (10/19/18) Julie Kirby

Among the colorful trees Julie saw was the Japanese Larch, Larix kaempferi. This deciduous conifer was in the process of changing from green to yellow.

No similar deciduous conifers are native to California. Though, the Western Larch, Larix Occidentalis, grows in the northwest (bright yellow); the Subalpine Larch, Lariz lyallii, is a golden yellow native to parts of Canada and the northwest U.S.; and the Tamarack larch, Larix laricina, is native to northern Minnesota and Canada (orange-yellow).

Virginia creeper, Lake Ashi, Japan (10/19/18) Julie Kirby

Virginia creeper, Takayama, Japan (10/21/18) Julie Kirby

Just as we love Japanese maple, so too the Japanese return the favor with an affection for North American Virginia Creeper, Parthenocissus quinquefolia

Julie saw brightly draped walls of purple, maize and scarlet Virginia Creeper flourishing on Honshu (Japan’s largest island) at Takayama and Lake Ashi.


Kenrokuen Garden, Kanazawa, Japan (10/23/18) Julie Kirby

Sakura (cherry), Kanazawa, Japan (10/22/18) Julie Kirby

Curiously, Virginia creeper, growing in North America, are being eaten voraciously by invasive Japanese beetles, Popillia japonica, a specie of scarab beetle Whereas, in Japan, the beetle is not similarly destructive because they are controlled by native predators.

The Japanese are famous for their artistic gardens. Julie found beautiful trees at the Kenrokuen Garden in Kanazawa hinting of Autumn’s glory to emerge in coming weeks, Sakura, Prunus serrulata (cherry) trees now drop orange, red and golden leaves that spiral downward to reflecting ponds coursed by colorful koi fish. 

Thinking about that image inspires Autumn Haiku:

Autumn winds twirling,
Lifting leaves of gold and red,
How I love the dance!

Karen Ball

Leaves that spiral down
to still, reflective waters;
Autumn in Japan.

— John Poimiroo

  • Honshu, Japan – Patchy (10-50%)

Kenrokuen Garden, Kanazawa (10/23/18) Julie Kirby




Special Report: Odessa

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Southern California color spotter Alena Nicholas sends these images from Odessa a Ukrainian city on the Black Sea.

Odessa is the third-most populous city in the Ukraine and one of the most visited in Eastern Europe.

Alena’s images show a bit of the fall color that fills its parks, the city center and Black Sea area. The city’s innocence, playfulness and old-fashioned character is evident in her photos.

Odessa has been at the crossroads of conflicts throughout its existence. Originally a Greek city, it then became Tartar, then Ottoman, then Russian and Soviet, before being a self-governing nation and friend of the United States.

Several California cities have sister city or agreement relationships with Ukrainian cities: Sebastopol with Chyhyryn, Sonoma and Santa Rosa with Cherkassy, Davis with Uman and Santa Barbara with Yalta.

Often occupied and desired for its warm-water seaport, Odessa is called the “Pearl of the Black Sea.”

Odessa’s architecture reflects its diverse governance, though was heavily influenced by French and Italian neo-classical, art nouveau and renaissance styles during the Czarist period. That’s evident in Alena’s pictures of the city park and street scenes.

In autumn, Ukraine is beautiful to behold, as 52 percent of its trees are deciduous, including birch, aspen, maple, elm, acacia and ash. As evidenced above, Odessa loves trees and culture, with landmark plane trees shading violinists and downtown shoppers.

Odessa is the first European city to be featured by a Special Report on CaliforniaFallColor.com. When you travel to colorful fall destinations, send photos and we’ll report what you’ve seen. 

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas

Odessa, Ukraine (10/23/18) Alena Nicholas


Legends and the Land

Keddie Ridge, Plumas County (10/21/18) Jeff Luke Titcomb

All cultures pass stories and legends from generation to generation. Some are related to religious or origin beliefs, others to civil or moral codes. Some are intended as guidance to children, while others are of family or tribal history.

California native people retold many legends about land features, and it is impossible to scout for fall color without being at places that were described in these legends.

When filing a report about fall color in the Indian Valley, Jeff Luke Titcomb mentioned “Indian Head” a feature of Keddie Ridge in Plumas County that is now skirted with golden yellow maples and orange/yellow oaks, saying the Mountain Maidu people of Northeast California tell stories of its origin.

In Jeff’s picture above, rock outcroppings on the ridge resemble the face and body of a sleeping man. According to Mountain Maidu legend, an ancient giant once traveled the world measuring the depths of lakes and streams. After measuring a lake atop the ridge, he was so fatigued that he lay down to rest and fell into a deep sleep. He never awoke, and his reclining figure is seen to this day. According to Maidu elders, when he eventually awakes, it will mark the end of our time on Earth.

By learning legends, such as this, we enrich our search for fall color, gain a greater connection to the places we visit, better appreciate the cultures that preceded us, and sustain their memory.

To know more about Mountain Maidu legends that are connected to auto tours of Plumas County’s Indian Valley, CLICK HERE


Special Report: Rocky Mtn NP

Glacier Gorge Trailhead, Rocky Mtn NP (10/6/18) Cathy Tsao

Least Chipmunk, Rocky Mtn NP (10/6/18) Cathy Tsao

Beaver Ponds, Rocky Mtn NP (10/6/18) Cathy Tsao

North American Elk, Rocky Mtn NP (10/6/18) Cathy Tsao

Upper Beaver Meadows, Rocky Mtn NP (10/6/18) Cathy Tsao

Rocky Mountain National Park was my “go to” place when I was a J-school grad student at Boulder.

It was where I would go, when completing a photography project, to wind down or just be inspired.

So when Cathy Tsao a color spotter from the North Bay sent these pictures of RMNP, I just had to share them.

Cathy apologized for the “overcast and drizzly” day, but no apology was necessary, many of the photographs I treasure most from my days at CU happened on drizzly days in the national park.

Colorado has large stands of aspen that spread across similar elevations throughout the Rockies. Because of this, Colorado’s fall color all seems to peak within two weeks. So, the rush to see the trees during that tight window is intense, as is the disappointment of not getting there in time.

@RockyNPS posts photographs of the fall color and it appears the color shows very similar in timing to the High Sierra, as peak color was being reported in late September.

Colorado is famous for panoramic swaths of yellow color, though at RMNP the aspen carry red, orange, yellow and lime, similar to that seen in the Hope Valley and Eastern Sierra.

Tsao found color to be approaching Past Peak this week along the park’s Bear Lake Road and Trail Ridge Road. She was impressed to see “some hillsides absolutely blanketed with color, as in the photo taken from the Glacier Gorge trailhead.”

If Yosemite is a landscape park, Rocky Mountain is a wildlife park, famous for its bighorn sheep, North American elk, moose, lynx, wolverine and endearing chipmunks. 

  • Rocky Mountain National Park (7,800′) – Peak to Past Peak – GO NOW as YOU ALMOST MISSED IT!