The Grand Canyon

My first video post! Watch it in HD here: https://vimeo.com/88610713

Into the Trees

You know how when you're a kid you want to climb everything? Tables, curtains, trees, chicken coops, cars -- you name it. Well, that inclination never really left me, and in August 2012 I was able to satiate those childhood urges under the guise of "work!"

Leaving the Florida summer behind, I packed all my gear into Ruby (my "new" Ford Ranger) and headed west, making it out to Flagstaff, Arizona in three days.

With a camper on top, Ruby's better than any hotel

Sitting just under 7,000 feet, Flagstaff is an adventurer's dream town: an hour from the Grand Canyon, literally encircled by National Forest, only a few miles south of the San Francisco Peaks (Arizona's highest mountains), surrounded by some of the top rock climbing in the country and home to the best coffee shop the world has ever known, Macy's. As I was to be camping for the next three months, I first gathered some maps at the Coconino National Forest office and perused the real estate offerings -- I wanted to be close enough to town so commuting wouldn't be an issue, but far enough away that the Peaks were the only structures I could see on the skyline. After scouting out a few spots I headed just north of town, finding a gorgeous campsite at the base of the mountains.

 Home sweet home

Foraging Lepidopteran in a high meadow beneath the San Francisco Peaks

Though after getting to Flagstaff I realized I should have probably moved there long ago, what initially drew me to Arizona was the chance to work on a study concerning the invasion of an exotic tree pathogen into the American Southwest. Northern Arizona University (NAU) graduate student Betsy Goodrich and her advisor, Dr. Kristen Waring, are working with the native Southwestern White Pine (Pinus strobiformis) to proactively address threats brought about by the lethal white pine blister rust (WPBR), a fungal disease that has already caused significant stand mortality in the Pacific Northwest. Check out the video below, made at NAU and featuring Betsy and Kristen.



WPBR affects 5-needle pines (those which have 5 needles per fasicle, or "bundle"), including Eastern White Pine (Pinus strobus), western white pine (P. monticola) and southwestern white pine (P. strobiformis). Though its effects on high elevation ecosystems can be severe, from a purely biological perspective, it does have a fascinating life history, and the story of its spread in the U.S. is quite a tale.

 This juvenile Horny Toad (Phrynosoma spp.) wasn't too happy to get picked up,
but even that grumpy look can't hide the cuteness

Many thanks to Jim Worrall over at forestpathology.org for lots of the info in this post

In the mid-19th century, American land managers realized that the voracious wood consumption of the past 200 years was quickly depleting North American timber stands. This called for expansive replanting, but without many established nurseries in the New World, seed was instead shipped back to Europe, where the seedlings could be raised by knowledgeable silviculturalists in well-equipped nurseries. Once grown to an appropriate size for outplanting, the seedlings were shipped back to the U.S. Unfortunately, this transatlantic exchange opened up an avenue for Old World tree diseases to make their way to the New World, carried on American tree seedlings that had been infected while in European nurseries. WPBR was one such disease, first showing up on the East Coast in 1898, then on the West Coast in 1910, carried on White Pine seedlings grown in Germany and France. Though the disease spread along both coasts, it's been felt most strongly in the Pacific Northwest, where many stands of these ecologically and commercially important species have suffered extensive mortality. In 2009, WPBR was found in eastern Arizona, but Betsy and Kristen hope to get a head start on unraveling the mechanisms behind disease resistance before the fungus takes hold in the Southwest.

Mexican Campion (Silene laciniata)

But where it gets really interesting is when we look at how exactly this fungus (Cronartium ribicola) spreads. (If you'd rather not get bogged down in the details and vocabulary, skip this next bit). We start with the pine infection, which happens when one type of Cronartium spores, called basidiospores, enter pine needles through their stomata, establish a fungal infection and then grow down into the tree's bark. Eventually the infected area swells and becomes a discolored canker. In late summer, the fungus produces fruiting structures (analogous to the toadstools we're used to seeing on the forest floor) called spermogonia that produce another kind of spore called spermatia. These spermatia lie in a sweet drop of liquid that attracts insects, who then (unknowingly) carry the spores to other spermogonia, where they find their way onto receptive hyphae. The fusion of the spermatia and hyphae establish the dikaryon.

