Blackhaw Viburnum – A Subtle Beauty

Blackhaw Viburnum (Viburnum prunifolium)

Blackhaw Viburnum (Viburnum prunifolium)

Blackhaw Viburnum (Viburnum prunifolium) begins to bloom about a week after Flowering Dogwood (Cornus florida), its profuse rounded clusters of creamy white flowers visited by a variety of bees, flies and butterflies for their nectar and pollen.  Although less well known than some of its woodland neighbors, such as Dogwood and Redbud, Blackhaw Viburnum’s subtle beauty is a common and essential element of the forest’s palette in spring.

Blackhaw Viburnum (Viburnum prunifolium)

Blackhaw Viburnum (Viburnum prunifolium)

Spring Azure butterfly caterpillars may eat the flowers or buds of many woody plant species, including the viburnums.

Spring Azure

Spring Azure

Hummingbird Clearwing moth caterpillars may feed on their leaves.

Hummingbird Clearwing nectaring on Wild Bergamot (Monarda fistulosa)

Hummingbird Clearwing nectaring on Wild Bergamot (Monarda fistulosa)

In their later development stages, even Baltimore Checkerspot caterpillars may migrate from the leaves of their preferred food plant, Turtlehead (Chelone glabra) to eat viburnum leaves.

Baltimore Checkerspot

Baltimore Checkerspot

The caterpillars may be lucky enough to attain adulthood, or they may become food for another animal somewhere along the way.  Caterpillars are an important source of food for many animals, but especially for birds.  It can take thousands of caterpillars to feed a hungry brood of young Chickadees or Titmice.

Tufted Titmouse

Tufted Titmouse

If Blackhaw Viburnum’s spring visitors successfully pollinate its flowers, dark blue fruits (called drupes) are produced, maturing in fall.

Blackhaw Viburnum (Viburnum prunifolium) fruit

Blackhaw Viburnum (Viburnum prunifolium) fruit

Chipmunks, squirrels and many bird species, including Hermit Thrush, Cardinals, Bluebirds and White-throated Sparrows, are among those that eat the fruit.

Northern Cardinal

Northern Cardinal

Blackhaw Virburnum can be single or multi-stemmed, and grows to a maximum height of about 15-25 feet (4.6-7.6 meters).  It tends to grow taller when single-stemmed.  Its natural habitat is generally medium to dry upland areas, even growing in rocky soil, like the Sourland Mountains of New Jersey where I live.  Its range is from New York to Michigan and Wisconsin in the north, to the south from Texas to Georgia.

Blackhaw Virburnum makes a great landscape plant.  Look for it blooming in a forest near you, or better yet, add it to your garden and enjoy it and its visitors throughout the seasons.

Blackhaw Viburnum (Viburnum prunifolium)

Blackhaw Viburnum (Viburnum prunifolium)

 

Resources

Cech, Rick; Tudor, Guy.  Butterflies of the East Coast.  2005.

Wagner, David L.;  Caterpillars of Eastern North America, 2005.

http://www.illinoiswildflowers.info/trees/plants/blackhaw.htm

American Beech

American Beech (Fagus grandifolia)

American Beech (Fagus grandifolia)

It can be surprising  to see leaves clinging to deciduous trees in mid-winter.  In eastern North America, some oak species and American Hophornbeam (Ostrya virginiana) may retain their leaves but American Beech (Fagus grandifolia) trees are among the most conspicuous to do so.  By January its leaves are bleached to a papery pale tan, catching the bright winter light while fluttering in the winter wind.  The leaves look delicate, but give one a tug and you’ll see how tenaciously they adhere to their branches.  American Beech leaves typically stay on the trees until early spring, withstanding the effects of even ice and snow.

American Beech (Fagus grandifolia), in March

American Beech (Fagus grandifolia), in March

Why do American Beech and other trees keep some of their leaves in winter?  There are many theories:  the dry leaves may be a deterrent to winter browsing by deer, moose and other mammals;  holding some of the leaves until spring may be the trees’ way of time-releasing some nutrients for recycling into the soil;  the leaves may funnel more snow melt to the tree’s root system.  But no one knows for certain what caused this trait.

