A Dose of Spring

One thing we can still do while keeping a safe distance from other humans during the Covid-19 virus outbreak is to go outside for a walk.  It’s a great boost to your immune system, and contributes to an overall feeling of well-being.  If you go for a walk in a natural area, it’s especially beneficial.

Swan Creek, Rockhopper Trail, West Amwell Twp. NJ

Life goes on for the other species in the world while we humans are focused on the virus. Here are some animals and plants you might see if you go for a walk in my neighborhood in the mid-Atlantic United States.

Every morning now I hear Wrens, Cardinals, Titmice and other birds singing.  For several weeks Carolina Wren couples have been out shopping for real estate, looking for a good location to build a nest for the upcoming season.  These birds nest in cavities, usually from three to six feet off the ground.  A stump with a pre-made cavity like the one that the couple in the photos below is inspecting looks like very a very desirable property.

Carolina Wrens investigating a nesting site.

Carolina Wren investigating a fallen log with a natural cavity as a possible nesting site.

Carolina Wren standing watch at a possible nesting site.

While walking in the woods, you might hear a chorus of male wood frogs calling from a vernal pool, or see a mass of eggs that resulted from successful wood frog mating.

Male Wood Frogs

Wood Frog

Wood Frog egg mass

When temperatures are warm, bees and some butterflies may be active.  Even when spring temperatures are cooler, flies are active.

Greenbottle Fly (Lucilia sericata). This adult fly can be an effective pollinator, while its larvae are crime scene investigators’ friends, consuming dead rotting flesh or other decaying matter, a task that never goes out of season. The presence of these insects’ larvae can help determine time of death of a corpse.

Fly, unidentified.

Winter was unusually warm where I live in New Jersey.  As a result, the spring bloom season is about 3-4 weeks earlier than normal.  (This is a bit alarming, but since we have enough to worry about right now, I’m just going to focus on enjoying it.) With each passing day, more and more buds break and flowers bloom.

Leatherwood (Dirca palustris) is an early blooming shrub whose flower buds come with their own ‘fur’ coat, just in case the temperatures take a tumble. If the temperatures are warm, a lovely fragrance that even humans can detect wafts many feet away from the flowers.  When the air temperature is cooler, you can still catch the fragrance if you bring your nose right up to a flower and sniff.

Leatherwood (Dirca palustris). Bud scales act as a furry hood that protect the flowers.

The sunburst-like flowers of Spicebush (Lindera benzoin) are blooming, beckoning pollinators to visit, and promising fruit for birds in the fall.

Spicebush (Lindera benzoin) blossom, male. Spicebush have male and female flowers on separate plants.

Hepatica, like Leatherwood, wears fur for warmth and to deter herbivores.  Depending on where you live, two species are possible, Round-lobed Hepatica (Anemone americana syn: Hepatica nobilis obtusa, Hepatica americana) and Sharp-lobed Hepatica (Anemone acutiloba syn: Hepatica nobilis acuta, Hepatica acutiloba).

Hepatica in bloom

The earliest of the Trilliums to blossom, Snow Trillium (Trillium nivale), has entered its short bloom season.  As you might guess, it is named for the fact that its flowers may open when snow is still present.  The Latin name nivale means ‘snow white, or growing near snow’.

Snow Trillium (Trillium nivale)

Bloodroot (Sanguinaria canadensis) has opened its blossoms, hoping for insect visitors to help it with cross-pollination, but if all else fails it will self-pollinate.

Bloodroot (Sanguinaria canadensis)

The lovely Dutchman’s Breeches (Dicentra cucullaria) is just starting to bloom, luring Bumble Bees to be their pollination facillitators.  This plant’s delicate appearance gives no hint of its narcotic-packed foliage, a reliable deterrent to herbivores that would otherwise be tempted to eat it.

Dutchman’s Breeches (Dicentra cucullaria)

The first Spring Beauty (Claytonia virginica) flowers are open, the beginning of several weeks of a floral display from this species.  There are specialist bees that depend on the pollen of this species as the only food that their larvae can digest. In return, these bees are very efficient and reliable pollination partners for Spring Beauty.

Spring Beauty (Claytonia virginica)

Spring Beauty (Claytonia virginica), with Toadshade (Trillium sessile) behind it, in bud

So many other species are waiting in the wings to be the next to bloom, including Virginia Bluebells (Mertensia virginica).

Virginia Bluebells (Mertensia virginica)

Everything changes so quickly in spring, from one day to the next and from morning until afternoon.  Visit a natural area often so that you don’t miss anything.  And to give your immune system a boost.  You might even learn something!  Just avoid people.

The author, out for a walk in the woods.

Related Posts

Spicebush or Forsythia?

