Infested Southern Hackberries (Celtis laevigata) in a Suburban Park

The Southern Hackberry (Celtis laevigata) is a common tree in the Piedmont of North Carolina, often occurring along rivers and streams, and in suburban parks.  In one large park near Falls Lake, and in the surrounding forests nearby, many Southern Hackberries are visibly discolored and ragged looking, as if someone had tossed a bucket of soot or ash over the foliage of the tree.  The two trees pictured below illustrate this appearance.

Celtis laevigata
Southern Hackberry
Tree With Sooty Mold

Celtis laevigata
Southern Hackberry
Tree with Sooty Mold

Closer examination of the foliage shows most of the leaves covered with a sooty mold.

Celtis laevigata
Southern Hackberry
Leaves with Sooty Mold

Examination of the undersides of the leaves reveals an extensive infestation of Hackberry Wooly Aphids (Shivaphis celti), an Asian species that may have been brought to the U.S. by the importation of Chinese Hackberries (Celtis sinensis).  The Hackberry Wooly Aphid secretes lavish amounts of honeydew, so much that the leaves and twigs become coated with the sticky substance.  The honeydew acts as a perfect substrate for the fungus – usually called sooty mold –  which covers the leaves.  The fungus does not kill the tree, but does cause some leaf drop.  The honeydew, which is rich in carbohydrates, attracts ants ,which do not harm the aphids but instead benefit them by protecting against predators.

Celtis laevigata
Southern Hackberry
Hackberry Wooly Aphid

Celtis laevigata
Southern Hackberry
Hackberry Wooly Aphid

The photos below provide several more views of the leaves covered with sooty mold.  Also seen are orange lady beetles that are present in small numbers on the affected trees.

Celtis laevigata
Southern Hackberry
Sooty Leaves with Lady Beetle

Celtis laevigata
Southern Hackberry
Sooty Leaves with Lady Beetle

The lady beetles are the Asian Multicolored Lady Beetle (Harmonia axyridis), a major predator of the wooly aphids.  They are badly outnumbered on the affected trees and have very little impact on the course of the infestation.  It is ironic that this prey and predator relationship that began in Asia continues in a similar setting on a distant continent where both species were introduced (the aphids by accident; the lady beetles both intentionally and accidentally).

Celtis laevigata
Southern Hackberry
Asian Multicolored Lady Beetle

The Southern Hackberries are also parasitized by Leaf Petiole Galls, caused by the Hackberry Petiole Gall Maker (Pachypsylla venusta).  Petiole is the botanical term for the leaf stalk.  These galls are very common on hackberries and do not kill the trees, even when present in large numbers, as they often are.  Several examples are pictured below.

Celtis laevigata
Southern Hackberry
Hackberry Leaf Petiole Gall

Celtis laevigata
Southern Hackberry
Hackberry Leaf Petiole Galls

There are also small numbers of fruits on the trees.  They can be distinguished from the galls by their smooth, symmetrical surface, reddish tint, and  their position at the end of a stalk.   The galls are always located between a leaf and a twig and are never at the end of a stalk.

Celtis laevigata
Southern Hackberry
Fruit

The leaves on these hackberries, and those in the surrounding forests, are quite variable.  Some have few to no serrations while others are serrated on each margin.  Weakley’s Flora (May 2015) now recognizes the hackberries that have significant serrated leaf margins as Celtis smallii, and it is possible that these trees and others at Falls Lake may fall into that category.

Herb Amyx

 

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The Neuse River Trail Heliotrope – Heliotropium indicum

Indian Heliotrope, Heliotropium indicum, is an introduced annual, probably from Tropical America.  It is uncommon in North Carolina, being absent from the Western Piedmont and the Mountains.  It is seen occasionally in small, isolated populations along the Neuse River Trail.  Unlike the garden Heliotrope (H. arborescens), which is known for its bright purple flowers and wonderful scent, Indian Heliotrope is considered an invasive and troublesome weed in many parts of the world.

Its small but beautiful flowers are reminiscent of Forget-me-nots, which are its close relatives in the Borage Family, the Boraginaceae.

Heliotropium indicum
Indian Heliotrope
Flowers

The flowers bloom in elongated, gracefully curved clusters, with the younger flowers occurring  near the end of the cluster, and the older flowers beginning to turn to  seed at the base.

Heliotropium indicum
Indian Heliotrope
Flowers

Photos of several populations are shown below.  Some are small and mingled with grasses at  ground level, and some are shrub-like, four to five feet tall.

