After my trip to Austin, Texas for the 2018 Garden Bloggers Fling (now called The Fling), I drove home via the scenic route. So much so, that I ran out of daylight long before I was home.
Meaning I regretted driving, until I looked back at my photos. Photos from May 7, 2018:
Adieu Austin –
SUB-HUMID SUBTROPICAL, Southern Prairie Parkland, 700 ft elev, 32″ precip
Flat Track was a mellow place to plan my trip home through gorgeous May weather. The BBQ each place before was amazing, which I feasted on following my Wednesday evening arrival and several more times that trip. So, I had to show that.
My roadtrip home actually started at least one-third of the way into Texas, if one traveled west, so was it a 2/3 transect?
This post didn’t include the ATX overkill of cor-ten steel, string lights, or over-confident plant use like Aussie-via-Tucson frozen shoestring fries acacias.
Such trends were far-outweighed by so much good design and plantsmanship there.
At the end of this post, I list my posts of some of the fine garden designs from that Austin trip. I decided to delete my old blog which had similarly good designs, many light on the designer’s touch, including down the road from past, enjoyable San Antonio trips.
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Back to metro Austin: it’s situated mostly on the flatlands and low hills of the verdant Blackland Prairie. That’s just below and east of the oak and juniper woods and savannahs of the Texas Hill Country, starting at the Balcones Escarpment – where Austin’s western burbs are located. The Hill Country is the wetter, eastern part of the expansive Edwards Plateau, which stretches from I-35 to the Pecos River. That’s where we’re headed, but indirectly, before we go through the drier, western part of the same Edwards Plateau. Only to twist into and out of a couple other regions before reaching the truly arid Chihuahuan Desert, that continues for the last several hours until I reached home.
The Texas Hill Country is a good example of a diversity hot spot for native flora. Some of its towns and those bordering it are also garden hot spots due to a horticultural culture. You’ll see my posts from this trip at the end of this post, to illustrate that:
I enjoy seeing the changes between ecoregions as I drive. Successful gardens are more often than not modeled after wild ecosystems within each ecoregion, then abstracted into their space and architecture.
I included a modified, improved ecoregions map at the end of this post, including a close-up map showing my route home.
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Onward, after picking up a dozen donuts in Round Rock for my coworkers the next day.
After negotiating a few stretches of freeway and arterial streets, and light mid-morning traffic into northwest Austin, I aimed my car west on Fitzhugh Road directly into a scene that might attract as many people to central Texas as a few days of SXSW.
As a desert dweller, where May is even drier than it already is October to April, imagine this for me.
The Texas Hill Country and the Eastern Edwards Plateau –
SUB-HUMID WARM-TEMPERATE, Southern Prairie Parkland, 1,400 ft elev, 28″ precip
Yeah. Cue this song from Austin resident, baritone extraordinaire Bill Callahan, and let it play in the background – here
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I passed by attractive ranch gates, Flat Creek with cool, limestone-filtered water flowing past sycamores and bald cypresses, native here and points east, plus exurban development. That’s as Hill Country today as are German hamlets and their dance halls.
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After a lunch stop in Johnson City, more ranch land is studded by plateau live oak savannahs and some woods, as I drive towards Fredericksburg to exit onto I-10 near Junction. This is all within sporadically yet well-watered lands considered sub-humid, but the landscape dries out faster to the west. Still with the same late spring warmth that feels perfect for my drive.
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Sonora and the Western Edwards Plateau –
SEMI-ARID WARM-TEMPERATE, Southern Plains Dry Savannah, 2,000 ft elev, 22″ precip
It’s warming up as I head west, looking like the start of early summer at home, where rain has little chance of greening up anything for 2 more months.
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Leaving Sonora I’m on the remote Juno Highway or TX-189, where the Hill Country overlaps into drier points to the west. But the transition or ecotone gets interesting. We’ve only started!
As the landscape dries out, and southwestern and southern plant communities mingle, traffic dies out even more than my cellular phone signal.
Drought-killed Juniperus ashei are joined with the first wild Chilopsis linearis. As seen below, even some straggly Fouquieria splendens and Parthenium incanum are at their likely tolerances of higher humidity and seasonality of rainfall. Zephyranthes drummondii are celebrating the previous week’s steam bath weather that reached a crescendo in needed, soaking thundershowers.
Diospyros texanum grow up high, while Platanus occidentalis grow low, abundantly reproducing.
These rugged, stunted Quercus fusiformis are showing signs of an increasingly dry climate, about 50 miles from their westernmost natural range in Texas, along Independence Creek. These oaks are near a riparian corridor, where the Dry Devil’s River joins with another drainage to become the Devil’s River.
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Turning south on SH-163, our elevation drops and with the Devil’s River nearby, the westernmost flora of the southeast and east appears, such as Carya illinoinensis and Platanus occidentalis.
More live oaks appear, too, and though the warm season is rather high in humidity, that’s enhanced by the river nearby. Notice all the ball moss on those trees?
I used the term “botanical tango” on an Instagram post for this stretch of road, along the Devil’s River. “Ecotone” or “transitional” isn’t unique to a few locales, but rather, many. Though this may be the only 4-way ecotone I know of.
The extents of all meet here: sub-humid Hill Country or eastern Edwards Plateau, semi-arid western Edwards Plateau, semi-arid Tamaulipan Shrubland or Brush Country of South Texas (yet often steamy from the strong Gulf influence), and the Chihuahuan Desert.