Bloodroot

Dutchman’s Breeches and Squirrel Corn

A Tale of Two Spring Beauties

Photo Locations

Bowman’s Hill Wildflower Preserve

Goat Hill Overlook, New Jersey

Rockhopper, New Jersey

Resources

All About Birds

National Wildlife Federation Educational Resources

US Forest Service Plant of the Week, Snow Trillium

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

Stearn, William T. Stearn’s Dictionary of Plant Names.  1996

 

 

Love Blueberries? Thank a Native Bee!

It’s blueberry season in New Jersey!  There are plenty of delicious deep blue orbs ripening for use on cereal, in pancakes, pies, crisps, cobblers, muffins, or just for snacking.  The blue color reflects the presence of anthocyanins, antioxidants with anti-inflammatory, anti-viral, and anti-cancer properties. Blueberries are not only tasty, but good for you.

A Bowl of Blueberries

For anyone who loves blueberries, you should know that some of our native bees are the most effective pollinators of this flavorsome fruit.

Blueberries are the fruit of deciduous shrubs that generally bloom in spring.  Most commercial blueberries in this region are cultivars of native blueberry species, usually Highbush Blueberry (Vaccinium corymbosum).  Lowbush Blueberry (Vaccinium angustifolium) is a species whose fruit is commonly harvested and sold in New England.  If the flowers are pollinated, the fruit ripens in mid to late summer, depending on their growing conditions.

Lowbush Blueberry (Vaccinium angustifolium)

An essential partner in the production of blueberries are the bees that are the primary pollinators for blueberry flowers.  While commercial growers may use Honey Bees to pollinate their crops, there are several species of native bees that are much more efficient blueberry pollinators.

How could that be?  Honey Bees pollinate flowers for a living.  Many are shipped from farm to farm specifically to pollinate crops.  (I think of them as the migrant workers of the insect world.)  How could there be bees that are more efficient pollinators?

Flowers come in all shapes and sizes, and they store and dispense their nectar (if they produce any) and pollen in many different ways.  Blueberry flowers are bell-shaped, with a narrow opening that allows access to the flowers’ nectar from the bottom of the hanging blossom.

Highbush Blueberry (Vaccinium corymbosum) Flowers

Lowbush Blueberry (Vaccinium angustifolium) Flowers

The pollen is most efficiently dispensed from the flowers’ anthers through a process called sonication, or ‘buzz’ pollination.  Buzz pollination is a process of releasing pollen by which the pollinator clings to the flower and vibrates its wing muscles without moving its wings.  This sets up enough of a vibration for the anthers to discharge a dusting of pollen on the flower visitor.  The wing vibration makes a buzzing sound, which gives this technique its name.  (Buzz pollination is the bee equivalent of ventriloquism!.)  Some of the pollen will be carried from flower to flower to enable pollination, while the rest is a pay-off for this service, and will be eaten by the bee and her larvae.  Bees drink nectar, but pollen is also a very important food source for them.

Honey Bees are not capable of buzz pollination, but several families of native bees are, including bumble bees, large carpenter bees, mining (Andrenid) bees, many sweat bees, some mason (Osmia) bees and Melitta bees.  Highbush and Lowbush Blueberry shrubs evolved with these bees who are native to the same region and habitats.  These native bees are able to handle the flowers more quickly and dispense and carry more pollen than the Honey Bees who lack this athletic skill.  Mason bees generally are very swift and efficient pollinators, able to process flowers many times more quickly than Honey Bees.

Mining Bee (Andrenid) visiting Lowbush Blueberry (Vaccinium angustifolium) Flower

Some of the native bees who are able to buzz pollinate specialize on visiting the flowers of blueberries; they and their larvae can only digest pollen from blueberry plants.  This is a great benefit to the blueberries, since these bees spend all of their foraging time visiting blueberry flowers, and there is no risk of pollen being dropped off on the wrong species.  It’s a risk for the bees, however.  If no blueberry flowers are available when the bees are active, the bees have no back-up plan; they could starve.  On the other hand, if blueberry flowers are available, it’s like assembly line processing. The bees know how to handle the flowers very efficiently to get the nectar and pollen they need to survive.

Mason Bee (Osmia) visiting Lowbush Blueberry (Vaccinium angustifolium) Flower

Blueberries are not the only crop that is most efficiently pollinated through sonication.  Cranberries, tomatoes, tomatillos, potatoes, peppers and eggplant are some of the other crops that have a higher rate of pollination when native bees with this skill are available to help pollinate their flowers.

A love of blueberries is not exclusive to people. Many other mammals and birds also enjoy the tasty fruit. Black bears are probably second to humans as consumers of blueberries, but fox, rabbits, raccoons, mice and many more eat their share, too.

Red Fox are among the animals that love blueberries.

