Distillations magazine

Unexpected Stories from Science’s Past
May 16, 2024 Environment

Everyday Monsoons

Washes and other gaps in the Sonoran Desert.

Color illustration of a desert scene with a car in the foreground and storm clouds on the horizon
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Illustrations by Sarah Kaizar

When we exited Circuit City, we entered a different climate than the one we had left an hour earlier. My sister doesn’t recall why we were in the last Circuit City in Tucson, Arizona. Neither does my dad.

We mostly remember the 40-degree dive in temperature that afternoon—from around 110 to 70 degrees—and how eerie it felt. It looked and sounded eerie, too. There’s no forgetting those charcoal-colored clouds that swelled and snarled in the sky until they became the sky. The kind of noisy clouds that produce enough intracloud and spider lightning to muffle distinct bellows of thunder into a steady grumble. Growling clouds whose gruff chatter sends the most unambiguous message: go home if you can.

We hardly reached the car before the sky cracked. During rainy car rides, we, like most children, enjoyed watching raindrops merge, split, and inch across the backseat windows. Not this ride. Monsoon raindrops did not offer the same cute and animated experience. These drops fell from the sky like they had something to prove.

It must have been late July or early August, the Sonoran Desert at its hottest, the rising heat drawing massive thunderstorms from the east. After a long journey in water-saturated air masses that formed over the Gulf of Mexico, these raindrops plunged 2,500 feet at 20 miles per hour before bursting into white water against cars and concrete. Literal tons of monsoon rain pounded on impermeable desert hardpan and ran off into one-shot streams that added division to the long-standing watershed. Only when these heavy raindrops reached the soft, contoured desert sand in mass did they gain momentum and form flashes of a river that coursed through the landscape until it became the landscape.

Monsoon rivers in the Sonoran Desert might last only three hours. But that’s enough time to deposit concentrations of moisture and nutrients in dry floodplains called desert washes. In harsh, semiarid regions, annual monsoons inform where, how, and when most life, struggle, and biodiversity occur. A friend from Mumbai calls Tucson thunderstorms “discount monsoons.” But, by creating washes, these sporadic and isolated rains arguably do in hours what monsoons in India do in a season: shape land, ecology, culture, and power.

Most Tucsonans refer to any cacti-filled scrubland between properties as “the wash.” However, to the Tohono O’odham, the ak cin is more precisely the “mouth of the wash.” Ak cin farmers know the mouth of the wash as small, seasonal floodplains that “harvest and concentrate water, nutrients, and seeds from watersheds to support greater densities of life.” In the regions northwest and southwest of Tucson, Tohono O’odham, Pima, and Hopi communities practice what their ancestors perfected over 3,500 years ago: planting desert cotton (Gossypium thurberi) in irrigated desert washes.

Color illustration of a trench in a desert landscape

Ecologically speaking, the desert wash is a dry riparian habitat—a hardy community set on the shores of a temporary river. Heraclitus believed a person can’t step in the same river twice—but how did he define river? He believed a river is not one thing but a collection of parts in movement together. To Heraclitus, you step in a moving river once because your next step is in another constellation of different moving parts that merely resembles the same river.

Would Heraclitus imagine a desert wash as a river you can step in twice? A desert wash does not move or change dramatically. Its sandy, gravelly parts do not shift quickly with each step. But neither is a desert wash one unvarying thing, static nor singular. It’s the living afterlife of—or, maybe, the second step into—an everyday monsoon. And its thingness embodies a confluence of quotidian, occasional, and infrequent tensions akin to what Christina Sharpe describes as life in the wake of slavery. A living landscape that holds onto a few days of torrential rain is deeply uneven.

Few things concentrate wealth and resources like desert washes. As ribbons of relatively moist microhabitat, this terrain occupies tiny percentages of the desert landscape but significantly influences how life takes place in the greater watershed. It’s a place that divides haves and haves-not with granular clarity.

Why did settlers see the desert and envision a controllable oasis for colonialism to grow? What did settlers misread or fail to see?