Next spring, other specialized reproductive structures, whitish-yellow blisters called aecia, appear where the spermogonia were the year before. Inside the aecia are masses of yet another kind of spore, aeciospores, whose abundance eventually pops the blister, releasing the aeciospores into the air. The aecia then break down, but the bark they colonized also dies. This annual spermogonia / aecia cycle is what eventually kills the tree as the fungus colonizes new bark, leaving "dead zones" in its wake.

But do these aeciospores go and infect other pines? No, that would be too simple! Instead, these spores (which can travel hundreds of kilometers) are only able to infect gooseberry (Ribes spp.), a relatively common forest shrub.

WPBR requires two hosts to complete its complex life cycle:
the eponymous pine, and Gooseberry (Ribes sp.), seen above

The aeciospores infect the new spring leaves of Ribes, and within two weeks the fungus is producing yet another kind of spore, urediniospores, housed in structures called uredinia on the underside of the Ribes leaves. These spores are released and reinfect Ribes, building up a large infection. Then in the fall, you guessed it -- another reproductive structure is produced, called a telium, full of teliospores. When weather conditions are right (cool and wet), these teliospores germinate and form basidia, which in turn produce lots of basidiospores. (Remember those? They're the first spore type I mentioned.) These disperse with the wind and, if they're lucky, come in contact with a white pine needle, where they enter through the stomata and start the whole process over again.

Scarlet Gilia (Ipomopsis aggregata)

Luckily my job did not in any way require a working knowledge of this complex life cycle. I just climbed trees! Well, mostly -- there was some community classification and environmental data to collect, but for the most part, we climbed. Our job took us all over eastern Arizona and western New Mexico to chase the elusive cone of the Southwestern White Pine. From the cones, Betsy could get seed, some of which went to seed banks, but most of which was to be used (as explained in the video above) to explore the spatial distribution and genetic basis of resistance to WPBR (as some pine individuals are more resistant to the disease than others). This knowledge could be invaluable in planning for effective forest management under the threat of a WPBR invasion in the Southwest.

 The Whitewater-Baldy Fire was the largest fire in New Mexico's history, burning more than 290,000 acres during the summer of 2012. This composite photo shows the aftermath just a few months later -- you can follow the blaze's path by the ashy brown and black, though a stand of unscathed aspens is turning gold on the far left. The fire consumed vast swaths of forest in the Gila Wilderness, including areas I had visited only a year earlier.

Our climbing team consisted of Chris, Shaughn and me, and after a couple days of training with Terry (US Forest Service), we were certified tree climbers! Don't get me wrong, I love vegetation surveys, but there's no field job like scaling a 90 foot pine and then getting to rappel down.

 Rappelling down an old Southwestern White Pine. We learned all matter of handy knots during this gig, from Blake's hitch to figure-8's to the ever-reliable anchor hitch.  

Shaughn (alimb) and Chris (aground) collecting in New Mexico

Going out for eight days at a time, we were able to see some of the best high elevation forest the Southwest has to offer. From Mount Graham in southeastern Arizona to the Gila Wilderness in New Mexico, each day brought new trees and each treetop provided fresh vistas -- a sunset from a pine crown is unlike any other.

What a climb. Can you spot Chris?

Chris admiring a beautiful (and low-hanging!) crop of cones

The only drawback to collecting pine cones is the sap...there is LOTS of sap. At the end of eight days I could barely separate the fingers on my hand -- seriously. And when you're covered in sticky sap, grime clings to you even more than it usually does in the woods. Needless to say, fall 2012 was definitely the dirtiest I have ever been. At the end of the first trip, Shaughn and I were legitimately concerned that we would not ever be able to get the dirt off of our arms. Proof of my concern? I bought a kitchen scouring pad to take in the shower.