Ruffed and Spruce Grouse relish the bounty blueberries provide,

Spruce Grouse

as do many other birds including Bluebirds, Catbirds, Scarlet Tanagers, Tufted Titmice, Veeries, Robins, and Brown Thrashers.

Eastern Bluebirds love blueberries

Veery in Fringtree (Chionanthus virginicus) Veeries are among the many birds who eat blueberries.

Butterflies and moths depend on blueberries, too, but in a completely different way.  Many species use the leaves and flowers as their caterpillar food.  The Natural History Museum’s Database of the World’s Lepidopteran Hostplants (HOSTS) lists 32 species that use Highbush Blueberry as caterpillar food, 42 that use Lowbush Blueberry.

Spring Azure butterfly. Highbush and Lowbush Blueberry shrubs are a caterpillar food plant for Spring Azures.

Saddleback moth caterpillar. Highbush and Lowbush Blueberry shrubs are a caterpillar food plant for Saddlebacks.

Caterpillars are an important part of the diet of many birds and other animals, so feeding caterpillars means that these other species will have the food they need, too.

Female Common Yellowthroat with Caterpillar

Blueberries are great landscape plants.  Not only do they provide food for our many animal neighbors (and us, if we’re quick!), but they are beautiful throughout the seasons, with their spring flowers, summer fruit, fabulous fall color and winter architectural structure and slightly shredding bark.  Why would anyone plant the non-native, invasive Burning Bush (Euonymus alatus) for its brief flash of color, when they could have blueberries instead?

Lowbush Blueberry (Vaccinium angustifolium) with Lichen in Fall

Highbush Blueberry is native primarily in the eastern third of the United States and Canada, but also in Washington state and British Columbia.  It is common in dry to wet woods, in thickets and on stream banks.  It can grow to a height of about 13 feet (4 meters).  Lowbush Blueberry is native from Manitoba to Newfoundland and Labrador provinces in Canada, and south as far as Tennessee and North Carolina (except Kentucky) in the United States. It can be found in dry woods and barrens, where its partnership with mycorrhizal fungi helps it to get the nutrients it needs from the soil.  It is a low growing plant, usually to a maximum height of about 2.5 feet (.75 meters).

The USDA NRCS Plant Database lists 25 species of blueberries that are native in different regions in North America.  Find one that’s native where you live, and add it to your landscape to enjoy its beauty and bounty.

A Bowl of Blueberries

A Bowl of Blueberries

Related Posts

Nutritious Fall Foliage – What Makes Leaves So Colorful?

The Buzz About Shooting Star

Partridge Pea Puzzles

Resources

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

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

Eastman, John.  The Book of Field and Roadside.  2003.

Holm, Heather.  Bees An Identification and Native Plant Forage Guide.  2017.

Mader, Eric; Shepherd, Matthew; Vaughan, Mace; Black, Scott Hoffman; LeBuhn, Gretchen.  Attracting Native Pollinators: Protecting North America’s Bees and Butterflies.  2011.

Martin, Alexander C.;  Zim, Herbert S.; Nelson, Arnold L.  American Wildlife & Plants A Guide to Wildlife Food Habits.  1951.

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

Tallamy, Douglas W.  Bringing Nature Home.  2007

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

Wilson, Joseph S.; Carril, Olivia Messinger.  The Bees in Your Backyard. 2016.

Illinois Wildflowers

Natural History Museum’s Database of the World’s Lepidopteran Hostplants – Vaccinium corymbosum

Natural History Museum’s Database of the World’s Lepidopteran Hostplants – Vaccinium angustifolium

 

Praying for Spring? So is Hobblebush Viburnum

Hobblebush Viburnum (Viburnum lantanoides) in winter

Praying for spring?  Based on appearances, it looks like Hobblebush Viburnum (Viburnum lantanoides, synonym V. alnifolia) is doing the same thing.

Many woody plants can be identified in winter by their distinctive leaf and flower buds, including Hobblebush.  Its leaf ‘buds’ are miniature immature leaves that survive the winter without protective scales.  Since Viburnums have leaves opposite each other along their branches and at branch tips, these leaf ‘buds’ are paired together, a perfect mimic of hands held in prayer.

Hobblebush Viburnum (Viburnum lantanoides) ‘naked’ leaf buds, a term that refers to buds without protective scales.

Where flower buds are present, they nestle between the two leaves in a pair.  In this configuration, the flower buds resemble a moose head, with the leaf ‘buds’ playing the role of moose ears.  That could explain why another common name for this shrub is Moosewood!

Hobblebush Viburnum (Viburnum lantanoides) leaf and flower buds. Do you see the resemblance to a female moose head?

Before the canopy trees have finished leafing out in spring, Hobblebush leaves begin to expand and grow, maximizing their ability to photosynthesize.  At the same time, the flowers also begin to bloom.

