The Jewel of the Weches Formation

Target Species: Clasping Jewelflower (Streptanthus maculatus)


The bad news is that I’ve fallen way behind in my blogging.  The good news, however is that the last few months have been full of incredible experiences in the natural world that I look forward to sharing.  So as we are sweltering under near record heat waves, I will share a few posts from this spring, and reminisce about cooler times.

This first post addresses the third, and unfortunately last species from my list of biodiversity goals that I have checked off this year.  In early May I photographed the spectacular Clasping Jewelflower (Streptanthus maculatus) in East Texas.  This member of the mustard family (Brassicaceae) is very rare in Texas, known from only a few sites over the Weches formation in the eastern part of the state.  Here it occurs in a few scattered populations where the iron-rich formation has been exposed.  I learned of this particular population near the Anderson/Henderson County line from my friend Trey Anderson who had found them a few years ago while performing some work in the area.  They occur on a steep exposed hill with a mix of artificial clearings and stunted forest over gravelly Weches substrate.  This soil is extremely rich in iron and it shows in the color of the hillside.

The Weches Formation is part of a broader collection of geologic formations known as the Claiborne Group.  This group also includes the Yegua, Cook Mountain, Sparta, Queen City, and Reklaw Formations.  These occur along with the Weches Formation as a matrix in a broad area that encompasses a narrow band that stretches from Cass, Marion, Harrison, Rusk, Nacogdoches, San Augustine and Sabine Counties in the east along a curve down to Webb and Zapata Counties in South Texas.  (See a map here).

I have previously written a blog post about Weches Glades, a unique vegetative community that occur at a few sites in Nacogdoches, San Augustine, and Sabine Counties.  Streptanthus maculatus once occurred here as well, and can probably still be found at a few existing sites.  Many populations have been lost, however, to land use conversion and extensive glauconite mining.  Elsewhere in its range S. maculatus occurs over similarly iron-rich deposits in eastern Oklahoma and western Arkansas.

I was a bit late in seeking these jewels out this year, as most were already spent or in fruit.  The individual pictured was the only one I found in decent shape.  I’m not complaining though, for it gives me something to look forward to next year, and will afford me another visit to the unique, disappearing communities of the Weches Formation.

The Flora of Weches Glades

Target Species: Widow’s Cross (Sedum pulchellum)


Widow’s Cross

Weches Glades are unique communities in the Pineywoods that occur where the underlying Weches Formation reaches the surface.  Here lie exposed iron rocks and soil that are rich in glauconite, a greenish mineral composed primarily of iron and potassium.  Weches Glades occur in a narrow band stretching across Nacogdoches, San Augustine, and Sabine counties and are home to a unique flora, including species that are found nowhere else on the planet.

The coarse soil of the Weches Glades are often saturated in the spring and summer, occasionally forming shallow pools in small depressions in bare rock.  The heat and sweltering sun of summer quickly evaporates these pools, and leaves the soil dry and brittle.  In the spring the boulders at some of the few remnant glades turn light pink, awash with the blooms of the Widow’s Cross (Sedum pulchellum).

Widow’s Cross is a species of the South-Central states, from extreme Northeast Georgia, Tennesse, and Kentucky in the east to Kansas, Oklahoma, and Texas in the west.  It is generally limited to glades and outcrops, communities where little else can grow.  It thrives under shallow, harsh soil conditions.  As these communities are often limited across the landscape, Sedum pulchellum is generally uncommon to rare throughout its range.  In Texas it occurs in just a handful of counties in the northern and central portions of the state.  In the Pineywoods it is limited to Sabine and San Augustine Counties.


Widow’s Cross

Widow’s Cross owes much of its success in these environments to its succulent leaves, which can quickly absorb and store water from fall and winter rains in order to put on a spectacular spring show.  It’s easy to see how the plant gets its name.  It’s actually named for the cross like shape of the four-petaled flowers, however the inflorescence also often forms in the shape of a cross.


Widow’s Cross

Though Weches Glades were likely always infrequent and highly localized, a great deal have been lost to glauconite mining.  This mineral which seems critical for some species has long been used for soil enhancement and road filler.  As result small scale surface mining operations have destroyed many of these unique communities.  The vast majority of those that remain are on private land and site unprotected to this day.


Widow’s Cross

While I had previously photographed this species, I captured it on the tail end of its blooming cycle and the plants were past their prime.  This year I aimed to capture them at their peak.  While they generally bear 3 or 4-pronged racemes, I found some with 5 prongs.


Widow’s Cross

Weches Glades are also home to 2 endemic, Federally Endangered plants: The Texas Golden Gladecress (Leavenworthia texana) and the White Bladderpod (Lesquerella pallida).  Leavenworthia texana is endemic to Sabine and San Augustine Counties.  Here it occurs almost entirely on private land.  These diminutive plants bloom in early spring, ad by the time Widow’s Cross blooms they have already dispersed their seeds.  I photographed the individuals below in mid-February.  In the second photo the developing stems of Sedum pulchellum can be seen.


Texas Golden Gladecress


Texas Golden Gladecress

The White Bladderpod is restricted to a handful of Weches Glades in San Augustine County.  It is named for its spherical seed pods, which can be seen adjacent to the blooms on the photo below.  It was in full bloom at the same time as the Widow’s Cross.  Curiously, the bladderpod and gladecress generally don’t occur at the same outcrops.


White Bladderpod


White Bladderpot

While photographing the flora of the Weches Glades, one will immediately note the strong smell of mint that fills the air.  This is a result of dense populations of the Limestone Calamint (Clinopodium arkansanum).


Limestone Calamint

There are many other interesting species that can be found blooming in Weches Glades.  I leave you with a few of them.


Comanche Daisy (Astranthium ciliatum)


Drummond’s Stitchwort (Minuartia drummondii)


Pitcher’s Stitchwort (Minuartia patula)