Glistening with sap...but under those scales are precious seeds!

Hygiene logistics were made a bit difficult by the fact that Shaughn and I were living in the woods for three months, even on our off days, but we managed with the generosity of Betsy, Karen and Chris, who let us use their shower any time we needed. And man, never before had I felt the incredible luxury of having a shower. Living out of a tent is an easy way to learn just how little we really need to be content, and somehow, when you're in the woods, little chores that might seem a hindrance in residential life -- getting firewood, cooking dinner, fetching water -- are rewarding activities unto themselves.

Quinoa, a non-native species...best eat it before germination

I'll admit this looks like a diverse collection of slugs, but they're actually delicious mushrooms. Erik Nelson, an NAU mycologist, was kind enough to take Shaughn and me out on a foraging trip. Afterward, we feasted!

After climbing season ended in early October, I stayed on for a couple weeks to help harvest seeds from the cones. I told myself I would stay in Flag until my water bottle froze in my tent -- I made it through a few light snow showers before that happened, but the day before Halloween I packed up my truck, said goodbye to Betsy and crew, and headed back east. But not before paying a visit to our national treasure, the Grand Canyon, which we'll explore in the next post!

This OCD squirrel has neatly separated his cone stash: Douglas Fir (Pseudotsuga menziesii) in the background, White Fir (Abies concolor) in the front

Life in the Scrub

Click map above for enlarged image

I spent the first half of 2012 wandering Florida's Lake Wales Ridge, an elevated, sandy spine that runs for 115 miles through the center of the state. A million years ago when peninsular Florida was largely underwater, higher elevations on the Ridge resulted in a series of islands which, now landlocked, are home to a diverse and largely endemic flora and fauna. The fine beach and dune sands laid during the Pliocene underlie a number of distinctive upland habitats on the Ridge and give a desert-like appearance to parts of this strange ecoregion, whose initial harshness belies the beauty and wonder it contains. Exploring the ridge one will cross between these habitats quickly, walking through a field of Hypericum edisonianum in a dry seasonal pond, then fighting your way through a stand of saw palmetto in the mesic flatwoods, and if you brave the near-impenetrable oak thickets of scrubby flatwoods you just might emerge in the delightfully navigable rosemary scrub. Florida scrub is characterized by a paucity of large trees and a dominant shrub layer, with very hot temperatures, quick-draining sandy soils and low nutrient levels creating very trying conditions for any plant and animal life. But it is precisely because of these harsh living conditions that the scrub's flora and fauna have adapted in such fascinating ways.

Hypericum edisonianum, of the Saint John's Wort family, brings large patches of 

brilliant yellow to seasonal ponds at Archbold 

The Florida Scrub Jay (Aphelocoma coerulescens) atop Cari's head is the most famous scrub species, and not only because they're so gregarious. These birds are some of the few known cooperative breeders, with offspring remaining with their parents for several years to assist in raising siblings, watching for predators and defending territories. What makes Archbold jays so amazing is that the ABS Bird Lab has kept track of this population since 1969, and have data on every individual for the past 10 generations! Having such a complete dataset is enough to make any ecologist drool.

 These baby gators were hard to spot!

The Florida scrub is one of the most endangered ecosystems in the country, with urban development and agriculture encroaching on all sides. One of the largest undeveloped tracts on the Lake Wales Ridge is Archbold Biological Station (ABS), a 5,200-acre preserve which retains a variety of Ridge habitats in pristine condition. But ABS is much more than a preserve -- for over 70 years the station has been at the forefront of ecological research, most renowned for their long-term studies in population ecology, conservation biology and pyrogenic system dynamics. Seven research laboratories conduct a number of projects each year (with some data sets extending more than 30 years!) and are headed by top scientists in the field. One of the most phenomenal aspects of ABS is their long-running internship program, which gives aspiring young scientists a chance to work at a top field station while also conducting their own research project, which is a very rare form of employment! I was fortunate enough to have this opportunity, and in February I headed south to begin work in Archbold's Plant Ecology Lab.