Hobblebush Viburnum (Viburnum lantanoides) in spring

Like some hydrangeas, Hobblebush inflorescences have two types of flowers, large sterile flowers around the perimeter of the flower cluster that are incapable of producing fruit, and masses of small fertile flowers in the center.  The sterile flowers open first.

Hobblebush Viburnum (Viburnum lantanoides), with leaves unfurling and sterile flowers blooming. The fertile flowers in the center of the inflorescence are still in bud.

The fertile flowers are where the serious work of pollination takes place.  They open a few at a time over several days, giving the plant a long period during which to lure visitors to help pollinate its flowers. At the same time it’s providing food to those pollinators over many days.  It’s a win-win.

Hobblebush Viburnum (Viburnum lantanoides), with fertile flowers beginning to bloom.

Why would a plant have sterile flowers?  Studies show that there is a higher rate of successful pollination in Hobblebush’s fertile flowers when these showy sterile flowers are present.  The sterile flowers help to advertise the plant’s offerings, luring pollinators to the inflorescence.  The many small fertile flowers make efficient use of the remaining space, offering more chances for the plant to reproduce than would be the case if all of the flowers were as large as those in the outer circle.  Aster family members have evolved a similar strategy.  Many have flower heads with a perimeter of showy but sterile ray flowers surrounding a dense cluster of tiny, tubular, fertile disk flowers.

Hobblebush Viburnum (Viburnum lantanoides) in bloom, with flies foraging on the flowers.

A relatively flat flower cluster like those of Hobblebush Viburnum can accommodate lots of different pollinators, including many bee and fly species.  As an insect moves from flower to flower foraging for food, its body brushes against and picks up pollen from the anthers at the tips of the stamens beneath it. This is an especially effective method of transporting pollen with insects that have hairy bodies to which the pollen can easily adhere.  On the day I observed Hobblebush flowers, flies were the most common visitors.  Flies are important pollinators, especially when the weather is cool; many species are able to fly at lower temperatures than bees.

Hobblebush Viburnum (Viburnum lantanoides) in bloom, with Syrphid fly

If you look closely, you can see that the flies are actually eating the pollen. Many bees and flies harvest both nectar and pollen when they visit flowers.  In addition to eating pollen themselves, female bees gather it to feed their larvae.

Hobblebush Viburnum (Viburnum lantanoides) with Syrphid fly eating pollen. The coloration of this fly mimics a wasp or bee, a disguise to deter predators, but its short antennae identify it as a fly to a discerning eye.

Some butterflies and moths use Hobblebush for food in a different way.  The caterpillars of Spring Azure butterflies and Hummingbird Clearwing moths both eat the leaves or buds of this shrub.

Spring Azure butterfly. Its caterpillars eat the flower buds and leaves of several shrub species, including Hobblebush.

While Hummingbird Clearwing Moths drink nectar from the flowers of many different plants, their caterpillars most frequently eat Viburnum leaves. This mature moth is visiting Swamp Milkweed (Asclepias incarnata) for a quick beverage.

In autumn, Hobblebush leaves turn stunning shades of pink, red and maroon.

Hobblebush Viburnum (Viburnum lantanoides) in fall.

Stunning fall foliage of Hobblebush Viburnum (Viburnum lantanoides)

At the same time the leaves are changing color, the fruit that results from pollinated flowers ripens from green to red, then deepens to a dark blue-black.

Hobblebush Viburnum (Viburnum lantanoides) with ripening fruit

The fruit is a drupe, a fleshy fruit with its seed encased inside in a hard coating.  A peach is an example of a drupe.  Hobblebush fruit is edible for humans, although you may want to avoid those seeds.  Many birds and mammals also eat the fruit, and subsequently ‘disperse’ the seeds, complete with fertilizer.  A few of the animals that eat Hobblebush fruit are pictured below.

American Robin

Northern Cardinal

Hermit Thrush

Eastern Chipmunk

Red Squirrel

In addition to reproducing through its flowers and fruit, Hobblebush can reproduce vegetatively.  Where its branches come in contact with the ground, roots can form and a new shoot can sprout.

Hobblebush Viburnum (Viburnum lantanoides)

Hobblebush Viburnum is a deciduous shrub that can be found in moist woods in Ontario, Quebec, Newfoundland and New Brunswick in Canada, and in the northeastern United States from Maine to northeastern Ohio, south to northern New Jersey and Pennsylvania, and in the Appalachian Mountain region as far south as northeastern Georgia.

Hobblebush is fervent in its belief that spring will eventually arrive.  We should be, too!

Hobblebush Viburnum (Viburnum lantanoides) praying for spring

Related Posts

Asters Yield a Treasure Trove

Nutritious Fall Foliage: What makes leaves so colorful?

