One of the numerous species and subspecies of Cristaria (family Malvaceae) blooms abundantly after winter rains soaked the Atacama Desert near Huasco, Chile.

In the deserts and semideserts of North America we have globe mallows, a prominent and showy wildflower group with members belonging primarily to the genus Sphaeralcea, of which there are several dozen mostly orange to apricot-colored species. The Latin name in fact is derived from the words for round (Sphaero) and hollyhock (Alcea) and refers to the tendency of the flowers to hold a cupped, rounded shape. In South America, there are ecologically analogous plants also of the Malvaceae which are lavender and belong mostly to the genus Cristaria, which has a similarly diverse array of species.

Taxonomy of this particular genus has not been done to any great extent to my knowledge, leaving the lines and divisions between various species somewhat indistinct.

Both of these mallow genera are easily recognized as a group, but they are considerably harder to parse out into actual individual species. It’s interesting to ponder how evolution has driven the development of these two related yet different genera on separate continents thousands of miles apart over millions of years. This mirroring pattern is seen elsewhere too, with a number of different species and genera within the same families occupying the same niches in both the Sonoran Desert and the Atacama Desert. Intriguing!

Numerous other wildflowers were also present after this wet winter and spring. The flowers of Cristaria tinted entire hillsides lavender in some places.

This particular rock outcrop was set in the midst of rugged mountains, whose bases were cloaked in sand dunes covered in millions of white Zephyra elegans bulbs, all in mass bloom. Down in the draw, however, the Cristaria were dominant.

Since these were mentioned and are worth a quick photo, this is a shot of the dunes covered in Zephyra elegans, a small bulb with sprays of white to very pale blue flowers standing about 12 inches/30 cm tall. In Spanish the name is Celestina, which might refer to the sky blue of the flower sprays? The draw in which the Cristaria that are the main subject of this post are growing slopes down to the left of the photo.

The Zephyra bulbs were by far the most dominant plants on these sand dunes skirting the bases of the coastal mountains only a couple of kilometers inland from the Pacific Ocean in northern Chile in October 2017. However an array of other species also grew mixed in, in lower numbers. I will make a separate post of the Zephyra bulbs at another point.

In places, the Cristaria mallows were the dominant flowers, tinting entire hillsides lavender with their shrubby, mounded growth forms.

The cacti mixed in with the mallows are a species of Eulychnia, possibly E. castanea.

A steep-sided canyon cuts down into the bedrock. Windblown sands cloak most of the nearby hills, driven by consistent westerly winds coming in off of the nearby Pacific Ocean.

A small livestock paddock outlined by rock walls lies in the distance, behind a floral display of lavender Cristaria and pale bluish-white Zephyra elegans.

As the road approaches the coast, drifts of fog emerge, floating gracefully over the dunes flanking the ocean. A variety of flowers comprised of at least a dozen species blankets the slopes.

While Cristaria is not quite as abundant on pure sand as on rockier sites, it is nonetheless a common component of the biological community here.

These coastal dunes in northern Chile are usually quite barren. Winters with decent rainfall tend to occur only once every 3 to 6 years, and average precipitation probably amounts to only about 3 inches / 75 mm per annum. But some winters exceed the norm and drop twice that amount or more, which results in mass blooms such as this one in October 2017.

A colorful combination of Cristaria, Zephyra, and reddish annual grasses crowd a sandy slope above a rocky canyon.

Zephyra elegans dominates the foreground of this composition. Most flowers are this delicate shade of palest blue, but ones that are pure white and sky blue do exist mixed into the population. They almost surely reflect UV light in a brilliant purple hue, which might not be visible to our eyes, but should be plenty visible to bees and other pollinating insects.

Cristaria also varies in color, with this individual being more on the purple side of lavender. The Eulychnia castanea cacti in the background are in flower and fruit.
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I will take a moment now to highlight the similarities of North American globe mallows (Sphaeralcea spp.) to the South American Cristaria plants that are the main focus of this post. As I said at the outset above, both genera are members of the Malvaceae, and both have about 20 or more different types spread out across the semiarid and arid regions of their respective continents. Both genera have several readily-distinguished species that grade confusingly into others that are less well-separated. Species vary along several gradients of plant shape, size, and structure, from small annual herbs to larger semi-woody perennials reaching over a meter tall. Leaf morphology varies significantly from narrow and divided to broad and lobed. And of course floral color can vary too, although lavender and orange are the dominant colors in each genus, respectively.

Let’s start with a closer-up view of an individual globe mallow growing amidst stands of cardon cactus (Pachycereus pringlei) including a fallen individual in Sonora, Mexico. This might well be Sphaeralcea coulteri, which is similar to and replaced by the more familiar-to-most-Americans S. ambigua farther north. Note the distinct congruities of both plant and habitat to the Chilean species of Cristaria just discussed….