The Plant Lab investigating Florida Rosemary (Ceratiola ericoides), adding to an extensive data set on this species' population dynamics going back to 1996. This data allows investigators to look at key demographic rates (survival, recruitment, etc.), analyze its response to fire regimes and climatic variables, and look at populations' spatial distribution.

 Calamintha asheii, a beautiful scrub mint

The ABS plant lab has more ongoing projects than I could list here, but some of the more prominent research areas include long-term demography of scrub endemics, population viability analyses, fire ecology and habitat restoration. From demography of an endangered scrub mint, to germination experiments, to scrub restoration and working to save what is likely the rarest plant in Florida (Ziziphus celata), my internship allowed me to participate in a range of ecological inquiry greater than that experienced by many in grad school! As in all ecology jobs, field work ran the spectrum of exciting to monotonous (counting hundreds of Lyonia stems certainly fell toward the latter), but all of the projects addressed interesting questions, stimulated discussion amongst labmates and made me think about environmental processes at multiple scales. Living and working at a field station like Archbold is a complete immersion in science, and being surrounded by so many brilliant people in such a unique ecosystem for six months was an invaluable period in my ecology career.

 

Florida Rosemary (Ceratiola ericoides) is a fascinating shrub. A dioecious species (plants are either male or female), it is killed by fire but recovers, steadily but slowly, from an established seed bank. In the photo at right, you see the charred "skeleton" of an adult rosemary in the background, and new recruits in the foreground. Because rosemary is allelopathic (producing compounds which inhibit the recruitment and growth of plants surrounding an individual), fires that kill large adult plants enable many endemic and endangered herbs to colonize these recently-cleared patches. As the rosemary population increases, these herbs persist in the gaps between the rosemary plants, but as these gaps close over time the optimal conditions for herb recruitment (low amounts of leaf litter and shrub competition) deteriorate. These gaps are opened again by fire, but wildfire suppression means that historic fire regimes are disrupted; prescribed burns are now necessary to perform this vital ecosystem process. 

Visitors learn about amphibians during the Save the Frogs Day event at ABS (in the background is Dr. Mark Deyrup, head of the Archbold Entomology Lab). Below, you can see one who entered a staring contest with an American Bullfrog (Rana catesbeiana). Two herpetology interns, Jeremy (above-right) and Cori, organized the event, which was a great success! Exposing kids to ecology and fascinating organismal biology at this age is of paramount importance to the conservation movement, and helps ensure an appreciation of the sciences in future generations.

 Watermelon polo at Lake Annie, a 90-acre paradise at the north end of the station.

 Tread-softly (Cnidoscolus stimulosus). Don't let the pretty flower fool you -- as its species epithet implies, the rest of the plant is covered in stinging hairs! Though "stimulating" isn't exactly the adjective I would use...perhaps "painful" or "expletive-inducing"...

A dragonfly larva emerging on Lake Annie 

Above, the larval form of the Echo Moth (Seirarctia echo), whose adult form can be seen below. Quite a striking transformation.

Rhexia mariana, often found in seasonal ponds on the station

A Strangalia strigosa exploring the bloom of a Prickly Pear (Opuntia humifusa). Though this cactus is always a major impediment during scrub travel, its large flowers put on quite a display and attract a host of insects. Opuntia flowers have remarkable thigmotactic (responsive to touch) outer stamens which curl inward when touched (see video below). Though this adaptation has not been thoroughly explained, it has been proposed that it protects the plant from pollen thieves (who don't actually pollinate) and helps to guide actual pollinators past the stigma toward the lower, inner anthers. These anthers hold ~80% of the bloom's pollen and are tightly shielded when the outer anthers curl inward in response to a visiting insect's (or prodding ecologist's) movement.