Heliotropium indicum
Indian Heliotrope
Small Population

Heliotropium indicum
Indian Heliotrope
Large Population

Heliotropium indicum
Indian Heliotrope
Large Population

The typical plant form is illustrated by the two photos that follow.  The plants tend to be broad and low to the ground initially, rising in height as they begin to bloom.

Heliotropium indicum
Indian Heliotrope
Plant Form

Heliotropium indicum
Indian Heliotrope
Plant Form

The flower clusters can be elongated and very striking.   Their appearance gave rise to the common names Scorpion Weed and Scorpion Tail.

Heliotropium indicum
Indian Heliotrope
Elongated Flower Clusters

The leaves are broad and ovate, with a wrinkled upper surface, and are usually (but not always) alternate on the stem.

Heliotropium indicum
Indian Heliotrope
Leaf Front

Heliotropium indicum
Indian Heliotrope
Leaf Back

Heliotropium indicum
Indian Heliotrope
Stem

An interesting attribute of Heliotropes – their  flowers turn and follow the sun as it travels across the sky.  The name was based on the Greek for sun (Helios) and (trope) for turning or tropism.  Turnsole, an old English term with a similar meaning, is also another common name for Heliotrope, and is the common name used for Heliotropium indicum in Weakley’s Flora.

Herb Amyx

 

 

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The Troublesome and Often Dangerous Hairy Nightshade, Solanum sarrachoides

The Hairy Nightshade (Solanum sarrachoides ) is an introduced species from South America which is uncommon to rare in North Carolina.  It is listed as occurring in only five North Carolina counties.  With this plant, scarcity is a good thing.  Like many of its nightshade relatives (family Solanaceae), Hairy Nightshade is a serious agricultural pest  of potato fields and is poisonous to livestock across its range.  It was identified as the cause of death to a small group of Black and White Ruffed Lemurs at a zoo in California.  Three of these lemurs were released into a brand new outdoor natural enclosure, that unfortunately also contained a group of  Hairy Nightshade plants.  Twelve days later, one lemur was dead and the others in critical condition.  Eventually a second lemur died, but the third finally recovered.

Hairy Nightshades are summer annuals found in open areas, gardens, agricultural fields, and disturbed places.  They are large, densely pubescent plants covered with sticky, glandular hairs and small, white flowers.  The plant in the photographs below was found in a rural Wake County garden (bringing the county total to six).  In the following photo, an eight foot metal tape is stretched across the plant.  It measures eight feet in length, five feet in width, and 2 feet high – a huge plant.

Solanum sarrachoides
Hairy Nightshade
Plant Form

The leaves and stems are soft and clammy to the touch.  The leaves are ovate to  nearly triangular in shape with small lobed margins.  It is impossible to touch or handle the plant without getting a sticky residue on the hands.

Solanum sarrachoides
Hairy Nightshade
Foliage

Solanum sarrachoides
Hairy Nightshade
Leaves

The flowers are fairly typical for nightshades with 5 white petals that are fused at the base.  A column of 5 stamens rise out of a green area at the base of the petals; the green style can be seen slightly protruding from the stamens.

Solanum sarrachoides
Hairy Nightshade
Flowers

The fruit is a rounded berry that usually remains green even when mature.

Solanum sarrachoides
Hairy Nightshade
Berries

Dense glandular hairs are the most notable characteristic of  Hairy Nightshades.  Another common name for the plant is Viscid Nightshade.  The glands appear to be stipitate glands, simply meaning that the glands occur at the end of stalks.  The following photos are closer views of the glandular hairs.  Note in the final two photos the globes of fluid visible at the ends of the stalks.  It is believed that these glands evolved as a means of transporting toxic wastes out of the plant body, where they serve as an early line of defense against insect or mammalian predators.

Solanum sarrachoides
Hairy Nightshade
Glandular Hairs

 

Solanum sarrachoides
Hairy Nightshade
Glandular Hairs

 

Solanum sarrachoides
Hairy Nightshade
Glandular Hairs

Our commonest North Carolina nightshade is the ubiquitous Horse Nettle (Solanum carolinense), found in large numbers everywhere in North Carolina.

Solanum carolinense
Horse Nettle
Plant Form

As the name implies, Horse Nettle has arrays of sharp, tough spines on the stems and  middle leaf ridges.

Solanum carolinense
Horse Nettle
Nettles

The flowers are larger than most nightshades and color can range from white to a light or deep violet.  The berries turn bright yellow in the fall and winter, and stand out against the bare winter landscape.

