Southern Red Oak – Quercus falcata : Fall Leaf Patterns

Quercus falcata, the Southern Red Oak, is one of the commonest upland oak species in the Central Piedmont of North Carolina.  It is a member of the red oak group, which is characterized primarily by the bristles at the end of the leaf lobes, and by acorns that require two years to mature.  The Southern Red Oak has a prodigious array of leaf patterns, a characteristic that is difficult to appreciate in the spring and summer when the leaves are high on the tree, but is conspicuous when the leaves are directly  under foot in the late fall and winter.

The species name falcata is descriptive of the majority of mature leaves, falcate meaning curving and tapering gradually to a point.  The fall leaves pictured below are easily recognized, and are most commonly associated with the Southern Red Oak.  They are shown with the reverse side up to illustrate the tawny, light color of the underside, which remains fuzzy to the touch even after the leaf dies and is shed.

Quercus falcata Southern Red Oak Falcate Leaves

Quercus falcata
Southern Red Oak
Falcate Leaves

Quercus falcata Southern Red Oak Falcate Leaves

Quercus falcata
Southern Red Oak
Falcate Leaves

This oak has quite a repertoire of intermediate shapes and sizes that are not always immediately recognizable as Southern Red Oak.  A few of them are shown below, but there are many more than this photo illustrates.  These leaves are shown topside up.

Quercus falcata Southern Red Oak Intermediate Leaf Shapes

Quercus falcata
Southern Red Oak
Intermediate Leaf Shapes

Small, immature trees have very different leaf patterns, most of which could be described as tri-lobed, with the tips of the leaves having a rounded, blunt appearance.   Completely ovate leaves can also be found, a shape not well known or described.  The leaves below came from a young, 15 foot Southern Red Oak , and  all the leaves were taken from the same branch.

Quercus falcata Southern Red Oak Leaves of an Immature Tree

Quercus falcata
Southern Red Oak
Leaves of an Immature Tree

The leaf shapes illustrated above are  not restricted to saplings, but can sometimes be seen on trees of medium height.  The ovate leaves on the lower right in the photo still have the characteristic bristles, approximately where the three lobes would be if they were present.  See below.

Quercus falcata Southern Red Oak Ovate Leaf with Bristles

Quercus falcata
Southern Red Oak
Ovate Leaf with Bristles

Blackjack Oaks, Quercus marilandica, are much less common than Southern Red Oaks, but do appear sporadically in the same areas.  Their leaf shapes are much less diverse, but can sometimes be confused with the immature Southern Red Oaks.  A few representative Blackjack Oak leaves are pictured below.

Quercus marilandica Blackjack Oak Typical Fall Leaves

Quercus marilandica
Blackjack Oak
Typical Fall Leaves

Three tri-lobed leaves from a young Southern Red Oak are at the top of the next picture, with two Blackjack Oak leaves below them.  These leaves were taken from young trees directly adjacent to each other, with some of the branches intertwined.  It is easy to see how they could be confused.

Leaves of Southern Red Oak at the Top, with Blackjack Oak Leaves Below

Leaves of Southern Red Oak at the Top, with Blackjack Oak Leaves Below

While the leaves of the Blackjack Oak pictured above are coarsely lobed, they are usually shallower than the lobes of the Southern Red Oak above.  In addition, the tips of the Blackjack Oak leaves are wider proportionally than the Southern Red Oaks.

The Pagoda or Cherrybark Oak (Quercus pagoda) has  probably the most difficult leaf to distinguish from the Southern Red Oak.  In fact, at one time the Pagoda Oak was classified as a variety of the Southern Red Oak.  Below are typical leaves of the Pagoda Oak.

Quercus pagoda Pagoda Oak Typical Leaves

Quercus pagoda
Pagoda Oak
Typical Leaves

Below is a comparison between two Southern Red Oak leaves (on the left) and two Pagoda Oak leaves (on the right).

Southern Red Oak Leaves on the Left vs. Pagoda Oak Leaves on the Right

Southern Red Oak Leaves on the Left vs. Pagoda Oak Leaves on the Right

The base of the Southern Red Oak leaves tend to be rounded while the base of the Pagoda Oak leaves tend to be sharp and angular.  The Pagoda Oak leaves also  tend to be more symmetrical, with lobes often opposite each other, while regular symmetry is not common in Southern Red Oak leaves.  When distinguishing these two trees, it helps to look at many leaves rather than just a few as pictured above.