In the wash of monsoons—and the struggle of species to survive there—we see the effects of concentrated wealth and resources in increasingly warmer and drier environments and how different species of plants and animals evolve to thrive in these gaps in land and rainy seasons. We can question how humans have embraced desert washes to reinforce violence against plants, people, and places. And we wonder why white settlers imagined using black labor and foreign seeds to establish cotton plantations in Arizona where generations of ak cin farmers irrigated wild cotton in desert washes. Scientists and scholars are still learning what the ak cin farmers always knew: so much life—biology, biodiversity, and biography—emerges from holding onto what you can.

Color illustration of a prickly pear cactus in bloom with a deflated soccer ball

Cactaceae and Fabaceae: Gaps in the Land

We moved to Tucson in 2002, the driest year the Sonoran Desert had seen in 1,500 years. It was our eighth move in 10 years, and 10-year-old me was ready for comfort and consistency. Surely the cacti, legumes, and mallows in the wash behind my new home were also waiting for comfort and consistency. Since the mid-1990s, drought had been the desert’s only constant. This struggle was unknown to me and my sister when we walked into the wash for the first time. It was January, and desert life was preparing for the relief of low-intensity rains that would not come.

Our first steps into the wash were loud; dried plants and plant parts crumbled noisily underneath us. It was too early for owl hoots. There were no scurrying western whiptails or desert spiny lizards or kangaroo rats. We alone broke the silence and stillness of the wash. Hawks glided over the wash without bothering to look down. We carefully crunched downhill, dodging cacti, brush, and rocks as we made our way toward the ephemeral waterway 30 to 40 meters below.

Color illustration of a bird peeking its head out of a hole in a cactus

The first part of what Tucsonans call the wash is where shrubs remain shrubs and soccer balls die but have afterlives. Columnar cacti, such as barrel cactus and saguaros, flourish in this exceptionally arid, upland terrain.

If the Americas are the land of cacti—home to 1,799 of the world’s 1,800 cacti species—then the Sonoran Desert is the land of the big-game cacti. These giant succulents are only native to the U.S.-Mexico border states. But ask the Tohono O’odham about saguaros, and they might tell you they grow only where their ancestors lived because each columnar represents a human spirit. Follow a gilded flicker or elf owl, and you might also notice a saguaro providing shelter for other species and their kin.

Prickly pear (Opuntia) seems like the most abundant cactus family on these slopes, followed by jumping cholla (Cylindropuntia fulgida) and the two columnars: barrel cacti (Echinocactus and Ferocactus) and saguaro (Carnegiea gigantea). Look closely, and you’ll also see a few deflated, sun-cracked soccer balls haunting the slopes, too misshapen and hardened to roll down the hill.

Many species can pop a soccer ball in this land of sharp and pointy plants. Spines do more ball-busting than thorns and prickles, but not all spines destroy equally. Your ball might survive an encounter with a prickly pear or jumping cholla. These flimsy plants just don’t offer enough resistance. Hit a prickly pear and its pads, or nopales, tend to crack and split under pressure. However, land in a patch of pears and you won’t be able to reach your ball. Once trapped and desiccated, these balls can shelter small rodents, reptiles, and birds seeking refuge from the sun and predators. But these microclimates are often fleeting since so many cactus-eating animals, such as javelina, tortoises, and deer, graze on pears and chollas at the height of arid winter, when the nopales ripen most.

Most balls meet their match hitting saguaros or barrel cacti. These giants don’t budge. Younger saguaros are worse than older ones because they have longer and sturdier spines. The giants turn gentler with age, their uppermost spines growing thinner and more needlelike, while a woody, barklike exterior replaces the lowermost spines. Saguaros develop spines for various reasons that have nothing to do with errant soccer strikes. Their spines are leaves that have evolved to provide shade, collect sparse amounts of dew, and protect the water-laden stems from predators. The fishhook barrel cactus (Ferocactus wislizeni) literally catches balls out of the air like a goalkeeper. The plant’s spines are so effective that Mohave people used them to fish.