 A Southern Black Racer (Coluber constrictor priapus) resting in a Lyonia fruticosa

---

"The number of species thus far recorded on the Station’s main property includes 21 amphibians, 27 fishes, 44 mammals, 48 reptiles, 208 birds, 593 vascular plants, and more than 6,000 insects and other invertebrates, including the greatest diversity of ants (117 species) known from a single site in North America." -- www.archbold-station.org. Forty-three of these species are listed as endangered or threatened.

---

 A nighthawk nest is always a neat find in the scrub, though you're very likely to step on them before you see them! I only found these because I saw the mother bird fly off when I approached. Instead of building nests in shrubs, trees or other vegetation like many birds, the Common Nighthawk (Chordeiles minor) and its eggs rely on crypsis (camouflage) to avoid predation. Unfortunately I don't have a photo of the adult bird to show you, but suffice it to say that you could walk within three feet of them and not take notice. If you get close enough to startle the mother, however, she will often fly off awkwardly, feigning injury, to draw attention away from her eggs.

Tarflower (Bejaria racemosa) puts on a stunning display, its seven petals splayed outward as a bold invitation to pollinators. But don't try to nibble on the flower buds or steal nectar! As you can see in the photos at right and below, several insects have been trapped by the sticky substance that gives this plant its common name. Found only on the outside of the petals, this "glue" deters florivory and perhaps nectar robbing. Though this theory has yet to be tested, this entrapment might also attract spiders and other insect predators, giving the plant a few extra "bodyguards" to deter insect antagonists.

 An American Alligator (Alligator mississippiensis) in the Everglades, ~6.5 ft long

 The Lubber Grasshopper (Romalea guttata) is one of the largest and most distinctive grasshopper species in the U.S. This one is ~3 inches long, with what I think is an egg case on the tip of her abdomen.

 Central Florida has a surprisingly large black bear population, and though I never spotted one in the scrub, their tracks were excitingly frequent.

 This is a prime example of flatwoods, peninsular Florida's most widespread habitat. The understory is dominated by saw palmetto (Serenoa repens), with slash pines (Pinus elliottii) reigning as king (and lone citizen) of the canopy. In natural fire regimes, flatwoods will burn several times per decade; note the char marks on the pine in the photo.

 Robust Blue-eyed Grass (Sisyrinchium xerophyllum) is actually an Iris

Chapmannia floridana is a member of the pea family, whose standard petal color is yellow, as seen above-left. In the photo above-right you'll see a mutant Chapmannia with white petals, induced by changes in the genetic code that controls petal color in this individual's DNA. It is changes like these that drive the evolution of new floral morphs and, over time, species, as both the white mutants and yellow morphs are subjected to selection. An elementary example: Chapmannia is mainly pollinated by Bombus and Augochloropsis bees, who are especially attracted to yellow (and blue). Thus, the regular yellow morph serves Chapmannia well. But if we had an exotic pathogen reduce these bee species' populations, Chapmannia would likely see a consequent reduction in seed production due to decreased pollination. But if the white-petaled mutant successfully attracted an abundant moth pollinator (who are known to be partial to white flowers), we might see the mutant individuals begin to produce more seed than their yellow counterparts, with the mutant now receiving a relatively higher rate of pollination than the yellow morph. Over time, if ecological factors continue to favor the white mutant, we would theoretically see a greater number of white Chapmannias, and their mutualism with moths could result in reproductive isolation from the yellow Chapmannia, the evolution of morphological changes in floral structure to better suit their moth pollinators, and maybe even a new species! Of course, we're ignoring certain key questions like, "Could a moth successfully pollinate a Chapmannia in the first place?" and "Are the genetic changes that give the species white petals linked to any other deleterious traits?", but this simplified example illustrates one of the key mechanisms influencing the evolution of floral traits, pollinator mutualisms.

       Interns! Projects ranged from vegetation structure's influence on avian predation, to spatially explicit fire modeling, to grazing effects on endangered herbs, to anole intelligence, to how scrub jay kinship relates to territorial patterns, and more. Click here for more information about internships at Archbold. 

