Kentucky Coffee Tree

Kentucky coffee trees form thick, leathery pods that reman on the tree during the winter.

Walk down Twin Cities’ streets and look at the trees. June berries grow next to basswoods, red maples with hackberries and crab apples. The single-species plantings of the past are being replaced with a broad mix of native species and more resilient hybrids.

The Kentucky coffee tree (Gymnocladus dioicus) is one such native that’s interesting in appearance and history. The tree’s dark pods, open branch structure and scaly bark caught my eye because they differ from the smooth, gray-barked basswoods and red maples growing nearby.

The scaly, craggy bark of Kentucky coffee trees sets them apart from trees with smooth, gray bark, such as basswoods and red maples.

I didn’t think that a tree with Kentucky as part of its name would survive so far north, but it’s native to several counties south of the Twin Cities and new cultivars grow well north of the cities. It is listed as being native to Ontario, Canada, and the Central United States from Pennsylvania west to Nebraska and from Minnesota south to Oklahoma. It typically grows in small clusters because, in spite of its large seeds, it spreads mainly by forming suckers or root sprouts. The tough, impermeable seed coats result in a low germination rate. You’re more likely to find it growing on a city boulevard than in the woods. As a result, in Minnesota, the Kentucky coffee tree is listed as a “species of special concern.”

Female Kentucky coffee trees develop large green pods that darken in late summer.

The ripe seed pods contain several marble-sized seeds, which are toxic unless thoroughly cooked.

Like locust trees, the Kentucky coffee tree is a member of the pea or legume family, but its pods are large, reddish-brown, woody and thick compared to its relatives’, which are much slimmer. Whitish-green male and female flowers grow on separate trees. The fertilized female flowers form light green pods that ripen to the dark coloration in autumn. The tough pods contain several marble-sized seeds surrounded by sticky pulp and remain on the trees through winter. Native trees prefer rich, moist soil near rivers, but above the flood plain.

How did a tree in the pea family garner the name coffee tree? Early Kentucky settlers thought the seeds resembled coffee beans, but there’s no relation between the tree types. According to several sources, settlers roasted the seeds and used them to brew a coffee substitute — but don’t brew your own! They stopped this practice as soon as coffee could be imported because the beverage tastes very bitter — and unless they are thoroughly roasted, the seeds and pods are toxic!

This young Kentucky coffee tree shows the full foliage and green seed pods of summer.

Further Reading:

Minnesota Department of Natural Resources

Eloise Butler Wildflower Garden

University of Kentucky Department of Horticulture

Spring Happens All Around Us

On a recent morning, a friend looked outside and noticed the green blush beginning on trees and bushes. She recalled a teaching colleague’s comment during playground duty years ago. The colleague, a quiet woman of few words said, joyfully, “Oh, take a look! Spring is happening right before our eyes!”

Indeed it is. Thunderstorms, rain and mild temperatures coaxed baby leaves from their snug buds. They open like tiny green roses, flawless and smooth, not yet chewed upon by insects or mammals. Even on these cloudy, gray days buds and baby leaves paint the landscape in soft pastel greens and yellows. Don’t miss their fleeting, fragile beauty! They’ll quickly mature to full size and summer’s cool greens.

Maple Flowers


In Minnesota, native maple trees typically flower before bees and other pollinators are active.

Spring’s earliest flowers are popping open: gauzy crocus clusters, squill — Siberian and striped — and snowdrops that have bloomed through snow, cold and high winds for a month. They are lovely, these Eurasian transplants that paint the earth with pockets of bright color. Our native blooms are more hidden and less showy, yet are beautiful in their unflowerlike forms.

Look up at the maple trees. Easy to miss high overhead, these blossoms are small, muted and less recognizable as flowers. Each emerges from a scarlet bud coat and glitters with golden, translucent filaments tipped in auburn pollen. They remind me of minute, single-celled creatures that we might see in a drop of water under a microscope, or of the tiny squiggly animals living on a coral reef — beauty suspended in air rather than water.


Male flowers of the silver maple (Acer saccharinum) are packed with pollen for wind dispersal.


The female flowers of red maples (Acer rubrum) remind me of tiny coral reef creatures.