Color illustration of a saguaro cactus with blooms, a bird flying in the background

Nearing the bottom of the basin, the uphill vegetation gives way to a more distinct and dense desert wash ecosystem. The term shrub is relative and deeply connected to place and resource access. Lower down, there’s too much water for columnar cacti to flourish, but the deeper soils and nutrients are enough to help shrubs such as Acacia constricta and Acacia greggii grow into full-blown desert trees. Like most tree shrubs lining the corridor, Acacia are leguminous plants that are champions of drought tolerance and make the whole watershed more livable.

After columnar cacti, woody legumes are this desert’s second most common feature. A desert wash would not resemble much of a habitat without rows of mesquite (Prosopis) and desert ironwood (Olneya tesota) lining the dry riverbanks. The legume family (Fabaceae) is found in all world habitats but holds critical niches in arid desert climates where decomposition of organic material is slow and low amounts of nitrogen in the soil limit plant growth and diversity. More than 280 species of leguminous plants grow in the Sonoran Desert, making up about 11% of all native species. These plants serve as the lifeblood of the local nitrogen cycle because many harbor colonies of nitrogen-fixing bacteria (Cyanobacteria) in their roots.

Flooding events may drive nitrogen from the surrounding desert into the wash, but during interflood periods, nitrogen-fixing legumes along desert streams are the primary supplier. Without this additional infusion, chlorophyll molecules cannot efficiently capture sunlight energy in photosynthesis, resulting in smaller and weaker leaves, fragile stems, and bitter fruits.

Legumes do not hold onto everyday monsoons without help. Scientists are still determining how, but they are confident that the multispecies exchanges between legumes and bacteria produce enough nutrients to feed the wider desert wash ecosystem. Some scientists even believe this relationship helps the sediments beneath the stream hold greater amounts of water.

Chemistry helps transform atmospheric nitrogen into leguminous proteins for animals. Starting in monsoon clouds, lightning-charged nitrogen in the atmosphere combines with raindrops and falls to the ground. Soil bacteria then turn that nitrogen into bioavailable compounds that plants can absorb and store in nitrogen-dense tissues, especially peas or bean pods.

Color illustration of legume pods hanging from branches

According to one source, the Tohono O’odham once called themselves the Babavi O’odham, or the Tepary Bean People, and were known to harvest beans from wild teparies (Phaseolus) in desert washes. Numerous other animals, including deer, rabbits, squirrels, and coyotes, feed on these sugary and protein-rich seeds. The caloric and nutritional value of bean pods in desert-wash ecologies cannot be overstated, especially in the prolonged lull of drought.

When Tohono O’odham crops failed, mesquite and saguaro plants were the most abundant and accessible foods. Mesquite is best harvested before the rains and can provide flour year-round. The Pipa Aha Macav, or Mohave, eat mesquite pods to “alleviate starvation during seasons of low or no flooding.” Desert ironwood seeds, which ripen and fall from May to July, provide Tohono O’odham with an essential source of protein before the monsoon.

As my sister and I first approached the wash that dry January morning, we did not know how eagerly the drought-stressed animals would have welcomed a ripening mesquite or ironwood pod. However, any such blessing was still a short winter and a long spring away.

There’s a politics to looking down when you walk, a feeling of humility mixed with respect and some precaution. It’s about knowing your place. There are also too many venomous snakes in Arizona for reverie. All 36 known species of rattlesnakes are native to the Americas, and one-third of these so-called “New World vipers” are native to Arizona. Snakes are widespread in desert washes, where the nitrogen cycle and food chain overlap, drawn to the density of life. As we walked through the leguminous tree break and into the wash, we remembered to watch for snakes; we were too new to the desert to know that it wasn’t rattlesnake season. That morning they might have hibernated in groups, sheltered in burrows as we passed unaware.

Still, practice makes perfect, and as Richard Pryor suggested years ago: black people don’t get bit by snakes. We’re too smooth, our shoes are too clean, and white supremacy has conditioned us to look down when we walk. Between the region’s uneven landscapes, snakes, and settler colonialism, Arizona has given people of color—black, Indigenous, and Mexican—few reasons to look up when we walk. Nevertheless, we did.