The smooth, pale gray bark is an unmistakable characteristic of American Beech, often tempting passers-by to carve their initials.  A more interesting possibility is a sighting of animal ‘tracks’ – claw marks from animals that may have climbed the tree at some point.

Animal 'tracks' on American Beech (Fagus grandifolia)

Animal ‘tracks’ on American Beech (Fagus grandifolia)

Trees are susceptible to frost cracks in winter, caused by warming from the low-angled rays of the winter sun, followed by rapid cooling when the sun sets or disappears behind a cloud.  Both the bark and the wood it encompasses expand in the warm sun, but the bark may cool more quickly than the wood when the sun disappears, causing lengthwise cracks to occur in the bark.  If temperatures are warm enough, portions of the inner bark may become active, only to be killed if a rapid refreeze occurs.  American Beech evolved to minimize the harsh effects of the sun by having light-colored bark that reflects the sun’s rays.  The winter leaves may provide an additional layer of protection from the warm sunlight.

American Beech’s long, sharply pointed copper-colored buds are another distinctive winter identification feature.

American Beech (Fagus grandifolia) buds

American Beech (Fagus grandifolia) buds

As spring approaches, American Beech buds grow longer and plump, eventually opening to reveal newly unfurling leaves, accordion pleated and hairy as they first emerge.  The long silky hairs are an adaptation to make the new leaves less appealing to the many species of hungry caterpillars and other insects that may eat the leaves later as the hairiness dissipates.

Newly unfurled leaves of American Beech (Fagus grandifolia)

Newly unfurled leaves of American Beech (Fagus grandifolia)

According to Bringing Nature Home by Douglas Tallamy, American Beech provides food for the caterpillars of over 100 species of butterflies and moths.  Among them is the Early Hairstreak butterfly, a rare species found in deciduous or mixed woodlands from the maritime provinces of Canada to northern Michigan and Wisconsin through the Appalachians to Tennessee and North Carolina.  Early Hairstreak caterpillars can only eat the leaves of American Beech and Beaked Hazelnut (Corylus cornuta).  The presence of caterpillars attracts predatory insects and arachnids to feed on them, including many species of spiders, wasps, ants and flies.  These insects are beneficial to the trees, because they help keep the caterpillar population in check.

In addition to butterfly and moth caterpillars, a few of the insects that use American Beech include Leaf-footed Bugs,

Leaf-footed Bug (Acanthocephala species) on American Beech (Fagus grandifolia)

Leaf-footed Bug (Acanthocephala species) on American Beech (Fagus grandifolia)

leaf-rollers,

Insect shelter, likely leaf-rolling weevil nest

Insect shelter, likely leaf-rolling weevil nest

and Woolly Beech Aphids.

Woolly Beech Aphids (Phyllaphis fagi)

Woolly Beech Aphids (Phyllaphis fagi)

The Woolly Beech Aphids’ honeydew in turn attracts other insects who eat it, including wasps and ants.

Ants harvesting Woolly Beech Aphid Honeydew

Ants harvesting Woolly Beech Aphid Honeydew

Ants help protect the tree from the insects that feed on its leaves, by aggressively attacking them.

The Harvester butterfly also feeds on the Woolly Beech Aphid’s honeydew, although its first choice is Wooly Alder aphids.  The Harvester’s caterpillars eat the aphids themselves.

Harvester Butterfly

Harvester Butterfly

A non-native scale insect (cryptococcus fagisuga) introduced through the nursery trade on European Beech threatens the health of American Beech by providing an opening in the bark that together with a fungus enables beech bark disease.  This is a good example of the importance of using native plants in your own garden, and the danger of using introduced exotic plants.