Oh, and even if we don’t notice the flowers overhead, if you are allergic to tree pollen, your “nose knows” that maples are blooming! Why do they disperse so much pollen? In most years, maples and a few other trees bloom before native bees and honey bees are active. The early-flowering trees depend on indirect wind pollination. Male flowers produce copious pollen to successfully fertilize female flowers on other maples.

October Yellow (Move Over, Red!)


It’s easy to focus on the “can’t miss” colors of autumn’s oaks and maples. Orange and red dominate October’s landscape.  But, look more closely: Yellow’s quiet beauty slowly swells from a few bright pockets of heart-shaped basswood leaves, to entire bluff-sides wrapped in lemon, butter and gold of birch, cottonwood, maple and hickory. Woods that were deeply shadowed and cool green just a few days ago, now glow on a sunny afternoon. The air smells good — earth, ripe seeds and the slightly tangy scent of aging leaves — all part of autumn’s final act before winter spreads its monochrome blanket.


Signs of Autumn

Grape woodbine vines (Parthenocissus inserta) weave color through an old wood pile.

The warm, windy afternoon feels summery, but there’s no denying the first signs of autumn present in the woods and fields of Pine County in East Central Minnesota. I smell the sharp, earthy scent of crisp, dry leaves. Many trees are still green, but basswoods are shedding their leaves, silver maples are going gold, and red oaks show splotches of bright color. The most colorful leaves belong to the grape woodbine vines that climb over an old wood pile and thread scarlet up the trunks of many trees.

Ripe acorns drop, swishing through leaves as they fall. Some hit hard like a rock; some bounce and tumble down the cabin roof; others plunk and splash into the water of the Snake River. Blue jays, chipmunks and gray squirrels scramble to collect and store the nuts for winter. The turf is also littered with hickory nuts, walnut husks and basswood nutlets.

Grape woodbine and lichens light up the trunk of an old silver maple tree.

The large heart-shaped leaves of basswoods, or lindens (Tilia americana), are the first to be shed this year.

A mossycup or bur oak acorn (Quercus macrocarpa); the seed of a white oak that prefers rich, moist soil and grows along the riverbank.

Eastern chipmunks (Tamias striatus) gather acorns, hickory and other nuts to eat over the winter.

Roadsides and fields offer a bounty of autumn wildflowers — native asters, tall sunflowers, bottle gentians, Black-eyed Susan’s and a few others. Bees, wasps and painted lady butterflies hang like ornaments on the blossoms and the air is heavy with their busy drone.

Mixed groups of migrating warblers hunt for insects, swinging like tiny acrobats on tree branches. The pesky gnats, mosquitos and other tiny bugs that annoy us fuel the warblers’ journey to Central America.

A bumble bee (Bombus spp.) pollinates tall sunflowers (Helianthus giganteus).

A bald-faced hornet (Dolichovespula maculate) drinks nectar from panicled asters (Symphyotrichum lanceolatum).

Painted lady butterflies (Vanessa cardui) are attracted to red clover, thistle and other autumn wildflowers.

A bladk-and-white warbler (Mniotilta varia) hunts insects in the river shallows.

In a few short weeks, all of this busy activity will disappear and the quiet of winter will descend. In the meantime, I hope for a long, warm autumn and will enjoy the changing beauty of trees, flowers, seeds and creatures. What signs of autumn do you notice?

Gray dogwoods (Cornus racemosa) develop white berries and maroon leaves in autumn. The berries are a favorite food of grouse and pheasant.


Blooming Crabs

Whatever crabapples lack in flavor, the trees make up for in year-round beauty. In early May, they scent the air with an aroma softer than lilacs or peonies. The blossoms range from bright white to pink to deep red. Many species show buds of one color and open to reveal a different hued blossom. The fruit or pomme varies in color, too, from deep red to orange and yellow. Many crabs hold their fruit through the winter, or until eaten by wildlife.

Why is such a lovely tree named a crab? Late Middle English crab or crabbe meant “fruit of the wild apple” possibly from the similar Swedish word, krabbäpple. It also connoted the sour or bitterness of the fruit. Though crabapples are bitter to the human palate, the fruit is an important source of nourishment to many mammals and birds during the winter. In the spring, native bees, such as orchard bees, collect pollen. Early butterflies drink the nectar and later in the season, the leaves provide food for caterpillars.