Leaf shape depends on many variables and is seldom used alone to distinguish tree species.   Location on the tree (sun vs. shade), soil type and habitat, rainfall or lack of it, and most importantly genetics, all affect leaf shape.

Herb Amyx

 

 

 

 

 

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Kudzu Swallows a Local Greenway

The word “neglect” always carries a negative connotation.  It is worse than just ignoring, for neglect takes place over a period of time and usually leads to harmful consequences.  Neglect is perhaps the most important feature of Kudzu invasions.  Kudzu thrives on neglect.

Kudzu (Pueraria montana var. lobata) is perhaps the best known invasive plant in the South.  A member of the bean family (Fabaceae),  and a native of Asia, it is a rapidly growing, twining vine with large, floppy leaves composed of three leaflets.  Its prodigious summer growth rate (up to a foot a day) is legendary.

The greenway pictured below is located near Falls Lake and the town of Wake Forest, North Carolina.  It was built by a commercial developer who began a project on a large parcel of land, with the greenway circumscribing one edge of the property.  The project fell through, and the parcel was abandoned, leaving no one responsible for the greenway.

Faced with no opposition, Kudzu and other weeds began to overtake the greenway.  These photos were taken in September, 2013.  Below, Kudzu is flowing down a section of the asphalt trail like green lava.

Kudzu Covering Abandoned Greenway

Kudzu Covering Abandoned Greenway

Next, Kudzu shrouds a slope, with a pedestrian underpass partially hidden but still visible in the center.

Kudzu Covering the Slopes and Sides of an Abandoned Greenway

Kudzu Covering the Slopes and Sides of an Abandoned Greenway

Hanging vines of Kudzu, Japanese Honeysuckle, and English Ivy begin to form a hanging garden down the brick greenway wall.

Hanging Vines on Greenway Wall

Hanging Vines on Greenway Wall

An upper portion of the trail has large numbers of Dogfennel (Eupatorium capillifolium) and other weeds growing on the sides while trailing vines of Kudzu can be seen making their way up the edge of the path.

Dogfennel and Kudzu Along a Portion of the Greenway

Dogfennel and Kudzu Along a Portion of the Greenway

In photos taken this November, 2015, some changes are evident.  Kudzu vines have grown all the way to the top of many trees bordering the greenway.  The asphalt trail is mostly covered with a thatch of Kudzu vines which have resisted the traffic from mountain bikes, runners and walkers.

Asphalt Trail Covered by Kudzu Vines

Asphalt Trail Covered by Kudzu Vines

Growth of the brambles, young pines, and woody plants bordering the trail has created a corridor of plants covered by kudzu vines up to six feet tall.  Only mountain bikes and foot traffic have kept the corridor from closing off the path.

Narrow Corridor Formed on Path From Growing Plants and Kudzu

Narrow Corridor Formed on Path From Growing Plants and Kudzu

The hanging gardens have proliferated and now close off most of the brick wall.

Hanging Vines Have Covered Most of the Greenway Wall

Hanging Vines Have Covered Most of the Greenway Wall

This abandoned greenway will eventually  serve as a connector to join together a larger greenway system.  When the time comes to clear the mass of plants, the Kudzu showing above the ground will be a big task.  But the more difficult problem will be the large, central root crowns which have had time to gain size and strength, and to anchor deep roots.  In cases like this, it takes time and persistence, sometimes several seasons, to remove or kill the crowns.

Herb Amyx

 

 

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North Carolina’s Rare Serpentine Aster – Symphyotrichum depauperatum

Symphyotrichum depauperatum, the Serpentine Aster, may be the most unusual native aster in North Carolina.  It is extremely rare, with a state ranking of  Critically Imperiled, and a status of Endangered .    In addition, it is found at only a single site (Granville County) in North Carolina.  Also remarkable and unique is its occurrence on a diabase glade in North Carolina.  All other populations in North America are found on serpentine barrens, primarily in Maryland and Pennsylvania.  Its occurrence on serpentine soils (more about this later) gave rise to the common name of Serpentine Aster.

Symphyotrichum depauperatum is a diminutive, fragile aster with thin stems, and small flowers.  The flowers have 7 to 14 white rays and yellow discs.  The leaves on the flowering stems are tiny, narrow and sharply pointed.  See below.