Resources

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

Martin, Alexander C.;  Zim, Herbert S.; Nelson, Arnold L.  American Wildlife & Plants A Guide to Wildlife Food Habits.  1951.

Peterson, Lee Allen.  A Field Guide to Edible Wild Plants of Eastern and Central North America. 1977.

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

Spira, Timothy A.  Wildflowers & Plant Communities of the Southern Appalachian Mountains & Piedmont.  2011.

Tallamy, Douglas W.  Bringing Nature Home.  2007

Thompson, Elizabeth H.; Sorenson, Eric R.  Wetland, Woodland, Wildland A Guide to the Natural Communities of Vermont.  2005.

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

Adirondacks Forever Wild:  Shrubs of the Adirondacks

Annals of Botany.  Sterile marginal flowers increase visitation and fruit set in the hobblebush (Viburnum lantanoides, Adoxaceae) at multiple spatial scales.

Biology Discussion

USDA NRCS Plants Database

 

 

Oaks Have a Lot of Gall!

In late fall and early winter, oak (Quercus species) trees often stand out from their forest companions, refusing to let go of their richly colored russet and brown leaves long after other deciduous trees are completely bare.  Oaks are members of the Beech (Fagaceae) family, and winter leaf retention, or marcescence, is a family trait.  American Beech (Fagus grandifolia) trees tenaciously hold their leaves until early spring when new leaves are preparing to emerge.

Oak trees, retaining their leaves, stand out in a woodland in late fall.

No one knows exactly why some deciduous trees exhibit this characteristic, but there are several theories.  It may be that the dry leaves are a deterrent to winter browsing by deer, moose and other mammals.  Holding on to leaves until spring may be the trees’ way of time-releasing nutrients for recycling into the soil.  Or the leaves may capture and funnel more snow melt to the tree’s root system.

There are about 600 species of oaks (Quercus) worldwide, with 87 in North America, as well as numerous hybrids.  Oaks are usually categorized in two groups, the white oak group and the red oak group.  They can be distinguished by their leaves.  Trees in the white oak group have leaves with rounded lobes,

White Oak (Quercus alba)

while trees in the red oak group have leaves with pointed lobes or with very narrow ‘pins’ at the tips of their lobes.

Red Oak (Quercus rubra)

Oaks are among the most valuable species for supporting both wildlife and people, in many different ways.

The wind-pollinated flowers of oaks produce acorns, an important food for wildlife.

Acorn of Swamp White Oak (Quercus bicolor)

Many birds depend on this bounty of food, including Jays, Tufted Titmice, Red-headed and Red-bellied Woodpeckers, Ruffed Grouse, Lesser Prairie Chickens, Bobwhite and other quails, and Wild Turkeys.

Red-bellied Woodpeckers are among the many birds that eat acorns.

White-breasted Nuthatches are most often seen foraging for food, mostly insects, in the crevices of tree bark, but they also like fruit, and are named for their habit of tucking seeds and nuts like acorns into a crevice and hacking away at them to consume the tasty treat inside.  They may also cache some acorns for later consumption.

White-Breasted Nuthatch

Even Wood Ducks consume acorns.  They primarily live in forested wetlands where oak trees and acorns may be present. Wood Ducks are just one of the many animals that nest in tree cavities such as those found in oaks.

Wood Duck in fall

Acorns are an important food source for many mammals, from mice, chipmunks, raccoons and squirrels, to bear and deer.

Raccoons are among the many mammals that eat acorns, and may find shelter in oak or other tree cavities.

Eastern Gray Squirrels have a special relationship with oaks.  Not only do they consume acorns and shelter in oak cavities, but in return they help to disperse oak seeds (acorns).  Like the White-breasted Nuthatches, Gray Squirrels cache acorns for later consumption.  Squirrels typically have a very good memory for where they stashed each acorn, often recovering as much as 95% of their hoard.  But the other overlooked 5% may germinate and prosper in their new location.  Oaks also tend to have ‘mast years’ when they produce more acorns than can be easily eaten even over the long winter.  In such years, many acorns may live to become trees.

Eastern Gray Squirrel

Acorns are at their most nutritious before they germinate.  Acorns of trees in the white oak group germinate in their first year.  Squirrels can detect this, and are likely to eat acorns from the white oak group as soon as they are available rather than cache them.  Trees in the red oak group produce acorns that take two years to germinate.  Squirrels are likely to cache acorns from trees in the red oak group, since they remain a viable food source for a longer period of time.

When acorns are plentiful, Gray Squirrels, Blue Jays, White-footed Mice and other acorn consumers tend to eat only about half of each acorn, the half at the opposite end from which the tree seedling will emerge (the end without the ‘cap’).  This part of the acorn has a higher lipid content, the food these animals are seeking, and a lower tannin content, a bitter tasting compound that is off-putting to potential consumers.  The discarded uneaten half acorn will often germinate and produce a seedling.