Scientists believe that all domestic apples originated in Kazakhstan’s mountains. But, there are three species of “wild,” or crabapples, indigenous to North America. Many others were brought here by immigrants from Europe and Asia. How does one distinguish between the two types of apples? A general rule is that wild apples (crabs) are two inches in circumference or smaller and domesticated apples are larger than two inches. Like common or domesticated apples, crabs are members of the rose family and belong to the genus ‘Malus’. Crabapple jelly is delicious if you don’t mind a little tartness! But whether or not you like the fruit, enjoy the beauty of their blossoms this spring!


May Snow

Heavy, wet snowflakes mix with apple blossoms on the first day of May in Saint Paul, MN.

It was a good rain, light-to-steady over several hours, the kind that soaks deeply into the soil and awakens late-sleeping perennials in the spring. Mid-afternoon, though the calendar showed May 1st, big, heavy snowflakes fell like icy polka dots. The blend of apple blossoms and sloppy, wet snow was a sly reminder that, in spite of increasing warmth and longer days, winter is never truly far away from those who live in the north!

The snow didn’t injure the blossoms of this more than 70-year-old Beacon apple tree, a hardy tree bred for Minnesota springs.

Winter Trees

A weathered old northern red oak (still living) has been a home to many birds and other animals.

A weathered old northern red oak (Quercus rubra) is home to many species of birds and other animals.

A tree’s beauty is easily noticed in three seasons: Spring’s first green haze of buds; summer’s rustling crown of leaves; and autumn’s smoldering colors. Winter uncovers a different kind of beauty: that of bark, interesting shapes, animal shelters and open sky — the guts of things not often seen.

A small stand of northern red oak, at our cabin along the Snake River in Pine County, MN, includes a tree that was sheared off in a summer windstorm two decades ago. Neighboring branches hide the jagged top most of the year, but in winter the scarred wood’s polished grain and shape are revealed, along with hidden nesting cavities. Squirrels, great-crested flycatchers, red-bellied woodpeckers and most recently, pileated woodpeckers have nested and raised their young in this red oak.

Crabapple trees (Malus) provide food for many birds and add winter color.

Crabapple trees (Malus) provide food for many birds and add winter color.

Crabapple trees, especially those with long-lasting fruit, add warm crimson to the stark black and white landscape. Their small shapes and curving branches remind me of bonsai trees. By late spring, most of the plump fruit will be consumed by cedar waxwings and robins.

The bark of river birch (Betula nigra) is multicolored and has a shredded texture.

The bark of river birch (Betula nigra) is multicolored and has a shredded texture.

Bark patterns and colors are more pronounced in winter with fewer distractions from the rest of the plant world. One of my favorites is the papery bark of the river birch. The colors range from soft brown to salmon, pink and ivory. The bark shreds and flutters in the wind. Paper birch bark (Betula papyrifera) is pretty too, especially at sunrise and sunset when low rays add blush to the tips of twigs and branches.

White spruce (Picea glauca) and other evergreens shelter many creatures.

White spruce (Picea glauca) and other evergreens shelter many creatures.

The white spruce has grayish-red bark with a rough mosaic-like texture. Its evergreen branches shelter cardinals, kinglets, juncos and chickadees. At the end of winter, new burgundy cones appear, like tiny ornaments, on the tips of branches.

New cones form on a white spruce.

New cones form on a white spruce.

Winter trees reveal the hidden face of nature — textures, hues, patterns weathered and worn — and more open sky to view the moon, stars and urban sunsets; beauty to the eye that looks carefully. What do you see?

Winter sunset over Saint Paul, MN, on Feb. 22, 2017.

Winter sunset over Saint Paul, MN, on Feb. 22, 2017.


The Ancient Ginkgo Tree

Pollution and disease-resistant ginkgo trees are planted as boulevard trees in St. Paul, MN.

Pollution and disease-resistant ginkgo trees are planted as boulevard trees in St. Paul, MN.

In mid-November when most trees are bare, a ginkgo tree lit by the sun is a golden sight. Until last Friday’s heavy rain, wind and snow, the ginkgoes were beautiful this year. Ginkgoes (Ginkgo biloba) are also called maidenhair trees because their leaves resemble those of the maidenhair fern. The leaves remind me of delicate Asian fans — cool green in summer, and in autumn, bright yellow mellowing to a deep gold.