Color illustration of a child's legs walking with a snake in its path

Malvaceae: Gaps in Society

We don’t remember seeing desert cotton in the wash that January morning in 2002. It certainly wasn’t in bloom. We only recall how cotton shaped our socialization into Arizona’s public schools. Every spring, fifth graders at Manzanita Elementary School participated in Civil War reenactments that felt like one part school play, one part Renaissance fair, and all parts unnecessary. A paid crew of actors came to the school to set up various scenes and provide students with costumes and props.

These are childhood moments that one hopes to forget. But there’s no forgetting the scene of slavery and the one prop they didn’t need to bring: unseeded cotton bolls that likely came from one of the state’s 238,000 acres of planted cotton that year. As the only black person in the reenactment, there was nowhere to look in the room but down. The reenactors handed every student (thank goodness) a bundle of stems, each carrying a few bolls of cotton to deseed. We hung our heads down and picked the seeds out of the cotton.

My sister was forced to repeat this experience four years later, a terrible reminder of the forces that have historically introduced many black people to the desert now called Arizona.

Before Arizona became U.S. cotton territory in 1848 and then a cotton state in 1912, it was a cotton region for millennia. Cotton has likely grown in the land longer than saguaros, which emerged only 13,000 years ago. Fast-forward to the antebellum United States: cotton and racism helped white settlers imagine life in the desert. Southern planters pictured transplanting slavery and cotton plantations to newly acquired territories from the war against Mexico (1846–1848). They quickly learned that Indigenous nations had been irrigating cotton in desert washes and at a large scale for generations.

Color illustration of an ironwood branch in bloom

Desert cotton, or algodoncillo in Spanish, is native to the Sonoran Desert. It is a member of the mallow family (Malvaceae), like hibiscus, okra, and cacao. Its close cousin, Gossypium hirsutum, accounts for 90% of today’s cotton. Like Cactaceaeand Fabaceae, mallows do well in arid climates. Similar to aloe vera and cacti, mallows contain slimy mucus in their tissues, which helps them manage and preserve water in dry regions. Most desert mallows are edible but are seldom eaten because of their gumminess. Pima, or Akimel O’odham (River People), only harvest white mallow (Eremalche exilis) in the late winter and spring as a famine food. Of 4,225 known species, cotton is the only Malvaceae with poisonous properties. But trade in inedible cotton products has long been a way for Indigenous peoples to feed themselves.

No one harvested desert cotton better than Hohokam farmers. After migrating from northern Mexico around 300 BCE, the Hohokam people built small dams and canals to irrigate cotton and other crops in the Salt and Lower Verde river valleys. The Hohokam eventually developed a massive canal system that spread cotton culture and products across the region from 800 to 1400 CE. Pima and Tohono O’odham became the heirs of the Hohokam cotton culture in the Gila River Valley. That river ran dry for the first time in human memory just 12 years after the U.S. Congress forced the Pima, Maricopa, and Tohono O’odham to live on the Gila River Reservation in 1859.

Pima oral history remembers the period from 1871 to 1911 as “forty years of famine.” During this period of Arizona state formation, settlers violently replaced Indigenous desert-cotton growers with foreign cotton varieties and migrant laborers. U.S. military battalions came to the Arizona territory to wage war against Native populations. Settlers flooded the Pima cotton markets with foreign cotton products. With domestic markets choked out, Pima shifted to growing wheat and alfalfa, feeding the U.S. cavalry fighting “Indian wars.” The U.S. government developed the Pima Indian School into a farm that exploited Pima’s knowledge of desert rivers to grow alfalfa for horse feed. In order for Pima to supply the military with millions of pounds of wheat in the 1860s, the army began to divert water from the Salt and Gila rivers to irrigate fields.

The Desert Land Act of 1877, which formally endorsed economic development in arid and semiarid lands in territories such as Arizona, changed the landscape like a monsoon. The act effectively ended the appropriation of ancient Hohokam irrigation canals by establishing modern ones. By the 1890s, the Pima had lost more than 70% of Gila River water due to upstream diversions. Mormons arrived in the Sonoran Desert on an expressed “cotton mission.” Then the transcontinental railroad offered cash prizes to the best cotton-growing settlers along the rail connecting Tucson, Phoenix, and Los Angeles.

