Calystegia spithamaea ssp. stans – An Atypical Morning Glory

Calystegia spithamaea ssp. stans is an unconventional member of the Morning Glory family.   Unlike most members of the family (the Convolvulaceae), Calystegia spithamaea ssp. stans is neither an annual nor a twining vine, but a perennial with an erect growth habit.   Its common names are Low False Bindweed, Shale Bindweed, and Shale Barren Bindweed.  Due to its small size (usually a foot tall or less) and low growth habit,  it can be hard to find in heavy undergrowth.  Below is a flower peeking out of  grass with the rest of the plant hidden in the foliage.

Calystegia spithamaea ssp. stans Shale Bindweed Flower

Calystegia spithamaea ssp. stans
Shale Bindweed
Flower

Another plant, where the form can be seen a little better, is showing 3 buds visible on the stem above the open flower.

Calystegia spithamaea ssp. stans Shale Bindweed Flower and Buds

Calystegia spithamaea ssp. stans
Shale Bindweed
Flower and Buds

In an area with less undergrowth, the plant form can be seen much better, as in the two photos that follow.

Calystegia spithamaea ssp. stans Shale Bindweed Plant Form

Calystegia spithamaea ssp. stans
Shale Bindweed
Plant Form

Calystegia spithamaea ssp. stans Shale Bindweed Plant Form

Calystegia spithamaea ssp. stans
Shale Bindweed
Plant Form

The flowers arise from the leaf axils, and are symmetrical and trumpet shaped, similar to others in the morning glory family.  They also open in the early morning and close about mid-day.

Calystegia spithamaea ssp. stans Shale Bindweed Flower Arising from Leaf Axil

Calystegia spithamaea ssp. stans
Shale Bindweed
Flower Arising from Leaf Axil

 

Calystegia spithamaea ssp. stans Shale Bindweed Flower

Calystegia spithamaea ssp. stans
Shale Bindweed
Flower

According to Weakley’s Flora (2012), the stems and leaves of Calystegia spithamaea ssp. stans are tomentose, meaning that they have short, dense, matted hairs.  See below.

Calystegia spithamaea ssp. stans Shale Bindweed Tomentose Stem and Leaves

Calystegia spithamaea ssp. stans
Shale Bindweed
Tomentose Stem and Leaves

Another important characteristic is that the leaves tend to be folded upward from the midrib.  This upward fold is sometimes mild and sometimes quite pronounced, as seen below.

Calystegia spithamaea ssp. stans Shale Bindweed Folded Leaves

Calystegia spithamaea ssp. stans
Shale Bindweed
Folded Leaves

Calystegia spithamaea ssp. stans is currently a Watchlisted plant (W1 – rare but relatively secure) and is ranked S2S3, somewhere between imperiled and vulnerable, by the North Carolina Natural Heritage Program.  Since it is relatively secure, it does not merit protection by the State at this time.  All photos were taken in Durham County, North Carolina.

Herb Amyx

 

 

 

 

 

 

 

 

 

 

 

 

 

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