There is a fungus species that grows exclusively on the Woolly Beech Aphid’s honeydew, a sooty mold descriptively named Beech Aphid Poop-eater (Scorias spongiosa).  Some studies have shown that leaves covered in sooty molds are more effective at removing pollution from the air than other leaves are.

Beech Aphid Poop-eater (Scorias spongiosa)

Beech Aphid Poop-eater (Scorias spongiosa)

Oyster (Pleurotus ostreatus) and Burnt-Orange Bolete (Tylopilus ballouii) mushrooms, both edible, are among the other fungi that may be found on or near American Beech.

American Beech develops natural cavities that provide nesting sites for cavity nesting birds like Titmice, Chickadees, Woodpeckers and Nuthatches, all of whom rely on insects for a large part of their diet, and will help protect the tree from insect leaf-eaters.  Chipmunks, squirrels, porcupines and other mammals also take advantage of the natural shelter American Beech offers.

Gray Squirrel in cavity of American Beech

Gray Squirrel in cavity of American Beech

Other birds, like the Wood Thrush below, may nest on the limbs of American Beech, using some of the previous year’s fallen leaves as nesting material.

Wood Thrush on her nest in an American Beech. Some old Beech leaves have been used as nest material.

Wood Thrush on her nest in an American Beech. Some old Beech leaves have been used as nest material.

American Beech’s fallen leaves may offer insect protein for ground-feeders like the Ovenbird.

Insect nest on fallen American Beech leaf

Insect nest on fallen American Beech leaf

Ovenbird in American Beech

Ovenbird in American Beech

Beechdrops (Epifagus virginiana) depends on American Beech for its survival, since it gets its food from the tree’s roots.  Look for the flowers in late summer or early fall, and the brown seed capsules throughout the winter.

Beechdrops (Epifagus virginiana) flowers

Beechdrops (Epifagus virginiana) flowers

Beechdrops (Epifagus virginiana) in winter

Beechdrops (Epifagus virginiana) in winter

American Beech flowers are wind pollinated, with separate male and female flowers both on the same plant.  They bloom as the leaves are opening.

Male flowers of American Beech (Fagus grandifolia)

Male flowers of American Beech (Fagus grandifolia)

Nuts are produced if the flowers are successfully pollinated, usually 2 or 3 three-sided nuts per husk.

American Beech (Fagus grandifolia) nuts

American Beech (Fagus grandifolia) nuts

The nuts are a source of high protein and fat for mammals and birds, including red, gray and flying squirrels, chipmunks, bears, Blue Jays, Tufted Titmice, Wild Turkey, and Ruffed and Spruce Grouse.

Tufted Titmouse eating American Beech nut

Tufted Titmouse eating American Beech nut

Nothing goes to waste in nature, so an empty beechnut husk may be reused as a shelter by an insect.

Insect nest in husk of American Beech

Insect nest in husk of American Beech

As the nights get longer and the temperatures drop in the fall, the American Beech begins to prepare for winter.  The leaves gradually stop producing chlorophyll, which reduces the green color visible in the leaves, revealing the yellows and oranges of carotenes, and the brown tannins, .

American Beech (Fagus grandifolia) leaf in fall

American Beech (Fagus grandifolia) leaf in fall

American Beech is native in moist woodlands in the eastern United States and Canada.  The bounty of insects supported along with its nutritious nuts makes it one of our most valuable tree species for wildlife.

Golden-crowned Kinglet in American Beech

Golden-crowned Kinglet in American Beech

 

Resources 

Cech, Rick; Tudor, Guy.  Butterflies of the East Coast.  2005.

Eastman, John.  The Book of Forest and Thicket.  1992.

Eaton, Eric R.; Kauffman, Ken.  Kaufman Field Guide to Insects of North America.  2007.

Lincoff, Gary H.  National Audubon Society Field Guide to North American Mushrooms. 1981

Rhoads, Ann Fowler; Block, Timothy A.  The Plants of Pennsylvania.  2007

Tallamy, Douglas W.  Bringing Nature Home, 2007,

Wojtech, Michael.  Bark A Field Guide to Trees of the Northeast.  2011.