Studies have shown that in the mid-Atlantic United States, oaks are food plants for the caterpillars of more butterfly and moth species than any other genus of trees, supporting more than 500 species.

Juvenal’s Duskywing nectaring from Spring Beauty (Claytonia virginica). Several Duskywing butterfly species use oaks as caterpillar food.

Red-banded Hairstreaks use the fallen leaves of oaks and sumacs as caterpillar food. The spend the winter in the fallen leaves.

Saddleback moth caterpillars eat oak leaves

Several giant silk moths like this Polyphemus Moth and Luna Moths depend on oaks for caterpillar food.

Insects, and especially caterpillars, are an important source of food for birds and other animals.  It takes thousands of caterpillars to feed a young bird family.  As a result, many of those caterpillars will become a meal before they get a chance to become a butterfly or moth.

Carolina Chickadees need thousands of caterpillars to raise a single brood.

Carolina Wrens need food in the form of the many caterpillars and other insects found on oak trees.

There are other insects whose presence in oak tissue stimulates the oak to produce a gall, an abnormal plant growth with more nutrients than are found in normal tissue.  The insect develops inside the gall, feeding on the nutrient rich tissue inside.  Some oak galls are caused by midges, but many are caused by members of a sub-family of wasps called gall (Cynipid) wasps.  The galls take some of the plant’s resources, but they typically don’t cause any harm to the plant.  Often these galls house additional insects, free-loaders (inquilines) that didn’t stimulate the tree to produce the gall but who live and feed in the gall, sharing it with the original tenant.

The galls on these Pin Oak (Quercus palustris) leaves are caused by a midge, Polystepha pilulae.

This gall on Swamp White Oak (Quercus bicolor) is called a Lobed or Pine Cone Oak Gall. It is caused by a wasp.

This summer my attention was drawn to a Swamp White Oak (Quercus bicolor)  branch by ants rapidly climbing around on several ‘bumps’ that could only be galls.  At this point the galls were somewhat nondescript little growths that turned out to be Oak Bullet Galls.

Ants patrolling galls on Swamp White Oak (Quercus bicolor)

But what attracted the ants to the galls?  Ants are omnivorous. Other insects are important food for them, but they also eat plant material and sweet tasty treats, like nectar.  Since they didn’t have access to the insects inside the galls, I speculated that there was something on the exterior of the gall that enticed them.  When I looked at my photos, they did appear to be eating something, but what?

Ants with Oak Bullet Galls galls on Swamp White Oak (Quercus bicolor)

When I checked on the galls about a week later, their appearance had changed dramatically; they now looked like red Hershey’s Kisses.  The ants were still on duty, and this time when I checked my photos, I could see droplets of nectar oozing out from the sides of the galls.  Mystery solved!  The wasp inside the gall had stimulated the tree to not only produce its home and food, but the home came equipped with a security system – nectaries to lure and pay for protection from predators.

Ant drinking nectar from Oak Bullet Gall on Swamp White Oak (Quercus bicolor). The glistening nectar droplets are especially visible just below the tip of the ant’s right front leg.

My next visit was about two weeks after the Hershey’s Kisses phase of the gall development.  Their appearance had changed again; now each gall had a tan, almost perfectly round exterior.  This time the ants were joined on patrol by several wasp species, each capable of discouraging predators of the gall wasp.

Paper Wasp drinking nectar from Oak Bullet Gall on Swamp White Oak (Quercus bicolor).

Cuckoo Wasp drinking nectar from Oak Bullet Gall on Swamp White Oak (Quercus bicolor).

This seems like an expensive security service for the tree to provide if it only benefits the gall wasp.  It is likely that many of these insect guards also protect the tree itself from other herbivores.  For example, Paper Wasps, like ants, are caterpillar predators.

Oaks also have relationships with many fungi, including species that are edible or provide medicine for humans, insects and other animals.

Hen of the Wood is just one of the many fungi that have a relationship with oak trees.

There is a plant called Squawroot or Cancer-root (Conopholis americana) that depends on oaks for its survival.  Squawroot doesn’t produce its own food through photosynthesis. Instead it taps into the roots of oak trees for its food.

Squawroot or Cancer-root (Conopholis americana)

How are oak trees beneficial for people?   If prepared correctly, some acorns are edible.  The wood is used for building, furniture and cabinet making.  The bark of some species is used for tanning.  Oak trees, especially the inner bark, have numerous medicinal uses.  Most importantly, through photosynthesis, oak trees and other plants produce the oxygen we need in order to breathe.  They help mitigate climate change by removing carbon dioxide and other pollutants from our air and water, providing cooling shade, producing moisture through transpiration, and helping to manage stormwater.