Symphyotrichum depauperatum Serpentine Aster

Symphyotrichum depauperatum
Serpentine Aster

The plant above is shown below with a hand in the photo to demonstrate its small size.

Symphyotrichum depauperatum Serpentine Aster

Symphyotrichum depauperatum
Serpentine Aster

Below is another fully developed aster against the backdrop of a camera case.  The photo shows a typical blooming form of the Serpentine Aster.  The camera case is 8 inches tall.

Symphyotrichum depauperatum Serpentine Aster

Symphyotrichum depauperatum
Serpentine Aster

The basal leaves in this group of asters were quite variable, but tended to be rounded in the newer leaves, and lanceolate to spatulate in the more developed leaves.  The first photo below shows the basal leaves just emerging and the second photo shows an older aster whose basal leaves are mature.  Also note the ciliate (fine hair) leaf margins  in the two photos below.

Syphyotrichum depauperatum Serpentine Aster Basal Leaves

Symphyotrichum depauperatum
Serpentine Aster
Basal Leaves

Symphyotrichum depauperatum Serpentine Aster Basal Leaves

Symphyotrichum depauperatum
Serpentine Aster
Basal Leaves

As with many perennial asters, the basal leaves wither when the aster begins to bloom, but new basal leaves develop to take their place.  Red arrows in the photo below show the basal leaves that have just withered, underneath the newly arrived leaves.  The ciliate leaf margins are still visible on some.

Symphyotrichum depauperatum Serpentine Aster Withered Basal Leaves

Symphyotrichum depauperatum
Serpentine Aster
Withered Basal Leaves

As mentioned above, the occurrence  of the Serpentine Aster in a diabase glade is very unusual.  Serpentine barrens are harsh and demanding ecosystems that arise on serpentine soils derived from underlying serpentonite rock.   In the U.S., most occur in Maryland, Pennsylvania, and California.  They are characterized by shallow soils with a low nutrient content, low water holding capacity, high magnesium and low calcium (an unfavorable ratio for plants), and high levels of metals like chromium and nickel.   Thus it is no surprise that the species name for the Serpentine Aster, depauperatum, is derived from the Latin for impoverished or starved.

While diabase soils can also be shallow and have a high Magnesium content, they generally have an adequate nutrient content and sufficient calcium for a favorable magnesium/calcium ratio.  The Serpentine Aster’s presence at this site in North Carolina remains somewhat of a mystery.

Herb Amyx

For more on serpentine habitats see:

Intraspecific Variability in the Response of Certain Native Plant Species to Serpentine Soil.  Arthur R. Kruckeberg, American Journal of Botany, Vol 38, No 6 (June, 1951) pp 408-419

Brian Anacker. 2014. The nature of serpentine endemism. American Journal of Botany. 101: 219-224.

 

 

 

 

 

 

 

 

 

 

 

 

 

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Fall Wildflowers on the Road to Rockcliff Farm

Rockcliff Farm is located over a mile and a half from the entrance to the B.W. Wells State Recreation Area at Falls Lake, North Carolina.  Much of the area along the road to the farm is heavily wooded, but large open areas, especially adjacent to power lines, can also be found.   It is in the open areas, where sun penetrates for part of the day, that wildflowers adapted to roadside habitats thrive.

One of the most common roadside wildflowers in North Carolina is the Maryland Golden Aster (Chrysopsis mariana), and many can be found along this road.  While most wild asters are white or blue, this aster has large, yellow flowers that immediately catch the eye.  As seen below, many plants have multiple stems, forming natural flower clusters.

Chrysopsis mariana Maryland Golden Aster

Chrysopsis mariana
Maryland Golden Aster

Chrysopsis mariana Maryland Golden Aster

Chrysopsis mariana
Maryland Golden Aster

Much less common in the Falls Lake area is the Eastern Silvery Aster (Symphyotrichum concolor), a small native aster with blue flowers.  Asters are identified more by their foliage than their flowers, which are often similar to each other.  The Eastern Silvery Aster is easy to identify due to its unique and unusual leaves.  Small and flat, with a silvery sheen, the leaves press tightly upward against the stems.   Seen below is an aster lying flat on the ground due to heavy rains.

Symphyotrichum concolor Eastern Silvery Aster

Symphyotrichum concolor
Eastern Silvery Aster

A closer look at the unique leaves and the flowers.

