Common Water-starwort (Callitriche heterophylla) at the Mitchell Mill S.N.A.

Contrary to most of the aquatic weeds at the Mitchell Mill State Natural Area, Common Water-starwort, Callitriche heterophylla, is a native plant and is not considered invasive.  It is a small and relatively fragile plant that inhabits the quiet pools of the higher granitic flat rocks, away from the scouring floods of the Little River.  In his 1932 classic The Natural Gardens of North Carolina, B. W. Wells recommended this aquatic plant for ponds in his chapter on Native Wildflowers for the Garden.

The following photo illustrates a large flat rock pool with a population of Common Water-starwort.  The main colony is seen primarily on the left side of the pool.

Callitriche heterophylla
Common Water-starwort
Granitic Flat Rock Pool

In the Common Water-starwort, floating and submersed leaves have very different forms.  The underwater leaves are linear while the floating leaves are much wider and shorter, oval or spatulate (spoon shaped).  In the picture below, taken in December 2015, most of the plants show the linear, submersed form with only a few of the floating, wider leaved forms present.  The plants are annuals, and just developing over the winter.  Small plants that have recently germinated can be seen at the periphery of the main colony.

Callitriche heterophylla
Common Water-starwort
Linear Leaves

A closer view of a small plant illustrates the difference in leaf shape.  A recently germinated plant can be seen at the bottom right.

Callitriche heterophylla
Common Water-starwort
Both Leaf Forms

As the plants grow and spread in the spring, they begin to mass together, as seen below.

Callitriche heterophylla
Common Water Star-wort
Massed Plants

Callitriche heterophylla
Common Water-starwort
Massed Plants

A closer view of fully mature plants shows the typical rounded rosettes of the surface leaves.

Callitriche heterophylla
Common Water-starwort
Closer View of Surface Leaves

Flowers of the Common Water-starwort are located in the leaf axils.  They are small and lack petals and sepals.  But the plants are remarkably effective at dispersing pollen – by wind when the flowers are above the water, and by water when they are submersed.

Callitriche heterophylla does have a European relative that looks very similar but is not such a good citizen.  The European Water-starwort, Callitriche stagnalis, is both alien and invasive in the U.S.  Fortunately, it is not found in North Carolina.

Herb Amyx

A Trio of Lilliputian Spring Bloomers: Field Speedwell, European Corn Salad, and Small-flowered Forget-Me-Not

In April, when there are so many spectacular dogwoods, azaleas, and other large plants blooming, why would anyone be looking for spring blossoms skimming the surface of the ground?  No wonder the three tiny plants mentioned in the title go virtually unnoticed due to their small size and miniature blossoms.  Recently, all three were seen blooming together by the thousands over large portions of the Wake Forest Reservoir Dam in Wake Forest, North Carolina.

Veronica arvensis – known as Field Speedwell or Corn Speedwell, is by far the most common of the three.  It ranges throughout all the geographic areas of North Carolina.  A member of the Plantain family (Plantaginaceae), it is one of North Carolina’s most numerous non-native winter annuals.  The blue and white, four-petaled flowers are only a few millimeters across, less than an eighth of an inch.

Veronica arvensis
Field Speedwell
Flower

Valerianella locusta – European Corn Salad, is an introduced annual, a member of the Honeysuckle family (Caprifoliaceae).  It is much smaller and not as well known as its close relative Valerianella radiata , Corn Salad, which is a common and easily identified weed of open fields.  V. locusta is found in the Central Piedmont, but absent from the Coastal Plain and spotty in the Mountains.  In Europe it is often called Miniature Corn Salad.  As the name implies, it is edible and used in salads.  A group of blooming plants are pictured below.

Valerianella locusta
European Corn Salad
Group of Plants

The tiny individual flowers of V. locusta are a light blue in color (seen in the closer views below) in contrast to the white flowers of V. radiata.