Solanum carolinense
Horse Nettle
Flower

The basis for the toxicity of these two plants and other nightshades is a glycoalkaloid called solanine, which is found throughout the plant and berries.  Toxicity varies tremendously depending on many factors, especially environmental  and genetic.   All are potentially dangerous when ingested.  In general, the berries are more toxic when they are young and the foliage is more toxic when it is mature.  The lemurs mentioned earlier in the article are vegetarians, but primarily fruit eaters.  So it is likely that they ingested berries rather than leaves.

Herb Amyx

 

 

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Flatrock Pimpernel – Lindernia monticola – in North Carolina

Lindernia monticola, Flatrock Pimpernel, is a small native perennial primarily associated with granitic flatrock and outcrop plant communities in North Carolina.  It is listed by the Natural Heritage Program as a Watchlist 1 plant with a rank of S2 – (Imperiled).  Watchlist 1 plants are rare, but are considered relatively secure and do not require specific site monitoring.  Lindernia monticola is one of only two species of Lindernia in North Carolina, L. dubia being the other.  Both are members of the Linderniaceae family, sometimes known as the false pimpernels.  Another common name for L. monticola is Piedmont False Pimpernel.  Below is a photo of a small population seen at a granitic flatrock in early May, in Wake County, NC.

Lindernia monticola
Flatrock Pimpernel
Population

As seen below, the leaves are short and elliptical, and are found almost entirely in a basal rosette.

Lindernia monticola
Flatrock Pimpernel
Basal Leaves

As the stems shoot upward, the leaves become greatly diminished until they are barely visible.  As the two photos below illustrate, even at the margins of the flatrocks, there remains enough soil depth to support competitive grasses and sedges.

Lindernia monticola
Flatrock Pimpernel
Stems and Flowers

Lindernia monticola
Flatrock Pimpernel
Stems and Flowers

The flowers are illustrated in the two exposures below.  The two lobes of the upper lip of the flower, as well as the three lobes of the bottom lip can be easily seen.  The basal leaves are said to be glandular and punctate.  The flower in the second photo appears to show similar characteristics.

Lindernia monticola
Flatrock Pimpernel
Flower

Lindernia monticola
Flatrock Pimpernel
Flower

The genus Lindernia was named for Franz Balthazar von Linden (1682-1755), a German botanist, artist and physician.*

There are various definitions of pimpernel.  The one that fits this purpose best is a plant belonging to the primrose family, especially the scarlet pimpernel – Lysimachia arvensis, which is a non-native.  It would be logical that a false pimpernel would be a plant that looks like a pimpernel but is something else.  However, the Lindernias and the primroses have entirely different flower forms, and it would be quite a stretch to mistake one for the other.   It would be interesting to know how the false pimpernel got its name.

Herb Amyx

*The Eponym Dictionary of Southern African Plants, 2006-2016, M. Charters, Sierra Madre, CA.   http://www.calflora.net/southafrica/plantnames.html

 

 

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Showy Orchis (Galearis spectabilis) Blooms at Rockcliff Farm

In early April, nearly one hundred Galearis spectabilis, the Showy Orchis, began to bud and bloom on a steep gorge within seventy five yards of the Wells house at Rockcliff Farm.  The most remarkable part of this orchid irruption is that a blooming Galearis spectabilis had not been seen in recent years.  It was not found during an extensive vegetation survey of Rockcliff Farm done in 2005, and had not been reported from the many wildflower walks conducted there over the past 10 years.  Below is a blooming Showy Orchis from this group.

Galearis spectabilis
Showy Orchis

So what were the circumstances that made this  sudden bloom possible?

One clue comes from observations made last year.  In early April 2016, a group of plants with two round, wide leaves were seen on the rich hardwood slopes of a steep-walled valley located about a mile from Rockcliff Farm.  One of these, with a developing bud, is pictured below.  In the photo, there appear to be three leaves because the plants are often right next to or on top of each other.  So there are actually two plants in the photo.

Galearis spectabilis
Showy Orchis
Basal Leaves and Bud

The plants were visited five days later to observe the bloom, but unfortunately deer had eaten the entire group of plants.  The same plant pictured above is shown below.

Galearis spectabilis
Showy Orchis
Plant Eaten by Deer

This year in early March, about 30 orchids were found in the same area.  They were covered with plastic deer screen to protect them from browsing.   In April they began to bud and bloom into typical Showy Orchis.

But what about the orchids at Rockcliff Farm, that were not protected against deer browsing because the orchids were not known to be there?  One possible explanation is the serious wildfire that occurred at the B. W. Wells S.R.A. in early March, just adjacent to Rockcliff Farm.  The fire started in the main power line due to a tree falling across electrical wires.  The fire burned down to the edge of the lake from both sides of the power lines along the road, and was hot enough to kill trees and destroy all shrubbery and ground cover.  Thus the hypothesis is that this fire destroyed most of the deer browse in this area, and the deer moved on to greener pastures, leaving the orchids unharmed.