Also similar is the color palette of associated species on these coastal sand flats in Sonora: Electric pink sand verbena (Abronia villosa) and white pincushion flowers (Chaenactis fremontii). It should be noted that while the colors are similar, the species are from different plant families than those discussed above.

The Sea of Cortez lies cerulean blue in the distance. These sandy flats are low and hot, quite a bit more so than the Atacama Desert, and rainfall is generally higher at an average of about 6 inches (150 mm) a year. But the increased heat means that evaporation is higher than in Chile, and therefore above-average rainfall is also required in winter in order to inspire these sorts of displays. A annual mix of globe mallows, sand verbenas, and pincushion flowers erupts from the sands after generous fall and winter rains in 2016 and 2017, leading to this March 2017 show.

 

One result of the higher annual rainfall in this part of the Sonoran Desert is that large cacti like the Pachycereus and several other columnar species are quite prevalent, along with many more species of small leguminous trees and other woody vegetation. Most of the Atacama Desert is so arid, and rain so suppressed by the cold Pacific and the Andes Mountains, that large perennials are much rarer and overall diversity of both cacti and other perennial plants including trees is lower there than here. One exception is bulbous flora, however – Chile has six to eight times more species of bulbs than northwestern Mexico does. Annual plant diversity might be somewhat comparable between the two deserts, although I admit this is an informal estimate.

Just as in Chile, a combination of sandy dunes and flats are separated by rugged mountain ranges along the Sonoran coastline. Orange Sphaeralcea coulteri bloom en masse on the sandier areas.

A lobe of the Pacific Ocean separated from the main body of water by the 800 mile-long Baja California Peninsula, the Sea of Cortez is significantly warmer than the Pacific Ocean is. Fog is rare in this part of the Sonoran Desert, unlike on the Pacific Coast across the peninsula, which lies only about 150 miles (~200 km) west of here. Otherwise, the habitat is somewhat similar in many important regards to that of the Atacama Desert in Chile. (The actual Pacific shore is very similar, in fact.)

Sand dunes flank the Sea of Cortez in central Sonora, Mexico in March 2017.

The Sea of Cortez is often fairly placid since it is insulated from oceanic swells created thousands of miles away by the land mass of the Baja Peninsula west of here. Of course local and regional weather forces can make large waves when the timing is right, but in the absence of that, the sea’s surface regularly is very calm, and sometimes even glassy.

Close-up of pink sand verbena, white pincushion flowers, and orange globe mallows on the sand dunes.

A blue sand lily (Triteleiopsis palmeri) blooms on sand along with the other plants. Check out my other post of this species for more information on these beautiful bulbs.

Teddybear chollas (Cylindropuntia bigelovii) also grow well on stabilized sand dunes. Giant cardons (Pachycereus pringlei) reach some immense sizes here as well.

Cardons are the largest cactus species on earth on average, with many individuals reaching 50 feet tall (15 meters) and weighing ten or more tons. They do well in sandy sites because of the ability of sand to absorb and retain water, and because they develop such massive root structures that they can support themselves in a way that the more familiar saguaro cactus (Carnegiea gigantea) cannot do quite so well in loose substrates.

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Moving northwards, we can observe the ecosystemic functions of Sphaeralcea species in different climates yet again. Because I live in North America, it is easier for me to have observed and photographed different species of orange globe mallows in various habitats than to have done the same with the lavender ones on just one 12-day trip to Chile. A Wikipedia article on the genus Sphaeralcea indicates that there are between 40 and 60 different species in the genus, depending upon the authority and the criteria used to separate them. Some are in fact quite rare and narrowly endemic to localized places, while others are widespread and common and can reach mass abundances covering thousands of acres in good bloom years. What follows next are some photos of Sphaeralcea munroana (Munro’s globe mallow) in northern Arizona.

This extensive and dense patch of Munro’s globe mallow covered the side of a mountain in a part of my state called the Arizona Strip. South of the Utah state line and north of the Grand Canyon, the Arizona Strip is a vast, isolated, and nearly unpopulated stretch of rugged plateau and canyon country lying on average around a mile above sea level. This particular patch of S. munroana is extra showy thanks to the presence of a burn scar from about 8 to 10 years before this photo was taken in May 2014.

Due to time limitations and steep terrain limiting my ability to go hike there, I was unable to go photograph the thick stand of orange globe mallows in the first photo of the series. But I was able to easily visit other patches of S. munroana right off of the gravel road I was traveling, such as this one, also located on a burn scar, probably from the same wildfire complex.

Sphaeralcea munroana is known for its ability to thrive and rapidly spread in the years following a major ecological disturbance such as a wildfire. The set of photos below are from May 2009, four years after the devastating Mojave Desert wildfires of May and June 2005. Fueled by invasive weeds, primarily cheat grasses (Bromus rubrum and B. tectorum) and Mediterranean grasses (Schismus barbatus and S. arabicus) that grew abundantly after the record-wet winter of 2004-2005 and then dried out in early summer heat, these unnatural desert wildfires were devastating to hundreds of thousands of acres of Joshua tree woodland and pinon-juniper forest in Arizona, California, Nevada, and Utah. They were and still are the worst desert wildfires ever seen – normally deserts are too dry and sparse in fuel to burn, so it was a highly unnatural occurrence with severe consequences for the Mojave Desert ecosystem, especially some of its most biologically diverse portions.