USDA NRCS Plants Database

Tom Volk’s Fungi

iNaturalist.org
http://www.inaturalist.org/taxa/144013-Scorias-spongiosa

Butterflies and Moths of North America http://www.butterfliesandmoths.org/species/Erora-laeta

Illinois Wildflowers
http://www.illinoiswildflowers.info/trees/plants/am_beech.htm

Penn State Extension Natural Resources
http://extension.psu.edu/natural-resources/forests/news/2012/winter-leaves-that-hang-on

Northern Woodlands
http://northernwoodlands.org/articles/article/why-do-some-leaves-persist-on-beech-and-oak-trees-well-into-winter

Invasive.org
http://www.invasive.org/browse/subinfo.cfm?sub=300

 

Maple-leaf Viburnum

Maple-leaf (or Maple-leaved) Viburnum (Vibernum acerifolium) is spectacular this fall, with colors ranging from pale pink to deep magenta,

Maple-leaf Viburnum (Vibernum acerifolium)

Maple-leaf Viburnum (Vibernum acerifolium)

often with washes of blue and purple.

Maple-leaf Viburnum (Vibernum acerifolium)

Maple-leaf Viburnum (Vibernum acerifolium)

The combination of decreasing hours of daylight, the increasing length of darkness, and cool nighttime temperatures is nature’s signal that it’s time to prepare for winter. Plants gradually stop producing chlorophyll, which is responsible for the green color visible in the leaves during the growing season. The absence of chlorophyll reveals the colors of other chemical compounds present, like the yellows of xanthophylls, oranges of carotenes, and browns of tannins.

Many days this fall have been warm and sunny.  Nights have been cool with temperatures often in the low to mid 40s (4 – 8°C).  These conditions enable deciduous trees and shrubs to continue to produce sugars in their leaves during the day.  Some of the sugars combine with minerals obtained from the soil to manufacture anthocyanins, the chemicals that cause the red, blue and purple colors in the leaves.  The decreasing number of daylight hours combined with the cool temperatures signal the plant to stop nutrients from moving into the trees’ circulatory system as the leaves prepare to detach from the plant.  These chemical compounds are trapped in the leaves, resulting in the colorful fall display.

Maple-Leaved Viburnum (Viburnum acerifolium) with fruit

Maple-Leaved Viburnum (Viburnum acerifolium) with fruit

Fleshy, dark blue, berry-like fruits called drupes accompany the colorful leaves. Each drupe contains a single seed enclosed by a stony casing or pit, like a peach.  For many birds and other animals, the fleshy fruit is an enticement to dine in the coming weeks.   Maple-leaf Viburnum and many other plants have evolved to produce such fruits in order to enlist animals as partners in dispersing their seeds.  The animal consumes the fruit, passing the seed through its digestive system, and depositing the seed accompanied by other nutrients.  White-throated Sparrows,

White-throated Sparrow

White-throated Sparrow

Cardinals,

Northern Cardinal

Northern Cardinal

and Hermit Thrush, as well as chipmunks and squirrels are among those who consume the fruits and disperse the seeds.

Spring or Summer Azure butterflies may lay eggs on the flower buds of this and many species of viburnums, dogwoods and other shrubs.

Summer Azure

Summer Azure

After hatching from the eggs, the butterfly’s caterpillars feed on the flower buds. That is, they do if they manage to avoid being eaten by a predator like a bird, a spider, or another insect.

Maple-leaf Viburnum (Vibernum acerifolium) in bud. Can you spot the two spiders waiting patiently for an unsuspecting caterpillar or other victim?

Maple-leaf Viburnum (Vibernum acerifolium) in bud. Can you spot the two spiders waiting patiently for an unsuspecting caterpillar or other victim?