Valerianella locusta
European Corn Salad
Flowers

Valerianella locusta
European Corn Salad
Closer View of Flowers

Myosotis stricta – Small-flowered Forget-Me-Not, is an introduced annual from Eurasia, a member of the Borage family (Boraginaceae).  Unlike the previous two plants, M. stricta is primarily a Northeastern species with a very limited distribution in North Carolina, where it is listed in only five counties.  It is not listed as occurring in Wake County, where these photographs were taken.

Most of the plants have a stiff, upright plant form, which led to the species name “stricta”, meaning stiff.

Myosotis stricta
Small-flowered Forget-Me-Not
Upright Plant Form

As the plants begin to flower, some display a graceful, arching form at the top, similar to some other members of the Borage family.

Myosotis stricta
Small-flowered Forget-Me-Not
Arched Plant Form

The tiny blue flowers are only a few millimeters across and appear as a small blue dot when seen from five or six feet away.  The plants are very pilose (hairy), as can be seen in  the photo below.

Myosotis stricta
Small-flowered Forget-Me-Not
Closer View of Flower

Herb Amyx

 

 

 

Spring Flowers of the Sweet Gum Tree – Liquidambar styraciflua

Sweet Gums (Liquidambar styraciflua) are among the commonest trees in the South, and are found in huge numbers throughout the Piedmont and Coastal Plain of North Carolina.  Although the spring flowers are fairly large, they are held high in the tree and are difficult to see.  An occasional low-hanging branch reveals an active cluster of early leaves and specialized flowers.  Sweet Gums are monecious (having both male and female flowers), but unlike Elms, both sexes are not found within a single flower – each sex has its own separate flower.  In the photo below, the leaves of the Sweet Gum are unfurling while the male flowers (staminate flowers) are clustered above the leaves and the female flowers (pistillate flowers) are suspended below the leaves.

Liquidambar styraciflua
Sweet Gum
Flowers and Unfurling Leaves

A closer look at the male flowers shows large numbers of very small flowers gathered in clusters on a thick stalk above the branch.  Sweet Gums are wind pollinated, and these flowers produce huge quantities of pollen.  Fortunately the pollen is only mildly allergenic and not a major cause of spring hypersensitivities.

Liquidambar styraciflua
Sweet Gum
Male Flowers

While most people will never see the colorful male flowers on the tree, they certainly see them underfoot, on sidewalks, patios, decks, driveways, and lawns, where they appear by the thousands, perhaps by the millions, every spring.

Liquidambar styraciflua
Sweet Gum
Male Flowers

The female flowers remain on the tree, suspended as a single, spherical structure with masses of tiny flowers.  The curled, tubular structures covering the surface are the stigmas of the flower, whose surface is sticky to catch the pollen.

Liquidambar styraciflua
Sweet Gum
Female Flowers

During the summer , this soft and delicate structure is transformed into a hard, prickly, and complex fruit made up of seed capsules.  The “gum balls” are highly unpopular with homeowners trying to maintain their lawns and keep their sidewalks clear.  They are tough on bare feet and gather in such numbers as to make walking unstable.

Liquidambar styraciflua
Sweet Gum
Seed Capsule

There is a seedless, sterile cultivar called “Rotundiloba”, that has been grown and propagated (vegetatively of course) for commercial sale.  Its leaf lobes are rounded rather than pointed, giving it an odd, unnaturally smooth look to many eyes.  Interestingly, the original tree was a native found in North Carolina in the 1920s.

Herb Amyx

 

Brief Update: Black Vultures Nesting at the B. W. Wells S.R.A.

Each winter for the past five years, a pair of Black Vultures have nested in a hollow tree at the B. W. Wells S.R.A., at Falls Lake, North Carolina.  It is presumably the same pair each time, as Black Vultures are known to return to the same nest site year after year.  This year, they were still on the nest on March 29th, the latest date they have been seen there.

Hollow Tree Black Vulture Nesting Site

Even though it is late for this pair, March  29th remains well within the normal nesting period for Black Vultures (Coragyps atratus).  Adults spend more than 25% of their lives nesting.  Eggs are incubated (by both adults) for a month or more, and the chicks are cared for in the nest for an additional two months.  Families tend to  associate together throughout the rest of their lives.