Symphyotrichum concolor Eastern Silvery Aster

Symphyotrichum concolor
Eastern Silvery Aster

Symphyotrichum concolor Eastern Silvery Aster Leaves

Symphyotrichum concolor
Eastern Silvery Aster
Leaves

Symphyotrichum concolor Eastern Silvery Aster Flowers

Symphyotrichum concolor
Eastern Silvery Aster
Flowers

The Purpledisk Sunflower (Helianthus atrorubens) is another common roadside wildflower.  It is tough, hardy, and extremely drought resistant.  The flowering stems often reach 4 to 6 feet high from a large basal rosette of fuzzy leaves.  But the Purpledisk Sunflowers on this road are blooming only 8 to 10 inches above the ground from very small basal leaves.  This is a result of frequent mowing on this section of the road, which continually cuts the stems back.   But the flower, as seen below, is normal in size.

Helianthus atrorubens Purpledisk Sunflower Flower

Helianthus atrorubens
Purpledisk Sunflower
Flower

This year, a few Downy Lobelias (Lobelia puberula) have appeared in the powerlines adjacent to the road.  A late-blooming perennial covered with fine hairs, Downy Lobelia  has one of the largest flowers of the Lobelia genus.  The flowers are also characteristically arranged along one side of the  stem, which gives  them a slightly unbalanced look.  Below are photos of the flowers and fuzzy stem of several of these plants.  The true color of these flowers was hard to capture in digital images.  The last photo of the following three represents the true color of the flowers.

Lobelia puberula Downy Lobelia Flowers

Lobelia puberula
Downy Lobelia
Flowers

Lobelia puberula Downy Lobelia Stem and Leaf

Lobelia puberula
Downy Lobelia
Stem and Leaf

Lobelia puberula Downy Lobelia Flower

Lobelia puberula
Downy Lobelia
Flower

Mushrooms are also common along the roadsides just past the entry gates.  The mushrooms pictured below are Amanita muscaria , Fly Agaric, which are considered both toxic and hallucinogenic.  These are most likely the Southeastern variety, Amanita muscaria var persicina, which tend to be yellow and orange rather than red.   Thanks to Van Cotter for the I.D.!

Amanita muscaria var. persicina Fly Agaric

Amanita muscaria var. persicina Fly Agaric

 

Amanita muscaria var. persicina Fly Agaric

Amanita muscaria var. persicina
Fly Agaric

Amanita muscaria var. persicina Fly Agaric

Amanita muscaria var. persicina
Fly Agaric

And finally, the Slenderleaf False Foxglove (Agalinis tenuifolia).   Twelve consecutive days of rain in late September and early October have beaten many of these fragile plants down, making them more difficult to see.  The leaves and stems are very narrow, and the pink flowers are small but bright.  Grassy roadsides and ditches are perfect for these annual wildflowers, since they are semi-parasitic on grass roots.  In the photograph below, note the drooping position of the two upper flower petals.  This characteristic helps to differentiate Slenderleaf False Foxglove from its close relatives.

Agalinis tenuifolia Slenderleaf False Foxglove Flower

Agalinis tenuifolia
Slenderleaf False Foxglove
Flower

 

Herb Amyx

Update:

A question was asked about Helianthus atrorubens, the Purpledisk Sunflower.  Why is it called Purpledisk ?  There really doesn’t seem to be anything purple about it.

A close up of the disk itself reveals that the tiny disk florets are a dark red, which can be interpreted as purple.

Helianthus atrorubens Purpledisk Sunflower Close View of Disk

Helianthus atrorubens
Purpledisk Sunflower
Close View of Disk

According to the dependable website alabamaplants.com,  “atr” is derived from the Latin for black and “rube” from the Latin for red or reddish.  When combined into “atrorubens” they become “dark red”.

 

 

 

 

 

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Helianthus porteri (Porter’s Sunflower) Survives Drought at Rocky Face Mountain

Helianthus porteri, Porter’s Sunflower, is a highly specialized sunflower endemic to the harsh conditions of granitic outcrops.  It is found at only two  sites in North Carolina.  One of these is a low elevation granitic dome called Rocky Face Mountain, in Alexander County.  In mid September, Alexander and  surrounding counties in the Northern Piedmont were in the grip of a serious drought.  Even Helianthus porteri was affected, and the fall bloom subdued.