Plenty of flowers survive the feeding frenzy to provide a beautiful summer display. Several species of native bees, flies and other insects visit the flowers for nectar, providing essential pollination services that result in the fall fruits.

Maple-leaf Viburnum (Vibernum acerifolium) in flower. Look for the ants who are visiting the flowers for nectar. They would also be happy to find a caterpillar.

Maple-leaf Viburnum (Vibernum acerifolium) in flower. Look for the ants who are visiting the flowers for nectar. They would also be happy to find a caterpillar.

Maple-leaf Viburnum is a great alternative to the non-native, invasive Burning Bush (Euonymus alatus), which is often planted in formal landscapes for its fall foliage.  Maple-leaf Viburnum offers an equally attractive, and more nuanced display.  More importantly, it provides food and shelter for the insects, birds and other animals that share its territory.

Maple-leaf Viburnum (Vibernum acerifolium)

Maple-leaf Viburnum (Vibernum acerifolium)

Maple-leaf Viburnum is a woodland understory shrub native to the eastern United States, and Quebec and Ontario provinces. If you live within its natural range, go for a walk in the woods near you to see if you can spot it.  Then think about adding it to your own landscape to guarantee a view of this gorgeous shrub.

Maple-leaf Viburnum (Vibernum acerifolium)

Maple-leaf Viburnum (Vibernum acerifolium)

For more information on fall foliage colors, see Nutritious Fall Foliage: What Makes Fall Leaves So Colorful?

Resources

Capon, Brian. Botany for Gardeners.  2005

Cech, Rick; Tudor, Guy. Butterflies of the East Coast.  2005.

Glassberg, Jeffrey. Butterflies through Binoculars A Field Guide to Butterflies in the Boston-New York-Washington Region.  1993.

Illinois Wildflowers

 

‘Will Work for Food’ – Extrafloral Nectaries

Wild Senna (Senna hebecarpa, S. marylandica) has so many stories to tell!  This tall, herbaceous plant has flowers that are unusual for a member of the Pea (Fabaceae) family.  Rather than curling to form the banner, wings and keel that are common Pea family characteristics,

Everlasting Pea (Lathyrus latifolius) with skipper

Everlasting Pea (Lathyrus latifolius) with skipper

Wild Senna’s petals are open and distinct.

Wild Senna (Senna hebecarpa) with Bumble Bee. Note the pollen on her rear legs.

Wild Senna (Senna hebecarpa) with Bumble Bee. Note the pollen on her rear legs.

Wild Senna’s flowers have another somewhat unusual feature, or more accurately, they lack a feature, nectaries, that many flowers have.  Many plant species have evolved to entice pollinators to their flowers by providing a reward of nectar in exchange for their visits. In spite of the lack of nectar, Wild Senna is pollinated by bees, primarily Bumble Bees but also Sweat Bees (Halictid species).  They visit the flowers for their pollen, a highly nutritious food that contains protein, carbohydrates, fats, vitamins and minerals; plenty of incentive for a bee to visit even without nectar.  Alerted to the possibility of food by the colorful yellow flowers, the adult bees come to dine on pollen and to harvest some to bring back to their nests for their larvae.

Many plant species have evolved to produce chemical compounds whose primary purpose is to protect the plant from being eaten by making it bitter, distasteful or even toxic to potential consumers.  Wild Senna is a species that has adapted to use this defense.  Both the leaves and fruits (seed pods) contain anthraquinones, which are powerful laxatives.  Often people take advantage of the protective chemicals that plants produce by finding medicinal uses for them. In the case of the Senna species, the laxative is used for treating constipation.

These chemicals are a very effective deterrent to many animal species that eat plants (herbivores).  Even in areas where there is severe deer pressure, it’s unusual to see Wild Senna browsed.  But this strategy is not effective against all potential herbivores.  There are some butterflies and moths, including the Cloudless Sulphur,

Cloudless Sulphur caterpillar on Wild Senna (Senna hebecarpa)

Cloudless Sulphur caterpillar on Wild Senna (Senna hebecarpa)

Sleepy Orange,

Sleepy Orange butterfly

Sleepy Orange butterfly

and the Common Tan Wave, whose caterpillars are able to eat the leaves or other parts of Wild Senna.  These insects have evolved to specialize on these and other closely related plants, without being harmed by the chemicals that are toxic to other species.

