Excerpts from Jim Conrad's
Naturalist Newsletter

Texas Bindweed, CONVOLVULUS EQUITANS, flower and leaves

from the the September 23, 2012 Newsletter issued from the valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the southern border of the Edwards Plateau, USA

In the Yucatan we had so many beautiful and remarkable members of the Morning-Glory Family that I got especially sensitized to the group. Therefore I was delighted when a morning-glory species I'd not seen before turned up tightly twining around the wire fence around my neighbor's pasture. You can see it above.

The blossom is small for a morning-glory, only a little over an inch across (3cm), and just look at how slender the arrow-shaped leaves are on the right, and notice how the leaf bases bear long "ears." A closer look at a leaf base is shown below:

Texas Bindweed, CONVOLVULUS EQUITANS, hastate leaf base

Such arrow-shaped leaves with narrow, backward-pointing ears, or "basal lobes," are said to be "hastate." And notice that these hastate leaves are particularly hairy with sharp hairs lying low against the leaf's surface. These are important field marks for this species. Another field mark is shown in the flower close-up below:

Texas Bindweed, CONVOLVULUS EQUITANS, flower close-up

The thing to notice there is that the female style is divided into two long, slender stigmas. Morning-glories that are members of the big genus Ipomoea have a spherical stigma very unlike this. Another field mark is the flower's unusual calyx with broadly overlapping sepals, shown below:

Texas Bindweed, CONVOLVULUS EQUITANS, calyx and sepals

So, all these eye-catching field marks mean that here we have the Texas Bindweed, CONVOLVULUS EQUITANS, found in much of the arid US Southwest and northern Mexico. It's closely related to a much more widely spread and weedier Bindweed, Convolvulus arvensis, which we met in Oregon, but our Texas plant's leaves are much narrower. You can compare our Texas one with the more common weedy species at http://www.backyardnature.net/n/h/bindweed.htm.

Birds eat Texas Bindweed's seeds, pollinators visit its flowers and bugs eat its leaves, but the plant is really too small and inconspicuous to make much of an impact on the usual human mind. To get a kick from it you have to be looking for special things in obscure little corners.