Rocky Face Mountain, A Low Elevation Granitic Dome

Rocky Face Mountain,
A Low Elevation Granitic Dome

Helianthus porteri was by far the most visible of the endemic plants at Rocky Face Mountain, and its yellow blooms were seen throughout the base, slopes and top of the granite dome, although in reduced numbers this year.  The group pictured below at the base of the dome was blooming well, even while the foliage was withering and drooping.

Helianthus porteri Porter's Sunflower Bloomin

Helianthus porteri
Porter’s Sunflower
Blooming

The H. porteri  on the slopes were not faring as well, especially those at the top of the slopes.  Some clusters of plants had died, but most were still surviving.  The following plants were typical of many seen – badly stressed but capable of complete recovery with a little rain.  In the first photo, the slope behind and the small patch of soil containing the plants can be seen.  The second photo is a closer view of the plants.

Helianthus porteri Porter's Sunflower Badly Stressed

Helianthus porteri
Porter’s Sunflower
Badly Stressed

Helianthus porteri Porter's Sunflower Badly Stressed

Helianthus porteri
Porter’s Sunflower
Badly Stressed

Some of the non-endemic plants, like the American Beautyberries (Callicarpa americana), were in a terminal, dehydrated state, especially those with a full sun exposure.

Callicarpa americana American Beautyberry Dehydrated and Dying

Callicarpa americana
American Beautyberry
Dehydrated and Dying

From the base of the dome, a group of H. porteri could be seen blooming at the top of the cliff.

Helianthus porteri Porter's Sunflower At Cliff's Edge

Helianthus porteri
Porter’s Sunflower
At Cliff’s Edge

A view of the same group from the top of the dome revealed that the plants were rooted in a large, horizontal crack in the granite.  They were also located at the base of an elevated slope, in a perfect position to catch moisture that would run down the slope from  light showers.  These plants looked normal and were well hydrated even though exposed to full sun.

Helianthus porteri Porter's Sunflower View From the Top

Helianthus porteri
Porter’s Sunflower
View From the Top

Another healthy group of H. porteri was seen growing from the convergence of two  cracks, where rain water would run down from two sections of the slope to flow into the cracks.

Helianthus porteri Porter's Sunflower Growing From Cracks in the Granite Dome

Helianthus porteri
Porter’s Sunflower
Growing From Cracks in the Granite Dome

Even without the advantage of a slope to bring moisture, several clusters of H. porteri were growing from cracks in a horizontal surface of the granite.   Whatever amount of soil was present in the granite cracks, it was completely protected from the drying effects of direct sun.  In full sun exposures, the plants growing from cracks in the granite were clearly doing better than those growing in the patches of soil on  the granite surface.

Helianthus porteri Porter's Sunflower Growth From Horizontal Cracks

Helianthus porteri
Porter’s Sunflower
Growth From Horizontal Cracks

Phemeranthus teretifolius, the Quill Fameflower or Appalachian Rock-pink, was another endemic plant that was surviving the drought well.  Its summer green color had turned to an autumn red, but the plants looked well hydrated.   A large group were found growing in an area of hardened gravel at the base of the dome.  Remarkably, it was difficult to scrape up any soil at all in this area, which looked like the surface of a gravel road.

Phemeranthus teretifolius Appalachian Rock-pink

Phemeranthus teretifolius
Appalachian Rock-pink

Helianthus porteri is somewhat unusual in that it is an annual  in a genus that is mostly perennials.  During his Ph.D. work at the University of North Carolina at Chapel Hill, Abram Mellinger  built an artificial granite flatrock to establish and study a colony of Helianthus porteri.  He soon had a large, flourishing colony which he maintained and studied over a period of years.  In 1968, a prolonged and extreme drought resulted in the deaths of all the plants before they were able to set seed.  The next spring, the colony was completely restored naturally from the seed bank that it had established over the previous  years.

Helianthus porteri is not native to North Carolina, but was brought accidentally from Georgia to Rocky Face Mountain and the flat rocks of Mitchell Mill in Wake County in 1959, as part of an ecological experiment that focused on Diamorpha smallii (Elf Orpine).  For over 50 years, Helianthus porteri has remained and thrived in these two locations.

Herb Amyx

Mellinger, A. C.  1972   Ecological Life Cycle of Viguiera porteri and Factors Responsible for Its Endemism to Granite Outcrops of Georgia and Alabama  Ph.D. Thesis, UNC at Chapel Hill Botany Department

Note that Viguiera porteri was an older designation, which was reclassified to Helianthus porteri.