Time soon revealed that the profitable cotton growers combined Indigenous labor and Egyptian cotton. Scholar Jennifer Bess tells how the Bureau of Indian Affairs and Bureau of Plant Industry cooperated to transform 55 acres of the Gila River Reservation into a demonstration farm to experiment with Pima-Egyptian cotton hybrids. This joint effort helped isolate the first American-Egyptian variety in 1910: Yuma cotton.

The following year was the 40th year of famine, and, as if to celebrate, cotton growers formed the Salt River Valley Egyptian-Cotton Growers Association and completed Roosevelt Dam. With these figurative prerequisites for statehood met, Arizona became the last state of the continental United States in 1912. Settlers-turned-Arizonians dubbed their state the New Egypt.

Color illustration of a map showing natural waterways and canals

White settler colonial imaginations for the lands they occupied were vaster in breadth than in depth. Even though the Sonoran Desert experienced more rainfall between 1905 and 1917 than it had in 1,200 years, settlers could see only a marginal region where, in their minds, plants and animals from deserts flourished best. European imperialism in Africa fed this narrow vision by selling African products for American deserts. Arizona farmers not only obsessed over integrating cotton hybrids from British Egypt; they also imported date palms from French Morocco and ostriches from British South Africa.

With the help of the USDA, settlers also introduced numerous plants from Asia and the Americas to Sonoran Desert soils to see what would thrive. These were curious times, full of uncertainty and tons of questions. Would orange trees from southern China grow well south of Phoenix? How about Mexican pecan trees in valleys north of Tucson?

Everything was up for debate but the racist division of labor. Arizona farmers came to the desert expecting to exploit Indigenous, black, and Mexican workers. According to Walter Swingle, an official at the Gila River Reservation demonstration farm and importer of date palms, “older Indians all remember when cotton was grown by their people, so it is not a new thing.”

Cotton helped inform the one-dimensional, or monocultural, way settlers valued farmers of color as simultaneously indispensable and disposable. Settlers exploited the Pima and Tohono O’odham desires to return to their ancestral practices of planting cotton seasonally. Even before the cotton boom of World War I, 5,000 to 7,000 seasonal Indigenous farmers helped make possible the industrial transition spurred by the war. State officials also sanctioned a 2,600-acre cotton plantation on the Gila River Reservation.

With war increasing demand for cotton worldwide, the USDA encouraged Goodyear Tire and Rubber Company to invest in the Pima-Egyptian cotton cultivar (Gossypium barbadense) in 1916. Within a year, Goodyear became Arizona’s top cotton producer. Goodyear and other Egyptian cotton growers placed advertisements for cotton pickers in 20 newspapers in the U.S. South and Midwest to plant and harvest tens of thousands of acres. The goal was to convince black farmers they were most valuable as cotton pickers—and that Arizona was the place to pick cotton.

After only growing by 800 people since 1890, Arizona’s black population exploded—from 2,009 in 1910, to 8,009 in 1920. Arizona’s cotton growers association then began soliciting labor from Mexico to work in the border town Nogales. It eventually transported nearly 35,000 workers from Mexico between 1918 and 1920 on roads likely built by Mexicans.

Cotton’s relationship with settler colonialism, rather than the plant’s natural toxicity, threatened the health of migrant and marginalized laborers. Arizona was home to the largest arsenic producer in the country, American Smelting and Refining Company, and the USDA invested heavily in promoting the company’s products as insecticides for cotton crops, which poisoned seasonal laborers in Arizona’s wartime cotton industry. As if white toxicity and agrochemical poisons weren’t harmful enough, the constant fear of venomous rattlesnakes while harvesting cotton kept black folks looking down. But snake bites and agrochemicals would not be their only concerns.

Once demand decreased with the end of World War I, migrant workers realized how expendable the cotton industry and its culture saw non-white laborers. Arizona officials wasted no time deporting Mexicans back to Mexico and Pima and Tohono O’odham back to reservations.