Swamp White Oak (Quercus bicolor)

Not only do oaks have a lot of gall, but they provide immeasurable value to life on earth.

Oak trees stand out in a woodland in late fall

Related Posts

Will Work for Food – Extra-floral Nectaries

American Beech

Resources

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

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

Eastman, John.  Birds of Forest, Yard, & Thicket.  1997.

Eastman, John.  Birds of Lake, Pond and Marsh.  1999.

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

Eastman, John.  The Book of Swamp and Bog.  1995.

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

Eiseman, Charley; Charney, Noah.  Tracks & Sign of Insects and Other Invertebrates.  2010.

Martin, Alexander C.;  Zim, Herbert S.; Nelson, Arnold L.  American Wildlife & Plants A Guide to Wildlife Food Habits.  1951.

Nelson, Gil; Earle, Christopher J.; Spellenberg, Richard.  Trees of Eastern North America.  2014.

Sibley, David Allen.  The Sibley Guide to Bird Life and Behavior.  2001.

Steele, Michael A.; Koprowski, John L.  North American Tree Squirrels.  2001.

Tallamy, Douglas W.  Bringing Nature Home.  2007

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

Buckeye Yard and Garden Online: Bullet Galls and Their Guards by Joe Boggs, October 2018

Capital Naturalist by Alonso Abugattas

Illinois Wildflowers

Minnesotaseasons.com

Missouri Botanical Garden

Naturalis Historia

Penn State College of Agricultural Sciences, Winter Leaves That Hang On

 

 

Crayon-colored Hickories

Mockernut Hickory (Carya tomentosa)

The compound leaves of Hickory (Carya species) trees still clinging to their branches are displaying colors that remind me of crayons:  yellow-green, yellow-orange, lemon-yellow, chestnut, burnt umber.  Together with the reds and browns of Oaks, the tans and peach of American Beech, they are part of the mid-fall forest pallette.   Shagbark (Carya ovata), Mockernut (C. tomentosa) and Bitternut (C. cordiformis) are the Hickories I encounter most often.

Mockernut Hickory (Carya tomentosa).

Mockernut Hickory (Carya tomentosa).

Those Hickory leaves may have supported up to 200 different species of butterflies and moths as food for their caterpillars, all without any negative impact on the appearance of the trees. Some of the species Hickories support are Banded and Hickory Hairstreak butterflies, and many moths, including Hickory Tussock, Yellow-shouldered Slug, and the dramatic Hickory Horned Devil, the largest of our native North American caterpillars.

Banded Hairstreak on Indian Hemp (Apocynum cannabinum). Banded Hairstreak caterpillars eat Hickory leaves, as well as some other woody species.

Banded Hairstreak on Indian Hemp (Apocynum cannabinum). Banded Hairstreak caterpillars eat Hickory leaves, as well as some other woody species.

Hickory Tussock Moth Caterpillar

Hickory Tussock Moth Caterpillar

Yellow-shouldered Slug

Yellow-shouldered Slug

The aptly named, acrobatic Hickory Horned Devil caterpillar.

The aptly named, athletic, Hickory Horned Devil caterpillar.

All of those caterpillars are fair game for birds, looking for food for themselves and their growing offspring. Insects, especially caterpilIars, are an important source of food for birds.  It can take thousands of caterpillars to raise a hungry clutch of baby birds.

Wood Thrush at the nest with babies

Wood Thrush at the nest with babies

Some caterpillars may fall victim to other predators, like spiders, predatory wasps or flies, and assassin bugs.

Brown Assassin Bug (Acholla multispinosa) on Bitternut Hickory bud.

Brown Assassin Bug (Acholla multispinosa) on Bitternut Hickory bud.

Hickory nuts also supply food for animals, including people. The husks have four sections that split open to reveal the hard shell protecting the nut ‘meat’ inside.

Shagbark Hickory (Carya ovata) nuts

Shagbark Hickory (Carya ovata) nuts

Mockernut Hickory (Carya tomentosa) nuts split partially open, like this one.

Mockernut Hickory (Carya tomentosa) nuts split partially open, like this one.

Hickory nut on the right, empty husk pieces on the left

Hickory nut on the right, empty husk pieces on the left

Eastern Chipmunks, Red, Gray, Fox and Flying Squirrels, Raccoons, and rabbits all eat Hickory nuts. Squirrels may bury some of the nuts rather than eating them right away.  This habit helps to disperse the Hickories if the squirrels don’t come back and eat the nuts at a later date.

Eastern Chipmunk (with full cheeks!)

Eastern Chipmunk (with full cheeks!)

Gray Squirrel

Gray Squirrel

Fox may also eat Hickory nuts, or they may eat the smaller animals who eat the nuts.