Which brings us to an interesting back-up strategy Wild Senna employs for protection.  Wild Senna has extrafloral nectaries, a nectar source separate from the flowers. They are positioned on the leaf petioles (stems) near their attachment to the primary plant stem and adjacent to the flower buds.  Why would a plant species offer nectar if it’s not a lure for pollinators?  It takes energy and resources to produce nectar.  What’s in it for the plant to provide this service?  Who feeds here?

The egg-shaped bump is an extrafloral nectary on a leaf stem of Wild Senna (Senna hebecarpa)

The egg-shaped bump is an extrafloral nectary on a leaf stem of Wild Senna (Senna hebecarpa)

Wild Senna’s extrafloral nectaries attract a variety of visitors, many of them beneficial members of the ecosystem.  The Sweat Bee below may have stopped here before or after visiting Wild Senna flowers for their pollen.

Sweat Bee feeding at an extrafloral nectary on Wild Senna (Senna hebecarpa)

Sweat Bee feeding at an extrafloral nectary on Wild Senna (Senna hebecarpa)

Many lady beetle species, including the Seven-spotted Lady Beetle pictured here, help to keep the aphid population in check.

Seven-spotted Lady Beetle feeding at an extrafloral nectary on Wild Senna (Senna hebecarpa)

Seven-spotted Lady Beetle feeding at an extrafloral nectary on Wild Senna (Senna hebecarpa)

This jewel-like creature is a Perilampid wasp, one of several parasitic wasps that specialize on various insect species as their prey, including some other parasitites.

Perilampid wasp feeding at an extrafloral nectary on Wild Senna (Senna hebecarpa)

Perilampid wasp feeding at an extrafloral nectary on Wild Senna (Senna hebecarpa)

For Wild Senna, ants are probably the most beneficial visitor to this nutritious food source.

Ant feeding at an extrafloral nectary on Wild Senna (Senna hebecarpa)

Ant feeding at an extrafloral nectary on Wild Senna (Senna hebecarpa)

Sugary substances like nectar are important food for ants.  But protein and other nutrients available from insects (including caterpillars) are also an essential part of the diet of most ant species.  Ants that are enticed to visit Wild Senna for its nectar can also hunt for and eat the insects that may be consuming the leaves or buds of the plant.  The placement of the nectaries between the leaf blade and flower buds is an advantageous location for protecting both plant parts.

Ant with caterpillar prey

Ant with caterpillar prey

You might think of the ants as an army of mercenaries paid in nectar to guard the plant, with as many caterpillars and other herbivores as they can catch as a bonus.  Ants will work for food!

Related Posts

Sleepy Orange Butterflies Overwintering in Pennsylvania

Cloudless Sulphurs are on the Move

Resources

USDA NRCS Plant Database http://www.plants.usda.gov/factsheet/pdf/fs_sehe3.pdf

Illinois Wildflowers http://www.illinoiswildflowers.info/savanna/plants/wild_senna.htm

Marshall, Stephen A.  Insects Their Natural History and Diversity.  2006.

Waldbauer, Gilbert.  What Good Are Bugs?.  2003.

In Praise of Black Walnut Trees

If you go for a walk in the woods any time soon, you may still encounter black walnuts or the remains of their hulls on the ground.

Fallen Black Walnuts

Fallen Black Walnuts

The nuts usually remain on the tree until after the leaves fall, reminding me of a Charlie Brown Christmas tree.  Then all the nuts fall within a short time of each other.  These nuts are sweet tasting and highly nutritious.  Studies show that eating them helps prevent cardiovascular disease, diabetes and cancer.  Walnuts have as much protein as an equal weight of beef, but they also contain essential fatty acids that are necessary for healthy brain development and function.  Any aging brains out there?  Eat walnuts!