Color illustration of a cotton branch

Arizona public schools seldom teach what happened to black workers. The re-enactors who came to my fifth-grade class failed to mention that black cotton growers built homes in communities that helped lay the foundation for Phoenix and other cities in the state. Our teachers surely did not highlight the black doctors, engineers, and entrepreneurs who built hospitals, roads, and businesses.

Instead, we learned that Arizona’s second cotton boom in the 1930s was expressly white. Books and street names reminded us that Arizona politicians encouraged white Oklahoma farmers to come west to Phoenix to grow cotton during the Dust Bowl. Ignored was the fact that the Ku Klux Klan formally organized in Phoenix the year after the city’s black community established the westernmost NAACP chapter in 1919. It was more settler nonsense to skip over the 1921 federal investigation of the Klan in Arizona, which showed that for years the organization had infiltrated every sector of government, from the mayoral offices of Phoenix and Tempe, to the sheriff’s department, to the county’s judicial benches.

The black teacher my sister and I never had in Arizona might have suggested that even though the cotton industry engineered the cotton plant to remove its poisonous gossypol pigment, the industry did nothing to protect its black laborers and their communities from noxious whiteness. “Imagine this,” the teacher might have said somberly. “When the Klan started to openly march the streets of Phoenix regularly, they did so with an unambiguous message for black folks: ‘go home if you can.’ ”

But go home where?

Monsoons tear through the desert yearly as domineering hydrological disturbances that shape the landscape’s structure and function. For nearly 200 years, settler colonialism has worked to harness monsoons and other water in Arizona, sustaining cotton and whiteness with one flood and washing away marginalized farmers and their impact with the next.

But those farmers are more like legumes than cotton. Even in the harshest conditions, on the edges of the desert wash, they create their own conditions for survival.

Color illustration of a cotton field

Strange Strangers: Gaps in Knowledge

The Santa Cruz River no longer runs in the San Xavier District of the Tohono O’odham. But if you drive northwest from Tucson to Phoenix, you’ll see ostrich farms, pecan orchards, and cotton plantations. Drive from Tucson south to Nogales, Mexico, and you’ll pass cotton plantations, too.

Most Arizona farmers today are Indigenous, but over 70% of the state’s dwindling water sources go to the $23 billion agriculture industry. In parts of Tohono O’odham land, upstream agriculture has left sinkholes as deep as 15 feet that mark the death of aquifers. The collapsing desert results from centuries of state-sanctioned mismanagement and ethnocentrism.

Hohokam and Pima cultivation of desert washes paved the way for Arizona’s cotton industry, but authorities have consistently overlooked this debt, placing the needs of settlers over the needs of Native and migrant farmers. Even today, as monsoons fail to replenish rivers and aquifers, the federal government continues to provide cotton farmers billions of dollars in cotton subsidies.

Settlers ignored Heraclitus, assuming that Arizona rivers could be stepped in more than once. They gazed on the Sonoran Desert landscape and envisioned an oasis where the colonial past could blossom into the colonial present. Imposing a singular thingness to a memory or river does not honor, and usually forgets, the tensions that historical landscapes hold. Monsoons might carve gaps in the land, but trying to control their impact can create and reinforce gaps in our society.

After five formative years in the Sonoran Desert, my family moved near Jackson, Mississippi. That region has its own landscape history of cotton and racism, but for me, there was no forgetting Arizona’s cotton plantations or forgetting how often life and racism in Arizona forcefully encouraged me to look down.

Color illustration of barrel cactus in bloom

Thankfully my family taught me how to look down with dignity, care, curiosity, and humility. Their stories kept me grounded in the land, its history, and its many species. Like the Sonoran Desert, my family showed me how to appreciate and practice the politics of what Timothy Morton calls “strange stranger,” a recognition that things only get stranger with time, so respect the nuance that comes with apparent familiarity.

The Sonoran Desert was my first of many strange strangers. That region and each strange stranger I’ve encountered since have taught me that the best, most meaningful stories remind us that we’ve seldom been alone in our struggle to be free, so listening to the land and other species before speaking is usually an option.

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