Red Fox eating Gray Squirrel

Red Fox eating Gray Squirrel

Wild Turkeys, Bobwhites, Red-bellied Woodpeckers, Blue Jays, Rose-breasted Grosbeaks and even Wood Ducks are among the birds that consume the tastier species of Hickory nuts.

Red-bellied Woodpecker

Red-bellied Woodpecker

Male Wood Duck in non-breeding plumage

Male Wood Duck in non-breeding plumage

Hickory trees provide food and building material for humans, too.   Shagbark is the species whose nuts are most often sold commercially.  As you might guess from its name, Bitternut Hickory is not sought after for its nuts.  Pecans (Carya illinoinensis) are in this same genus and are an important commercial crop.  Hickory sap can be used to make syrup or other sweeteners.

Shagbark is also the species whose wood is most often used commercially for making handles, ladder rungs, wheel spokes, flooring, and a hickory-smoked flavor for cooking. Named for its shaggy strips of bark, Shagbark Hickory stands out from the crowd.

Can you pick the Shagbark Hickory (Carya ovata) out of the crowd?

Can you pick the Shagbark Hickory (Carya ovata) out of the crowd?

The bark offers warm, dry accommodations for insects and others trying survive the winter.

Spider web on Shagbark Hickory (Carya ovata)

Spider web on Shagbark Hickory (Carya ovata)

Eastern Comma butterflies survive the winter as adults, if they can find a warm dry shelter like a space under the loose bark of Shagbark Hickory (Carya ovata).

Eastern Comma butterflies survive the winter as adults, if they can find a warm dry shelter like a space under the loose bark of Shagbark Hickory (Carya ovata).

Mockernut Hickory also has distinctive bark, but in a completely different way. Its gray, smooth-looking, corky exterior forms sinuous ridges along the length of the trunk.

Mockernut Hickory (Carya tomentosa). Notice the curved ridges in the bark, especially in places where branches have fallen off.

Look for Hickory trees even after their leaves fall. You may be able to identify them by their bark and their buds.  Hickories typically have a single large end bud at the tip of their branches that is usually quite distinctive, different for each species.  There are smaller buds spaced alternately along the length of the branches.

Mockernut Hickory buds are somewhat rounded, echoing the curved pattern of the bark ridges.

Mockernut Hickory (Carya tomentosa) branch in winter. Notice the large end bud with rounded sides.

Mockernut Hickory (Carya tomentosa) branch in winter. Notice the large end bud with rounded sides.

Shagbark Hickory usually retains contrasting bud scales, which you might think of as being reminiscent of the shaggy bark.

Shagbark Hickory (Carya ovata) bud. Notice the bod scales hugging the sides.

Shagbark Hickory (Carya ovata) bud. Notice the scales hugging the sides of the bud.

Bitternut Hickory buds are a bright mustard color that is difficult to mistake for anything else.

Bitternut Hickory (Carya cordiformis), showing its distinctive mustard-colored buds.

Bitternut Hickory (Carya cordiformis), showing its distinctive mustard-colored buds.

As winter turns to spring, watch for these buds to swell and unfold like flowers.

Mockernut Hickory (Carya tomentosa) leaves unfolding in spring.

Mockernut Hickory (Carya tomentosa) leaves unfolding in spring.

Shagbark Hickory (Carya ovata) in spring

Shagbark Hickory (Carya ovata) in spring

The range for Shagbark and Bitternut Hickory includes much of the eastern two-thirds of the United States, and Ontario and Quebec provinces in Canada. Mockernut’s range is similar, but it does not include the Canadian provinces, or some of the northern tier of the United States.

Enjoy the colorful foliage while it lasts!

Mockernut Hickory (Carya tomentosa)

Mockernut Hickory (Carya tomentosa)

Related Posts

Nutritious Fall Foliage: What Makes Leaves So Colorful

American Beech

In Praise of Black Walnut Trees

Resources

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

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

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

Martin, Alexander C.; Zim, Herbert S.; Nelson, Arnold L. American Wildlife & Plants A Guide to Wildlife Food Habits.  1951.

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

Stearn, William T. Stearn’s Dictionary of Plant Names.  1996

Tallamy, Douglas W. Bringing Nature Home.  2007

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

Illinois Wildflowers
http://www.illinoiswildflowers.info/trees/plants/btnt_hickory.html
http://www.illinoiswildflowers.info/trees/plants/mock_hickory.html

Tallamy, Douglas W. Bringing Nature Home

USDA NRCS Plant Database
https://plants.usda.gov/core/profile?symbol=CAOV2
https://plants.usda.gov/core/profile?symbol=caco15
https://plants.usda.gov/core/profile?symbol=CAAL27

The Wood Database