In fact, over-abundant deer populations have been blamed for orchid declines, and reductions in deer density have been associated with surges in orchid populations.  (See Knapp, W. and Wiegand, R. 2014. Orchid (Orchidaceae) decline in the Catoctin Mountains, Frederick County, Maryland as documented by a long-term dataset. Biodiversity Conservation. Volume 23, Issue 8, pp. 1965-1976.)

Below, buds can be seen developing in two intertwined Showy Orchis.

Galearis spectabilis
Showy Orchis
Flower Buds

 

Galearis spectabilis
Showy Orchis
Flower Buds

The upper hood of the flower is formed by lateral petals and sepals.  The lower petal is large and white (a good landing place for bumblebees) and forms a spur at the rear.

Galearis spectabilis
Showy Orchis
Flowers

At the rear of the white lip is a hole that leads to a small nectar chamber (nectar reward).  Bumblebees can extend their tongues through the hole to reach the drop of nectar.  In the photo below, a small fly appears to have found the nectar.

Galearis spectabilis
Showy Orchis
Nectar Reward With Fly

Although Showy Orchis is very widespread, extending all the way from Canada to Georgia and into the Midwest, it is considered uncommon to rare in most of its range.

Herb Amyx

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Bird’s-Foot Violets (Viola pedata) on the Road to Rockcliff Farm

A sunny, roadside ditch is not the place you would normally expect to find colorful, showy violets, but that is exactly the environment that Viola pedata, the Bird’s-Foot Violet, prefers.  Patches of this violet were seen recently during a roadside trash pickup on both sides of the main road leading into Rockcliff Farm.   See below.

Viola pedata
Bird’s-Foot Violet
Flowers and Plant Form

The leaves of Bird’s-Foot Violet are deeply divided into narrow lobes, reminiscent of the toes of a bird.  Another common name sometimes used is Crow Foot Violet.

Viola pedata
Bird’s-Foot Violet
Leaves

Viola pedata , the Bird’s-Foot Violet, differs from other violets in a number of ways:

  1.  The plants prefer dry, sunny locations versus the moist, partially sunny to shady spots that most other violets need.
  2. The flowers are larger than other violets.
  3. Unlike other violets, they do not produce cleistogamous flowers.  This is especially unusual since the largest genus of cleistogamous plants is Viola.  Cleistogamous flowers are those that self pollinate, and propagate by producing specialized flowers that never open.
  4. They do not have the specialized hairs near the throat of the flower that other violet species have.
  5. They thrive in nutrient poor, relatively dry soils, while most violets prefer nutrient rich, moist soils, typical of rich hardwood forests.

Viola pedata has several natural color variations in the wild.   Adapted varieties  are  popular in horticulture, especially in rock gardens.

Herb Amyx

 

 

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Heritage Day is April 8th at Rock Cliff Farm

The B. W. Wells Association will host Heritage Day at  Rock Cliff Farm, B. W. Wells State Recreation Area, 1630 Bent Road, Wake Forest, North Carolina, on Saturday, April 8, 2017, from 10:00 am to 4:00 pm, Rain or Shine.  There are no admission fees.  Heritage Day features history and nature walks, an hourly plant raffle, and children’s games and activities.

Dr.Wells and his wife Maude were loved and respected by the neighboring families in the rural community where they spent their retirement years at Rock Cliff Farm.  He taught the children how to make baseballs, how to paint with homemade pine needle brushes, and how to make and fly kites.  These crafts, and others, are part of the children’s activities on Heritage Day.

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Bertram Whittier Wells was a pioneer ecologist and botanist.  He was a historically important figure as a proponent of studying plants as part of a natural community rather than as isolated individuals.  His book, The Natural Gardens of North Carolina, published in 1932, is a classic work on the natural history of North Carolina.

The following anecdote is taken from Nature’s Champion: B. W. Wells, Tar Heel Ecologist by James Troyer:

Dr. Wells tried to make botany understandable and interesting to the average person.  He invented common names that differed from those in contemporary botanical manuals.  He wanted the common name to help the observer remember the flower or plant.  Most of his names have been lost to time, but the one that remains and is still in use in botanical manuals is Green and Gold, Dr. Wells’, name for Chrysogonum viginianum.  It is pictured below.

Chrysogonum virginianum
Green and Gold

Herb Amyx

 

 

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