 In April, the largest delegation of Cuban scientists ever to visit the U.S. came to ABS for two weeks. Amongst other, more academic things, they taught us to salsa.

My independent research focused on the pollination ecology of Lyonia lucida, a common southeastern shrub in the blueberry family. Despite the large floral display of this species, pollinator visits have been noted as surprisingly rare -- actually, almost non-existent. My project investigated this mystery and tested for potential pollination by thrips, miniscule insects often found in flowers. Though I found thrips pollination to be unlikely, preliminary data suggest that we may just not be looking for pollinators during the right time -- there is a whole lot going on out in the scrub at night that we don't know about. I'll be returning to ABS this April to investigate this further; you're sure to see a blog post about it!

 A juvenile Gopher Tortoise (Gopherus polyphemus). Yes, that is a nickel beside him, and yes, it is the cutest thing you ever saw. (The first photo in this post is an adult tortoise.) Like many scrub species, these tortoises burrow to escape the summer heat, winter cold, predation and fire. These burrows can extend over 40 feet and may be over 10 feet below ground level. As you might guess, these large tunnels are important structures within this ecosystem and are known to be utilized by over 300 other species, including the threatened Eastern Indigo snake, gopher frogs, foxes, rabbits, and many more.

Well, it was hard to condense six months of life into one blog post, but then again, this post isn't all that condensed, is it? Thanks for reading; next we'll head to the Southwest and climb some trees!

Last Days in the Desert

Here is the (largely pictorial) summation of my last wanderings in the desert; please forgive my extreme procrastination.

 

Mexican Campion, Silene laciniata.  You can see a closely related
N.C. species (Silene virginica) in my July 2011 post about the Southern Appalachians.

Forefront: Century Plant,
Agave havardiana

 In mid-October Ben, Alex and I headed up out of the flat lands into the Chisos Mountains of Texas, the southernmost mountain range in the United States. Rising to over 7,500 feet, these mountains provide a a cooler, wetter, and generally more forgiving habitat in the middle of Big Bend National Park. Here you can find actual trees, including big-toothed maple, Ponderosa Pine, Douglas fir and Arizona cypress.

When we parked our truck in the Basin and began lacing up our boots, we got our first glimpse of the hike in. Though the green slopes called seductively with their promise of conifers and cooler temperatures, we knew that a 5 mile, nearly thousand meter elevation gain hike with 55 pound packs stood between us and our abode for the next three days, Boot Cabin. We trekked on.

Boot Cabin was a welcome sight, indeed. Not content to rest our legs for too long, however, we hiked further up Boot Canyon to do some spring scouting and take in the vista from the South Rim, which we had been told was the best view in the whole park.

The mountain shadows creep eastward, Abbey's "whiskey-colored light" fading slowly to pastels on the horizon, and the desert falls into dusk.

We sat down for a spell, while the swifts flew like bullets overhead, their aerial maneuvers almost too fast to see.  Green arteries flowed from the Chisos into the parched land below and from our giant's perch it seemed the ancient formations were but small piles of sand. As we marveled at the expanse before us, a lone Monarch butterfly made its way over the edge of the Rim and floated lazily south toward Mexico and a warm winter.

This Monarch Butterfly (Danaus plexippus) is headed south out of Big Bend, and can cover over 80 miles in a single day. The Monarch is known for its long yearly migration, over 1,000 miles from northern U.S. or Canada to Central Mexico for the winter. Most Monarchs live only 4 or 5 weeks, but as autumn approaches in the butterfly's northern home, a special generation is born which lives 7 to 8 months! These long-lived individuals make the southerly migration, winter over, then head back north. But these old timers don't make the full round trip -- several breeding rounds along the way split up the return journey amongst multiple generations.