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Southwest Texas or Upper Rio Grande Plains –
SEMI-ARID SUBTROPICAL, Tamaulipan Shrubland, 1,200 ft elev, 18″ precip
Does anyone else see resemblances to areas near Carlsbad Caverns, South Texas, or Sonora here?
The last photos show a faint outline of low mountains above the horizon. Those are the Serranias del Burro, about 60 miles away in Mexico and the north end of the Sierra Madre Oriental. Accounts describe Hill Country plants such as Juniperus ashei, Quercus buckleyi, Platanus occidentalis, and Lupinus texensis. Even eastern vegetation remnants exist, including Cornus florida and Tilia americana.
Why? It’s where steamy Gulf air meets super-heated desert air from the Big Bend and Chihuahua. The mountains lift the moisture upward. A dryline often forms spring into summer from the eastern Big Bend up to southern Kansas; when it moves eastward, storms with rain develop.
Those storms and rain rarely form to the west, until the late summer monsoon season. This is also when high pressure to the east prevents rain yet allows humidity much of the summer. Rarely do those dryline-induced storms rain on the Texas side of the Rio Grande. When they do, places like Del Rio, Rocksprings, or Camp Wood are the main recipients.
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Lower Canyons, Eastern Big Bend –
ARID SUBTROPICAL, Coahuilan Desert (? – my name), 1,100 ft elev, 15″ precip
Crossing the Pecos River on US-90, the remote land is part South Texas acacias and Leucophyllum frutescens, and part Chihuahuan Agave lechuguilla. But few creosote bushes, let alone Chihuahuan hallmarks of saltbushes, bush muhleys, and so on. Climatology shows this is considerably more Gulf of Mexico-influenced than another 50 to 100 miles west, which is why this doesn’t fit into Chihuahuan Desert very well.
Langtry, Texas is a remote, small town nestled onto a bluff above the Rio Grande and the US-Mexico border, just west of the Pecos River confluence. It has a few saguaros planted in town, but it’s mostly a mix of the arid end of south Texas flora dotted by some Chihuahuan Desert flora. And limestone bedrock everywhere.
The expanses of Leucophyllum frutescens here with some Prosopis glandulosa are as simple as the Larrea tridentata expanses just to the west. One plant-savvy person I correspond with considers such Leucophyllum-dominated communities as Tamaulipan, not Chihuahuan.
Perhaps geographers in Mexico already named this as some Coahuilan Desert, or a dry Northern Tamaulipan subdivision of their thornscrub?
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Lower Canyons, Eastern Big Bend –
ARID WARM-TEMPERATE, Chihuahuan Desert, 2,000-4,800 ft elev, 12″ precip
And just like that, some distance west of Big Lozier Canyon and about half-way between Langtry and Dryden, Larrea tridentata suddenly dominates while Atriplex canescens and Muhlenbergia porteri begin to appear. Though Yucca torreyi extends over 100 miles south and east, it increases from here and points west.
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No surprise, I’m past sundown. We’re at 2,700 feet elevation in the “cactus capital of Texas”, where US-90 continues its climb to the high point of 4,700 feet in Marfa. In between, a power nap was had at the rest area near Alpine.
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Approaching midnight, I filled up with gas for the next 4 hours in the dark of night to get home. And nearing my home, after gassing up my car again, I would get 2 hours of sleep before returning to my then-day job.
That job in arid, warm-temperate Chihuahuan Desert: just a variation of the last 390 miles.
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Posts on gardens that May 2018 trip are here:
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The natural context of ecoregion and moisture from that May 2018 trip follow, including major changes along the route I drove to and from Austin.
MAP – EPA ecoregions w/ my refinements : : same map with my route
Ecoregions help plan gardens or tell the story of the land one is on. They consider many factors, that all meet to form a unique area including land vs. ocean influences, climate averages and extremes, soil types, and natural vegetation. (biomes and bioregions are similar but less thorough) My edits helped simplify the needlessly complicated mapping, and they add consistency where sloppiness confuses me and others I know. But I was limited by the detailed linework the mappers drew; I’ll have to finish my own maps some day.
- original source: https://www.epa.gov/eco-research/level-iii-and-iv-ecoregions-state
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MAP – average annual precipitation
Precipitation is averaged over 30 years and tells part of the story, though particularly central Texas and Austin that precipitation story is also the result of how it can vary enormously by year or even month – drought to deluge, then repeat. There is little change from the 30 years the above map used and the most recent 30 years, except slightly wetter recently.
- original source: https://prism.oregonstate.edu/normals/
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MAP – May dewpoint (large and close-up)
Dewpoint is the easiest and most useful way to show humidity, not “relative humidity” that varies relative to temperature. Surprise: a sizeable portion of Texas south and west of Austin to at least Del Rio is as humid during May as much greener Little Rock, Montgomery, or Myrtle Beach…yet much less rain falls. Austin is almost as humid as Savannah, Tallahassee, Mobile, or Hattiesburg.
Except in summer, the humidity or dewpoints between about I-35 and the eastern Big Bend in Texas vary by the week or even day, so there are dry days like where I am in the desert southwest alternating with humid days like the Gulf Coast. Too bad for them, humid days dominate by Memorial Day and can last into October.
Good thing on my several days in Austin and the trip, over half the time the drier air balanced out the humid air. Which has been the weather story every spring I’ve gone there. My entire drive home was in lower humidity, too.
- original source: https://prism.oregonstate.edu/normals/
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There are other factors, but the above maps summarize this trip well, more helpful than perceptions, rhetoric, or relativism. Plus, this is a blog post, not scientific volumes that are summarized into a quick phrase!
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I even have a music playlist for the trip – here
It's A Dry Heat 