When a nesting bird hears a disturbance, or footsteps approaching the tree, it flies up to the hole and looks out to keep watch, as pictured below.  If closely approached, the bird flies into the lower branches of a neighboring tree until the visitor leaves.  Disturbances are rare since this area is not on an indicated hiking trail.

Black Vulture at the Opening of the Nest Cavity

See the original story at: https://bwwellsassociation.wordpress.com/2014/12/22/black-vultures-are-thriving-in-north-carolina/

Herb Amyx

The Late Winter Elm – Hidden Beauty in Tiny Flowers

It is unlikely that Elm tree flowers would be mentioned  in a discussion about late winter/early spring wildflowers.  The flowers are tiny (about 1/4 inch long) and inconspicuous on most trees.  Elms are wind pollinated, so showy flowers are not needed to attract pollinators.  In Central North Carolina, Elms usually bloom in late February, well before the leaves come out, giving the pollen unobstructed flight in the gusty winds of late winter.

The Winged Elm – Ulmus alata – is the most common native Elm in the Falls Lake Area and the Central Piedmont.  Its flowers, sparse and widely spaced on the branches, are difficult for a passing observer to  see.  Below are several  flowers seen from only a foot away.

Ulmus alata
Winged Elm
Flowers

Occasionally a much heavier and more conspicuous bloom can be seen on a large, native American Elm – Ulmus americana. The flowers are still tiny, but are much more numerous.

Ulmus americana
American Elm
Flowers

Ulmus americana
American Elm
Flowers

Below is a closer look at the pendulous flowers of a  Winged Elm.   The flowers are monecious (Containing both male and female organs).  The male anthers, which carry the pollen, are numerous in this photo.  They are the reddish, rounded structures; red arrows point to several of the lower ones.  A yellow arrow points to the female pistil, which houses the ovary.   It is the greenish white fuzzy structure partially obscured by an anther.

Ulmus alata
Winged Elm
Flowers – Close Up

In the following photo, the flower bud scales (red arrow)  are open while the terminal leaf bud (yellow arrow) is still tightly closed.  The leaf buds will not open until weeks after the flowers have bloomed.  Note the white, fuzzy surface of the twig.

Ulmus alata
Winged Elm
Bud and Leaf Scales

A flower from an American Elm gives a better illustration of the female pistil.  In Elms, two carpels fuse together to create the pistil, which is then described as bicarpellate.    The fuzzy stigmas line the open jaws and catch the pollen, which is then transferred to the ovary.

Ulmus americana
American Elm
Fused Carpels

Winged Elms get their name from the flattened, corky structures that line many of the branches.

Ulmus alata
Winged Elm
Winged Branches

The branching pattern of the Winged Elm gives a skinny, contorted, almost scarecrow look to the tree that is enhanced by the corky wings.

Ulmus alata
Winged Elm
Branches

There are a surprising number of large, mature, healthy American Elms in the Falls Lake Area.  This has been attributed to the fact that the devastating Dutch Elm disease has had less of an effect in the southern parts of its range.  Also, the American Elm populations  do not form stands in this area, but are widely separated and buffered by trees of other species, preventing the spread of Dutch Elm disease.   One large American Elm is pictured below.

Ulmus americana
American Elm

Ulmus americana
American Elm
Trunk

Ulmus americana
American Elm
Branching

Elms have played an important role in the history of Europe.  In fact, Oliver Rackham devoted an entire chapter to Elms in his classic The History of the Countryside.  Here are a few short excerpts:

“They (Elms) are the most complex and difficult trees in western Europe, and the most intimately linked to human affairs.”

“Of the village of Fleury near Verdun, where a million men killed each other in World War One, not one stone remains upon another; but the village elms have grown again from  bits of root that lay near the surface of the cratered earth.”

Herb Amyx

All photographs were taken early in the first week of March, 2016.