I saw my first ginkgo on a beautiful fall day in the late 1970s on the campus of St. Catherine University in St. Paul, Minn. I’d not heard of a ginkgo and never guessed that an ancient tree native to China would become a common boulevard tree in the Twin Cities. Ginkgoes do well in USDA plant hardiness zones 3-8, and many are planted in urban areas because they tolerate air pollution and the corrosive de-icing salt used on streets in northern winters.

The ginkgoes' beautiful leaves remind me of Asian hand fans.

The ginkgo’s beautiful leaves remind me of Asian hand fans.

The word ginkgo means “silver fruit” or “silver apricot.” Fossils of ginkgo trees precede dinosaurs, dating back 270 million years to the Jurassic period. They lived with such creatures as dragonflies, trilobites, many types of reptiles, and such plants as mosses and conifers. In comparison, the oldest fossilized maples are about 100 million years old, and trees similar to modern oaks arose nearly 35 million years ago. Like other ancient plants, ginkgoes are non-flowering.  They reproduce similarly to ferns and algae. The male tree produces a pollen cone and the female tree a flowerless ovule. Each pollen grain contains two motile sperm. When the pollen grains reach the ovule, a tiny droplet of liquid must be present for the sperm to swim to and fertilize the ovule to produce the seed.

The oldest living ginkgo in China is thought to be more than 3,500 years old. A testament to the species’ resilience is its survival of Earth’s many climatic changes deadly to other organisms. In modern times, six ginkgoes survived the atomic bombing of Hiroshima, Japan. Temples and other buildings were destroyed. The ginkgoes were damaged and burned, but leafed out the following year and are still alive today about .6 miles from the impact site.

Ginkgo leaves change from bright yellow to deep gold as they age.

Ginkgo leaves change from bright yellow to deep gold as they age.

So, with their beauty, long life, strength and stamina, what’s not to like about ginkgoes? Unfortunately, the outer coat of the ginkgo seed reeks. When the seeds drop from the trees and are crushed on the sidewalk and street, they create a terrible stench – some compare it to the odor of rancid butter or vomit. Only the female tree produces seeds, so city planners and residents often plant male trees. However, if the male tree was grafted to female rootstock, the mature tree sometimes produces seeds. In China and Japan, the seeds are peeled and used in many types of cuisine. Enjoy the beautiful ginkgo, but don’t walk through the messy, malodorous seeds!

October Gold and Blue

White oaks shine against a cloudless October sky.

Bur oaks (Quercus macrocarpa) shine against a cloudless October sky.

The fleeting season of gold and blue arrived in central Minnesota last week. The golden hues of bitternut hickory, bur oak, aspen and ash glow against a sky the color of a newly opened morning glory — a shade unique to autumn. Along the Snake River in Pine County, MN, the steely blue-gray wings of a great blue heron swoop over the sparkling water.

A great blue heron (Ardea herodias) swoops over the Snake River in east central Minnesota.

A great blue heron (Ardea herodias) swoops over the Snake River in east central Minnesota.

Sky blue morning glories continue to bloom in October.

Heavenly blue (Ipomea purpurea) morning glories continue to bloom in October.

Closer to the ground, the last of the powder-blue bottle gentians and asters — some with center disks as bold as the sun — bloom among the grasses. Fallen aspen leaves accent walkways, and the heart-shaped leaves of the carrion flower vine wind their tendrils skyward. In a few days, this lovely combination will dampen down to more muted tones, the gentle softness that insulates the earth for winter’s palette of black and white.

Bottle gentian blooms (Gentiana andrewsii) turn dark and dry out as their seeds mature.

Bottle gentian blooms (Gentiana andrewsii) turn dark and dry out as their seeds mature.

Asters (Symphyotrichum novi-begii) provide nectar to these hoverflies and many other autumn insects.

Asters (Symphyotrichum novi-belgii) provide nectar to these hoverflies, or syrphids, and many other autumn insects.

Aspen leaves and moss decorate a walkway at our cabin.

Quaking aspen leaves (Populus tremuloides) and moss decorate a walkway at our cabin.

The heart-shaped leaves of the carrion flower (Smilax herbacea) add light and color to the October woods.

The heart-shaped leaves of the carrion flower vine (Smilax herbacea) add light and color to the October woods.