Black Walnut (Junglans nigra)

Black Walnut (Junglans nigra)

Mammals other than humans like them, too: squirrels, mice and voles, for example.

Eastern Gray Squirrels eat and help disperse Walnuts

Eastern Gray Squirrels eat and help disperse Walnuts

Red Squirrels also enjoy many tree nuts, including Walnuts

Red Squirrels also enjoy many tree nuts, including Walnuts

These animals aid in the spread of Walnut trees when they overlook some of the nuts they have hidden away for later use, effectively planting them.

In turn, these animals are food for larger animals, like fox

Red Fox

Red Fox

and raptors.

Red-shouldered Hawks, as well as most other raptors, hunt and eat small mammals

Red-shouldered Hawks, as well as most other raptors, hunt and eat small mammals

According to Douglas Tallamy in Bringing Nature Home, the leaves of Black Walnut (Juglans nigra) trees and the closely related Butternut (Juglans cinerea) provide food for the caterpillars of over 100 species of moths and butterflies, including Luna Moths and Banded Hairstreaks.

Banded Hairstreak on Butterflyweed. Their caterpillars feed on the leaves of Black Walnut and other woody species

Banded Hairstreak on Butterflyweed. Their caterpillars feed on the leaves of Black Walnut and other woody species

The Walnut Caterpillar specializes on Black Walnut and relatives such as Butternut.  This means the leaves of these trees are the only food these caterpillars can eat.

Walnut Caterpillar (Datana integerrima)

Walnut Caterpillar (Datana integerrima)

Since they are an important source of food for birds, not all caterpillars will see life as an adult butterfly or moth.

Tufted Titmouse

Tufted Titmouse

Black Walnut trees have a reputation for not playing well with other plants. That is, many plants won’t grow successfully in close proximity (within the drip-line or reach of the roots) of a Black Walnut. The reason is more complex than shade and competition for water.  Black Walnuts contain juglone, which is an anti-fungal chemical.  In order to derive nutrients from the soil, the vast majority of plants partner with underground mycorrhizal fungi (think mushroom, not the mold in your shower).  Unless the fungi on which the plant depends is resistant to juglone, or the plant doesn’t require this partnership to obtain its nutrition, that plant won’t do well.  Of course, some plants and their fungi partners have evolved in exactly this way.  Click here for some suggestions from The Mortem Arboretum for plants that can co-habit successfully with Black Walnut trees.

It’s of benefit to Black Walnut trees to produce juglone, since it does reduce competition for resources, and protects the trees from fungal invaders that might do them harm. Juglone also has sedative properties that may aid animals in dormancy. It can even have a calming effect on people.

Black walnut trees contain another compound called ellagic acid in both their nuts and leaves. This compound is thought to help prevent cancer in people who consume the nuts. The ellagic acid in the leaves is effective in removing carcinogenic hydrocarbons from the air, helping to reduce the effects of air pollution.

As if that weren’t enough, Black Walnut’s wood is valuable for furniture and cabinet making, and the nut hulls can be used to make a dye.

Black Walnut with hull partially removed

Black Walnut with hull partially removed

These are just some of the known benefits of Black Walnut trees.  Just imagine what we don’t know yet!  No wonder ‘juglans’ is sometimes translated as ‘nut of Jupiter’, or ‘nut of the gods’.

Black Walnut Tree (Juglans nigra)

Black Walnut Tree (Juglans nigra)

Resources

Beresford-Kroeger, Diana.  Arboretum America: A Philosophy of the Forest.  2003

Eastman, John. The Book of Forest and Thicket. 1992.

Tallamy, Douglas W.  Bringing Nature Home.  2007

Wagner, David L.  Caterpillars of Eastern North America.  2005.

Butterflies and Moths of North America

Natural History Museum Database of Leipidoptera Hostplants