Boot Cabin is maintained as a backcountry research cabin by the park. Outfitted with solar-powered lights and refrigerator, bunk beds and a fully equipped kitchen, we decided by the end of the trip that we could all make Boot Cabin our permanent home. (The damaged exterior in the picture at left? That's from bears trying to get inside.)

Alex strolling through a Chisos "prairie."

A mule deer spotted on the way to Cattail Spring.

---

In late October Alex and I headed to the Gila Wilderness in southwest New Mexico for a few days out of the desert. Hiking below golden, stretching aspens and seeing our breath in the mornings, it was hard to believe we hadn't even traveled over the state line. Our route, the Redstone-Baldy Loop, took us from low country along Whitewater Creek, all the way up to the highest peak in the Wilderness, Whitewater Baldy (10,895 ft.).

 It was as if someone had tipped a bucket of gold down the mountain.

Whitewater Baldy really isn't that bald, we discovered. Above is the view from the peak. I found that to really get the appropriate vista, you had to climb 30 feet up in a spruce tree...

 That's better.

 A Wild Geranium on the trail down to Whitewater Creek.

 Aspen trees (Populus tremuloides) are clonal organisms, propagating primarily through root sprouts rather than sexual reproduction. This leads to massive clonal colonies that are in fact a single organism, with the oldest known aspen colony currently celebrating its 80 thousandth (or so) birthday! That's right, the Pando Colony in Utah is both the oldest and heaviest known organism on Earth: over 6,000 tons and more than 80,000 years old.

---

Our second to last tour took us to Elephant Tusk, a remote section of Big Bend hosting a (supposed) menagerie of springs. Briskly flowing brooks were indeed a welcome prospect, but what was even more exciting for me was that we were mule packing! This time honored tradition is still alive and well in Big Bend, which employs its own full-time "mule skinner" (Joseph, seen above). The whole process -- from loading the mules on the trailer, to wrapping all our gear in large canvas tarps to hoist onto the mules' backs, to watching these hardworking beasts trot speedily ahead of us on the hike in -- was nothing short of fascinating. Able to carry 300 pounds apiece, the line of mules above carried 4 days worth of gear for 6 people a distance of 10 kilometers in about 2 hours.

Ocotillo (Fouquieria splendens) is another well-adapted desert plant very common in the Chihuahuan Desert. Most of its life is spent as a rather dead looking, spiny, leafless stalk (left) that can reach heights of 30 feet (more commonly 10-15 ft). But look closely and you'll see green stripes along the stalk -- these are active photosynthetic areas, allowing the plant to continue to produce sugars while leafless. Leaves (center) are produced quickly in response to rain, and are kept until drought conditions return, when these water-costly structures are dropped and the plant returns to its spiny, barren state. Brilliant orange-red tubular flowers (right) are produced at the tips of the stems sporadically throughout the year, with pollination services provided by hummingbirds and honeybees.

Big Bend Acanthus (Anisacanthus linearis), with its gracefully recurved petals,
is endemic to the Chihuahuan Desert.

I have no idea what caterpillar this is, but it sure is striking.

 Elephant Tusk (mountain on right) at sunset.

Finally, a Tarantula! I'd been waiting all fall to spot one of these beauties;
this one was relaxing on the rushes at my very last spring.

Resurrection Plant (Selaginella lepidophylla), is a Chihuahuan Desert native with an amazing tolerance for dry conditions. When water is scarce, this spikemoss curls up (as above) and enters a state of dormancy, tolerating moisture contents as low as 6% (most plants cannot handle below 75%). When it rains, Selaginella's cells rehydrate and its stems unfold in a flush of green (below). 
 

I hope you have enjoyed exploring the arid Southwest with me. The organisms inhabiting this harsh landscape exhibit some of the most remarkable adaptations seen in nature, and their environmental tolerances are a model for our own personal ones. If you'd like to read more about desert ecology, I highly recommend Desert Ecology by John B. Sowell.

I'm now working in the Plant Ecology Lab at Archbold Biological Station in Florida, so my next post will be from the Lake Wales Ridge.

Until then,

john