The ruinous ecological consequences of these unprecedented desert wildfires in ecosystems not adapted to withstand them or recover from them will be the subject of another post someday. But for the purposes of this discussion, suffice it to say that the globe mallows were not only not negatively impacted by the fires, but were in fact very favored by them since competing vegetation was cleared. The four photos above were saved from the Desert USA Wildflower Report website on May 8, 2009 after a visitor to the region took photos the week beforehand. Evidently the region in question is the Sawmill Road area of the Mormon Mountains in Lincoln County, Nevada, which lies northwest of the town of Mesquite, NV; west of St George, UT; and northeast of Las Vegas. While the photos are of a rather beautiful color field, the sad and burnt Joshua tree corpses (Yucca brevifolia ssp jaegeriana) are gone forever, never to return. I visited this region in winter 2017, and hate to report that 12 years later there is no sign of Joshua tree regeneration. They cannot recover from wildfires and their local extinction is more or less permanent.  🙁

Opuntia erinacea flowers on the slope alongside the globe mallows.

Anyway, back to the Arizona Strip photos, here the globe mallows thrive on a burned slope, possibly also from 2005, and almost certainly from somewhere between 2000 and 2007, when invasive and weedy grass-fueled wildfires were a nearly annual occurrence in the region.  Nearby, a grizzly bear prickly pear cactus (Opuntia erinacea) hefts forth a bright magenta bloom. While overly-frequent grass-carried wildfires would be harmful to this region too, the local pinon-juniper woodland is an inherently more fire-adapted community than the deserts at lower elevations nearby are. Most plants here have fire adaptations that enable eventual recovery, such as seeds that germinate post-burning or the ability to resprout from crowns at the soil surface.

Banana yucca (Yucca baccata) is capable of crown-sprouting and will recover from the loss of its top growth in a wildfire. This individual might well have been burned about 7 to 12 years before, but has regrown large enough to be able to bloom again. Dead juniper tree skeletons stand in the background indicating the age of the burn, which didn’t kill every tree on this slope, either.

A hedgehog cactus (Echinocereus engelmannii) flowers on the same slope as the yucca and prickly pear. It probably escaped the flames altogether because as a rule cacti are fire-intolerant and most will die after their spines are burned off.

Lastly for the USA section of this blog post, let’s go visit the Navajo Nation near Shiprock, New Mexico. I took a tour through this region in late May 2015, and was extremely surprised to see the extent of flowering of several species I did not know grew in this high-desert region of the Four Corners.

Three of the primary mass-blooming wildflowers were the orange Sphaeralcea coccinea and S. parvifolia (of course!), purple scorpion weed (Phacelia crenulata ssp corrugata), and white Esteve’s pincushion flower (Chaenactis stevioides). I was dumbfounded to learn that not only did these three species all survive here, but that they were capable of as much of a dramatic bloom on the Colorado Plateau sands at 6000 feet elevation, as in the vastly more famous Lower Sonoran Desert is. This was very much news to me!

The Navajo Nation is private land and we were not free to wander at will, so I took the photos from the road easement, looking towards the homes of Navajo Tribal members who are fortunate enough to call such a scenic place home.

Long-distance telephoto zoom shot across the unexpected wildflower fields here in the heart of the Colorado Plateau country. I thought that these were mainly lower-desert species before now.

You learn something new every day!
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Now that we have visited both North and South America to compare the similarities between these two different genera of mallows, let’s go back to Chile for a few parting shots of Cristaria in additional spots.

A different day brings a different scene. Near the entrance to Llanos de Challe National Park, a showy field of variously-colored wildflowers runs on the narrow coastal bench between the ocean and the steep coastal mountain ranges.

Cristaria joins stands of hot pink Cistanthe and lurid orange Argylia radiata for a unique and vibrant display of color.

The bright pink of Cistanthe intermingles with the lavender Cristaria. While the flowers are superficially similar in that each species has five petals in a radial arrangement, they are in different botanical families. Plant families are usually determined along floral architecture, and the two families differ significantly in ways that might not be obvious to non-botanists. As mentioned before, Cristaria is in the mallow family (Malvaceae) while Cistanthe occupies the moss rose family (Portulacaceae).

A vibrant show of Chilean wildflowers graces the Atacama Desert for a few short weeks in a good spring. It may well be years before this display repeats. Only mother nature can determine when and where good shows will occur. But we humans can certainly appreciate, and preserve, such events by taking care to not use off-road vehicles on the sand dunes that support many of the most impressive displays.

I hope readers enjoyed this visual tour of the analogous globe mallow species growing between two different deserts on continents 5000 miles apart!