The Enigmatic Dual Forms of Virginia Snakeroot (Endodeca serpentaria)

Virginia Snakeroot – Endodeca serpentaria –  is a common , low growing, native perennial that can be found in a variety of forest habitats in North Carolina.  It is a member of the Birthwort family (Aristolochiaceae) , a family primarily of tropical woody vines.  Virginia Snakeroot is a family outlier in that it is neither tropical, woody, nor a vine.  Its small size and low growing form make it very easy to overlook among other herbaceous plants on the forest floor.

Virginia Snakeroots are found in two different forms.  In this case, the form (forma) is part of its official taxonomic name.  Forma is the lowest taxonomic rank a plant can have and is rarely used.  It is the bottom of a descending rank of species, subspecies, variety, and forma.  Generally plants separated by forma differ only in minor characteristics like leaf color or shape.

Below are a series of photographs of Endodeca serpentaria forma hastata, which is the commonest one I see in Central North Carolina, but others may have a different experience.  These plants have smooth, narrow, spear-shaped leaves that sometimes have a flare at the base.  This shape is often called “hastate”, thus leading to the name.

Endodeca serpentaria forma hastata
Virginia Snakeroot
Plant Form

Endodeca serpentaria forma hastata
Virginia Snakeroot

Notice the small flowers on the ground near the base of the plant below.

Endodeca serpentaria forma hastata
Virginia Snakeroot
Plant Form

Endodeca serpentaria forma hastata
Virginia Snakeroot
Plant Form

The other form is called Endodeca serpentaria forma convolvulacea.  This form differs greatly from the preceding plants.  The leaves are more rounded and oval, and the entire plant is highly pubescent.  The plant below is a second year plant.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Plant Form

Seedlings are very tiny and are extremely slow to develop.  See below.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Seedling

The leaf margins are covered with fine hairs.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Pubescent Leaf Margins

The stems are covered with a dense pubescence in contrast to forma hastata, whose stems are almost completely smooth.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Pubescent Stems

Forma convolvulacea can form small colonies.  In the area around the largest plants, young seedlings and second year plants can be seen.  This small population is approximately 7 to 8 years old.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Small Population

It takes about 3  years before plants begin to flower.   They may then flower profusely, with clusters of flowers surrounding the base of the stems.  The flowers are also densely pubescent.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Cluster of Flowers

Several individual flowers are pictured below.  The location of the flowers in debris along the forest floor and the structure of the flowers themselves seem to point to pollination by small flies, fungal gnats and possibly carrion beetles.  But those facts may be deceptive.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Flower

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Flower

The structure, color and location of Virginia Snakeroot flowers are somewhat similar to their relatives in the genus Hexastylis (Ginger Heartleaf), who are in the same plant family.  See the photo of Hexastylis virginica below.

Hexastylis virginica
Virginia Heartleaf
Flower

Descriptions of the pollinators of Ginger Heartleaf bear a remarkable similarity to those of  Virginia Snakeroot.  For many years the assumption has been that both flowers produce fetid odors that attract various flies and perhaps carrion beetles.  It is now known, through actual scientific experiments, that Ginger Heartleaf flowers have no odor, and that they are primarily self pollinated.

Here is a quote from an article by W. John Hayden in the Bulletin of the Virginia Native Plant Society, 2010:  “So, things are not always as they seem. Wild gingers look like they ought to be cross pollinated by flies but the best available evidence is that only some species are and then only some of the time; self-pollination, whether autonomous(in Asarum) or insect-assisted (in Hexastylis) appears to be the norm for these curious plants.”   It certainly makes one wonder if the same might be true of Virginia Snakeroot.  We will have to await further studies to know the answer.

The flowers of forma convolvulacea produce seed capsules very quickly, usually in about a week.  The capsules in the photo below are clustered in the same manner as the flowers around the base of the stems.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Cluster of Seed Capsules

The capsules dry quickly and become very hard.  Each capsule has six valves, and six well-defined ridges can be seen on the surface of each capsule.  As can be seen below, they retain their pubescence after drying and detaching.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Seed Capsule

Below is another look at the dense pubescence, with the style still hanging on at the top of this particular capsule.

Endodeca serpentaria forma convolvulacea
Virginia Snakeroot
Seed Capsule

It would be of interest to know the distribution and specific habitats of the two separate forms, or whether they even have different habitats.  However, since they both appear in distribution charts simply as Endodeca serpentaria, those specific facts are unknowable.  We do know that only Endodeca serpentaria forma convolvulacea is found in New England, where it is rare and only found in Connecticut (  Allard, Dorothy J. 2002. Aristolochia serpentaria L. (Virginia Snakeroot) Conservation and
Research Plan for New England. New England Wild Flower Society, Framingham,
Massachusetts, USA. http://www.newfs.org)

The article on pollination mentioned earlier is :

Don’t Judge a Book by Its Cover: The Curious Case of Wild Ginger Pollination  by W. John Hayden    Bulletin of the Virginia Native Plant Society, Vol 29, No 1, Winter 2010.

Here is a link to the article:  https://scholarship.richmond.edu/cgi/viewcontent.cgi?article=1143&context=biology-faculty-publications

Herb Amyx

A special thanks to Bryan England for convincing me that  forma convolvulacea is really Endodeca serpentaria, and not a distinct species.

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