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

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

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

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 Star-wort
Massed Plants

Callitriche heterophylla Common Water-starwort 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

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

Advertisements
This entry was posted in Uncategorized and tagged , , , , , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s