 

 

European Water Clover (Marsilea quadrifolia) Visits North Carolina

Floating near the shore in a suburban lake in Wake County, North Carolina, is a colony of plants that look very much like a group of flooded shamrocks.  They are Marsilea quadrifolia, an aquatic fern commonly called European Water Clover or Water Shamrock.  Marsilea quadrifolia is an exotic fern, introduced from Europe.  It is well established in the Northeast, but is rare in the Southeast.    Below is a small group of plants floating at the surface of the water, and a close up of a single plant.

Marsilea quadrifolia
European Water Clover

Marsilea quadrifolia
European Water Clover
Close View

Marsilea quadrifolia is considered a Waif in North Carolina (Weakley’s Flora, May, 2015).  A Waif in botanical terms normally refers to an introduced, alien plant that is unable over time to sustain a persistent population, and therefore does not become naturalized.   Thus it does not appear on the Flora of the Southeast distribution map for North Carolina or its surrounding states, but has evidently been seen in North Carolina sometime in the past.

As seen in the photos below, the lake provides a stable habitat, with shallow, quiet waters where the plant can root in mud and sand, relatively undisturbed by water level fluctuations.  The two trees in the immediate background of the first photo are Bald Cypress (Taxodium distichum).

Marsilea quadrifolia
European Water Clover
Habitat

Marsilea quadrifolia
European Water Clover
Colony

When the water is shallow enough, the plants can stand erect, out of the water.  Note the fiddlehead (a fern’s curled frond) near the center of the picture.

Marsilea quadrifolia
European Water Clover
Erect Form

In suitable habitats, the plants also have a land form, erect in the mud or sand.  See below.

Marsilea quadrifolia
European Water Clover
Land Form

Marsilea quadrifolia is a popular aquarium and water garden plant.  Its sudden appearance in a lake or pond is usually attributed to an accidental or deliberate introduction.  It has also been known to be disseminated by waterfowl.

Aquatic ferns represent only a tiny and comparatively insignificant portion of the aquatic plants in the Eastern U. S.  Two other aquatic ferns have been described in North Carolina.  Azolla caroliniana , the Eastern Mosquito Fern, is a tiny, native, floating aquatic fern, uncommon but widespread in the Southeast.   Salvinia molesta, called Giant Salvinia, is considered an exotic noxious weed, and is rare in the Southeast.

Herb Amyx

All photographs were taken on December 26, 2015.  Hard freezes and ice in January disrupted the plants and left only bits of debris.  The roots are cold hardy and the plants should return in the spring.

 

Postscript to Frostweeds: Needle Ice

At the end of the third week in January, Central North Carolina experienced a severe winter storm, with snow, sleet, and freezing rain.  Warm weather began to prevail in the days that followed, and the ice and snow melted rapidly, leaving the ground saturated with moisture.   A series of overnight hard freezes then produced perfect conditions for natural ice sculptures to form, particularly ice extruded from porous soils, a phenomenon known as needle ice.  This phenomenon was mentioned briefly in the previous article describing natural ice sculptures produced by Frostweed – Verbesina virginica.  The conditions required for needle ice are the same as for plants that produce ice sculptures: temperatures above freezing below the ground surface interacting with air temperatures below freezing right at the surface of the ground.

The photo below is of an open, grassy field next to a parking lot.  What at first appear to be skiffs of remaining snow, are actually needle ice produced overnight from the hard freeze.

Needle Ice in an Open Grassy Field

A couple of closer views follow.

Needle Ice in a Grassy Field

Closer View of Needle Ice

The next photo shows more clearly the ice rising directly from the soil surface itself, often forming narrow ribbons.

Needle Ice Rising Directly From the Bare Soil

A closer view of the needles of ice show grooves in the extruded ice very similar to those produced by plants.

Closer View of Grooved Ice Needles

Ice formations produced by soils are much more common than those of plant origin.  However, there are sometimes entire winters when the conditions are unfavorable for ground ice as well, particularly  during dry winters when there is not enough moisture at the surface of the soil.

Herb Amyx