 

 

 

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Portulaca amilis (Paraguayan Purslane) : A Tropical Immigrant to North Carolina

Portulacas in the Southeast are annuals that have succulent leaves and stems.  They are often prostrate and branched, and have small, bright flowers with a very short blooming period.  The majority of Portulacas are tropical or subtropical in distribution.  There are only seven species in the Southeast, with the greatest concentration occurring in Florida.

The rarest of the Southeast group is Portulaca smallii, an inhabitant of granitic flatrock communities, which was featured in an article here last November on the Mitchell Mill State Natural Area.  In that article, peripheral mention was made of another Portulaca on the flatrocks and roadsides near Mitchell Mill.  Thanks to a reader, Bryan’s, suggestion, the plant has now been correctly  identified as  Portulaca amilis , Paraguayan Purslane, an introduced species from South America.   This summer, Portulaca amilis was confirmed at Mitchell Mill and the surrounding roadsides.  A check of the nearby Rolesville flatrocks and of disturbed areas in eastern Wake County found only P. amilis.  It tends to be found in sandy soil in disturbed areas, roadsides, fields, lawns and gardens.  The photo below shows a typical colony at the Rolesville flatrocks.

Portulaca amilis Paraguayan Purslane

Portulaca amilis
Paraguayan Purslane

In Northhampton County, which borders Virginia, Portulaca amilis is a common lawn weed.  It also appears in large colonies along the walkways north of the Roanoke River, as seen  below.

Portulaca amilis Paraguayan Purslane In a Residential Lawn

Portulaca amilis
Paraguayan Purslane
In a Residential Lawn

Portulaca amilis Paraguayan Purslane Walkway North of Roanoke River

Portulaca amilis
Paraguayan Purslane
Walkway North of Roanoke River

Portulaca amilis Paraguayan Purslane Walkway North of Roanoke River

Portulaca amilis
Paraguayan Purslane
Walkway North of Roanoke River

The flowers of P. amilis are an intense, deep pink, very striking and attractive.  The flowers bloom for only a single day and only for a few hours.  Otherwise, they would be a desirable addition to a garden.  As seen in the close up below, the flowers have many stamens (tipped with yellow pollen) and the  stigmas have multiple branches (seen in the center of the flower).

Portulaca amilis Paraguayan Purslane Flower

Portulaca amilis
Paraguayan Purslane
Flower

 

Below are  seed capsules opened to show the typical black, shiny, round seeds of P. amilis.

 

Portulaca amilis Paraguayan Purslane Seeds

Portulaca amilis
Paraguayan Purslane
Seeds

The native range of Portulaca amilis is widespread in South America, including parts of Brazil, Paraguay, Uruguay, and Argentina.  It first arrived in the United States in North Carolina, an unusual occurrence, particularly since the first reports were inland, and not at the coast.  In 1981, Judd and Wunderlin reported that the earliest herbarium collection date they had seen was in 1956 from Harnett County, which is in central North Carolina.  Later, in 1985 , Matthews and Levins reported finding what remains today the earliest collection : 1932 in Robeson County, North Carolina, on the border with South Carolina.   They also hypothesized that P. amilis seeds may have “…hitchhiked from South America following a military exercise…” and become established at Ft. Bragg and other military bases near Fayetteville, North Carolina.   From there it has spread north to Virginia, south to Florida and west to Louisiana.

Thanks again to Bryan for calling attention to  this interesting history in his comments.

Herb Amyx

References:

First Report of Portulaca amilis (Portulacaceae) in the United States, Walter S. Judd and Richard P. Wunderlin, SIDA, Contributions to Botany, Vol 9, No 2 (November 1981), pp. 135-138

The Genus Portulaca in the Southeastern United States.  James F. Matthews and Patricia A. Levins, Castanea, Vol 50, No 2 (June, 1985), pp. 96-104

 

 

 

 

 

 

 

 

 

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The Japanese Pagoda Tree and the Giant Resin Bee – Asian Species Reunited in North America

The Japanese Pagoda Tree (Styphnolobium japonicum) is an ornamental tree introduced from Asia, and  best known for its showy bloom in late summer, long after the flowering period for most trees.  A beautiful specimen can be found at Falls Lake, in the Blue Jay Point County Park.  At peak flowering, the tree can be located by following the loud thrumming sounds of the visiting  pollinators.  The masses of flowers attract a variety of bees and bumblebees, which arrive in very high numbers.  Their frantic activity causes a constant rain of flower petal fragments that litter the ground all around the tree like a white skirt.

