South Texas Part V: A Stop for a Sand Sheet Endemic


Amelia’s Sand Verbena blooms in the South Texas Sand Sheet

The South Texas Sand Sheet occurs across a handful of South Texas counties.  It consists of layer of loose sand that was blown inland from the Gulf of Mexico in the Holocene.  The sand sheet is home to a suite of endemic plant species.  Perhaps the most spectacular is the Amelia’s Sand Verbena (Abronia ameliae), which can be found nowhere, save the South Texas Sand Sheet.


Amelia’s Sand Verbena

While returning home from the Rio Grande Valley we passed through the sand sheet.  I began seeing splashes of a deep pinkish purple passing as a blur at 75 miles per hour.  Finally after seeing a large field of pink I shouted “STOP!”  And my dad, despite his better judgement pulled over into the right of way of the busy highway and backed up to the spot that caught my eye.

The Amelia’s Sand Verbena was blooming en masse.  It was great to see such a rare, range-restricted plant thriving.  Recent rains may have helped provide such a spectacular bounty of flowering plants.  Growing among the sand verbena were a number of other South Texas specialties, including Rio Grande Phlox (Phlox glabriflora).


Amelia’s Sand Verbena


Amelia’s Sand Verbena and Rio Grande Phlox bloom in the South Texas Sand Sheet

It was a cool, overcast morning, so there were not many pollinators around.  We did however notices a stealthy predator nestled within the amble flowers on the inflorescence of one of the sand verbenas: a Crab Spider.


A Crab Spider hidden in the blooms of an Amelia’s Sand Verbena awaits a meal

Seeing these South Texas Sand Sheet endemics was the perfect ending to an incredible trip full of biodiversity.  I was sad that it was coming to an end, but I took comfort in the fact that there were many other natural wonders still waiting to be explored.


Common Plant, Uncommon Beauty

Target Species: Blue Curls (Phacelia congesta)


Blue Curls

Most of the species on my 2017 biodiversity list are rare, unusual, range-restricted, or hard to find.  I added Blue Curls (Phacelia congesta) simply because they are beautiful and I wanted to photograph them!  One might wonder how a species that can be prolific along roadsides eluded my lens for so many years, but these lovely spring wildflowers do not occur in the Pineywoods, and though I have most certainly passed by them at 75 miles per hour on the free way, I never took the time to stop and smell the Blue Curls, so to speak.


Blue Curls

Phacelia congesta is an iconic Texas wildflower, and is featured prominently in virtually every wildflower guide and photo tribute book covering the region.  In fact, the majority of its range is centered in the Lonestar State, and it just barely spills over into New Mexico and Oklahoma.  Blue Curls tend to occur on coarse sandy or gravelly soils, primarily in central, south, and west Texas.  Here it occurs in open brushlands, woodlands, savannahs, and roadsides.  In open areas it can form dense colonies, literally blanketing the ground with its light blue to purple blooms.  It is my experience that blue, pink, and purple flowers differ dramatically in how the reflect color under sunny vs. cloudy conditions.


Blue Curls, showing the buds along the curled inflorescences.

Phacelia congesta is a plant of many names.  I have seen it referred to as Caterpillars, Fiddleneck, Spider Flower, and Wild Heliotrope.  I chose Blue Curls for the blog, as it is the common name I have most frequently seen associated with this species.  To me, it is also the most fitting.  The flower buds are arranged on long, curled inflorescences.  As the flowers begin to open, the inflorescences slowly unfurl until all of the flowers have bloomed.


Blue Curls

I found this large group of Blue Curls on a Spring Break trip to South Texas with my family.  They were kind enough to indulge me much more than any normal patient person would (more on that in future blog posts).  The plants were much more robust, and even more spectacular than I was expecting.  We found them just after a rainy day had cleared to a beautiful afternoon, and I delighted in photographing several of the beautiful plants in this healthy population.


Blue Curls

Blue Curls was not the only species of Phacelia in the area.  We also found several individuals of Sand Phacelia (Phacelia austrotexana).  This one still had a few raindrops clinging to the bloom.  P. austrotexana was recently split from P. patuliflora.  It is restricted to South Texas and northern Mexico.


Phacelia austrotexana

Another South Texas endemic we found in the area was the Sand Brazos-Mint (Brazoria arenaria).  Carolina’s sharp eyes spotted this rare species.  It is a close relative to another species on my list, Brazos truncata, which I hope to photograph later this spring.


Sand Brazos-Mint


Sand Brazos-Mint

Rio Grande Phlox (Phlox glabriflora), another South Texas specialty, was also present.  Considered by some to be a subspecies of Phlox drummondii.  It is best differentiated by the later by its trailing stems.


Rio Grande Phlox


Rio Grande Phlox

Barely visible and easily overlooked among the larger, more showy wildflowers, were several blooms of Smallflower Milkvetch (Astragalus nuttallianus).  This species occurs at a few sites in East Texas, but it is rare there, so it was a treat to see it blooming by the thousands.  A slight breeze made photographing the tiny flowers a near impossibility.


Smallflower Milkvetch

Another widespread species that was present in good numbers was Berlandier’s Yellow Flax (Linum berlandieri).


Berlandier’s Yellow Flax

Checking Blue Curls off my list was a great way to start our trip to South Texas.  It was a sign of good things to come, I hoped.