Styphnolobium japonicum Japanese Pagoda Tree

Styphnolobium japonicum
Japanese Pagoda Tree

Styphnolobium japonicum Japanese Pagoda Tree Clusters of Flowers

Styphnolobium japonicum
Japanese Pagoda Tree
Clusters of Flowers

Styphnolobium japonicum Japanese Pagoda Tree Clusters of Flowers

Styphnolobium japonicum
Japanese Pagoda Tree
Clusters of Flowers

The compound leaves and terminal flower panicles are beautiful and symmetrical when viewed from below.

Styphnolobium japonicum Japanese Pagoda Tree Compoud Leaves and Terminal Flower Panicles

Styphnolobium japonicum
Japanese Pagoda Tree
Compound Leaves and Terminal Flowers

 

Styphnolobium japonicum Japanese Pagoda Tree Compound Leaves

Styphnolobium japonicum
Japanese Pagoda Tree
Compound Leaves

The flowers are typical of the legume family (Fabaceae) and resemble those of the related Black Locust –  Robinia pseudoacacia.

Styphnolobium japonicum Japanese Pagoda Tree Flowers

Styphnolobium japonicum
Japanese Pagoda Tree
Flowers

The Giant Resin Bee (Megachile sculpturalis), present in high numbers on the tree, is by far the most numerous of the pollinators.  They are easy to see and identify due to their large size and cylindrical, elongated bodies.  See below.

Megachile sculpturalis Giant Resin Bee

Megachile sculpturalis
Giant Resin Bee

The massive mandibles present on the females are often easily seen when closely approaching the bee, and serve as an additional identifying characteristic.

Megachile sculpturalis Giant Resin Bee Mandibles

Megachile sculpturalis
Giant Resin Bee
Mandibles

The Giant Resin Bee is a member of the leafcutter bee family (Megachilidae), and the mandibles are mainly used to chew leaves and collect plant resins.

The Giant Resin Bee is an Asian species, introduced into the United States relatively recently.  It was first reported here in North Carolina in 1994 and has since spread widely throughout the Southeast.   It is one of the main pollinators of the Japanese Pagoda Tree in China and Japan, and since its introduction into North Carolina, it reunites with the tree once again on scattered streets and in parks.  On the dark side, it also pollinates the highly invasive Kudzu and Purple Loosestrife in their native home in Asia, and in the United States.  Obviously neither of these species need further help, so the impact on them is probably limited.

Giant Resin Bees visit my backyard every summer, where they completely commandeer a Mason Bee nest block.  In the photo below, the shiny, silvery plant resins can be seen plugging the bottom three holes on the left.  The bees form pollen into balls, place the balls into the holes in the nest, and lay their eggs on the pollen ball.  They then seal the hole with the plant resins.

Plant Resins on a Mason Bee Nest Block

Plant Resins on a Mason Bee Nest Block

Giant Resin Bees are solitary, but  sometimes  interact when they are building  a nest.  They often pay little attention to each other, but they sometimes quarrel over a particular hole.  In the sequence below, a female can be seen starting to pull another female out of a hole.

Megachile scupturalis Giant Resin Bee

Megachile scupturalis
Giant Resin Bee

Below, she finally succeeds in dragging the other female out of the hole.

Megachile scupturalis Giant Resin Bee

Megachile scupturalis
Giant Resin Bee

They face off and clash for awhile, but don’t do any real harm to each other. This sequence was repeated several times before the aggressor finally tired of the game and selected her own hole.

Megachile scupturalis Giant Resin Bee

Megachile scupturalis
Giant Resin Bee

Giant Resin Bees are known to utilize the wooden tunnels vacated by Carpenter Bees.  Recently it has been reported that the Giant Resin Bee actively displaces Carpenter Bees in some areas.  One wonders if they evict Carpenter Bees in the same way as illustrated above.  Entomologists consider the recent introduction of Giant Resin Bees to have had a minimal impact on the environment, but time will tell.

The Japanese Pagoda Tree pictured in this article has shown no signs of spreading from its present location, and the species in general has had minimal invasive impact in the South.  However, it has become naturalized in spotty locations in the Midwest and Mid-Atlantic regions.

Herb Amyx

 

 

 

 

 

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