Invasive Species - Biodiversity for a Livable Climate

Featured Creature: Prickly Pear Cactus

What plant thrives in the harshest landscapes, conserving water like a desert camel, and produces a sweet yet spiky fruit enjoyed for centuries? The Prickly Pear Cactus!

When I’m in the south of France, nothing makes me happier than spending the day by the ocean, taking in the salty breeze and strolling along the littoral. After a long afternoon on the beach, as I make my way home, I always notice prickly pear cacti scattered throughout the local fauna.

Prickly pear cacti are everywhere in the south of France, where I’m from. My mom, who grew up in Corsica, used to tell me stories about how she’d collect and eat the fruit as a kid. So, naturally, last summer, when I spotted some growing along the path home from the beach, I figured—why not try one myself?

Big mistake.

Without gloves (rookie move), I grabbed one with my bare hands. The next 20 minutes were spent with my friends painstakingly plucking hundreds of tiny, nearly invisible needles out of my fingertips. The pain wasn’t unbearable, but watching my hands transform into a pincushion was… unsettling. And to top it all off? The fruit wasn’t even ripe.

For the longest time, I just assumed prickly pears were native to the Mediterranean. They grow everywhere, you can buy them at local markets, and my mom spoke about them like they were an age-old Corsican tradition. But a few weeks ago, while researching cochineal bugs (parasitic insects that live on prickly pear cacti), I discovered something surprising—prickly pears aren’t native to the south of France at all. They actually originate from Central and South America, and were introduced to the Mediterranean from the Americas centuries ago. They’ve since become naturalized.

Curious to learn more, I dove into the biology of prickly pears—and it turns out, these cacti are far more than just a tasty (and slightly dangerous) snack. Their survival strategies, adaptations, and ecological impact make them one of the most fascinating plants out there.

Prickly Pear Cactus Fruit
Credit: Maciej Cisowski via Pexels

Prickly pear cacti belong to the Cactaceae family, and they’re absolute survivors. In spring and summer, they produce vibrant flowers that bloom directly on their paddles, eventually transforming into edible berries covered in sneaky little thorns (trust me, I learned that the hard way).

These cacti thrive in drylands but adapt surprisingly well to different climates. They prefer warm summers, cool dry winters, and temperatures above -5°C (23°F).Their ability to store water efficiently and withstand long dry periods has earned them the nickname ‘the camel of the plant world.’ They can lose up to 80-90% of their total water content and still bounce back, an adaptation that allows them to endure long periods of drought.

They are designed to make the most of their access to water whenever they get the chance. The cactus can develop different types of roots depending on what they need to survive, making them masters of adaptation. One of their coolest tricks? “Rain roots.” These special roots pop up within hours of light rainfall to soak up water—then vanish once the soil dries out.

And then there are their infamous spines. Prickly pears have two kinds: large protective spines and tiny, hair-like glochids. The glochids are the real troublemakers—easily dislodged, nearly invisible, and an absolute nightmare to remove if they get stuck in your skin. (Again, learned this the hard way.)

Nopal (Cactus Pads) – A Nutrient Powerhouse

The term “nopal” refers to both the prickly pear cactus and its pads. It originates from the Nahuatl word nohpalli, which specifically describes the plant’s flat, fleshy segments.

These pads are highly nutritious and well-suited for human consumption, packed with essential vitamins and minerals. They are especially rich in calcium, making them an excellent dietary alternative for populations with high rates of lactose intolerance, such as in India.

Beyond calcium, nopales also provide amino acids and protein, offering a valuable plant-based protein source. They are rich in fiber, vitamins, and minerals, making their nutritional profile comparable to fruits like apples and oranges, explaining their long-standing role in traditional cuisine. From soups and stews to salads and marmalades, they are a versatile ingredient enjoyed in a variety of dishes

Ever wondered how to clean and grill a prickly pear pad at home?

The Fruit – Sweet & Versatile

Prickly pears produce colorful, juicy fruits called tunas, which range in color from white and yellow to deep red and orange as they ripen. Their flavor is often described as a mix between watermelon and berries, while others compare it to pomegranate. Either way, they make for a delicious and refreshing snack.

But before you take a bite, be sure to peel them carefully. If you don’t remove the outer layer properly, you might end up with tiny spines lodged in your lips, tongue, and throat (which is about as fun as it sounds). Once cleaned, the fruit is used in jams, juices, and is even pickled!

Credit: Emilio Sánchez Hernández via Pexels

Prickly pear cacti produce stunning flowers that attract a variety of pollinators, particularly bees. Some specialist pollinators have evolved to depend exclusively on prickly pear flowers as their sole pollen source, highlighting an amazing co-evolutionary relationship. One fascinating example is a variety that has evolved to be pollinated exclusively by hummingbirds, demonstrating the plant’s remarkable ecological flexibility.

If you’d like to see this incredible interaction for yourself, check out the following footage of a hummingbird feeding on a prickly pear flower. Though the video quality is low, the enthusiasm of the couple filming it makes up for it! 🙂

Another fascinating feature of prickly pear flowers are their thermotactic anthers. Okay so yeah, that’s a bit of a mouthful. Basically, the part of the flower responsible for producing pollen, the anthers, have a unique ability to respond to temperature changes—releasing pollen only when conditions are just right for pollination. Prickly pear flowers achieve this through movement; the anthers physically curl over to deposit pollen directly onto visiting pollinators.

You can even see this in action yourself! Try gently tapping an open flower, and watch as it instinctively delivers its pollen like a built-in pollen delivery system.

Once pollinated, the flowers transform into fruit, which then serve as an essential food source for birds and small mammals. These animals help disperse the seeds, allowing new cacti to grow in different areas. But prickly pears don’t just rely on seeds for reproduction, they also have an incredible ability to clone themselves. If a pad breaks off and lands in the right conditions, it can root itself and grow into an entirely new cactus. Talk about resilience!

Like most cacti, prickly pears are tough survivors, thriving even in degraded landscapes. But they go a step further, not just enduring harsh conditions, but actively helping to restore them. The plant’s roots act as natural barriers, preventing erosion, locking in moisture, and enriching the soil with organic matter. Studies show that areas dense with prickly pears experience significantly less soil degradation, proving their role in restoring fragile land.

They also improve soil structure, making it lighter and more fertile, which boosts microbial activity and essential nutrients. They act as natural detoxifiers, absorbing pollutants like heavy metals and petroleum-based toxins and offering an eco-friendly way to restore contaminated soils.

Roots of the prickly pear cactus.
Credit: Homrani Bakali, Abdelmonaim, et. al, 2016

A Tale of Two Ecosystems

Prickly pear plantations are powerful carbon sinks, pulling CO₂ from the air and storing it in the soil. In fact, research shows that prickly pear cultivations in Mexico sequester carbon at rates comparable to forests. A major factor? The cactus stimulates microbial activity in the soil, a key driver of carbon storage.

When farmed sustainably, the CO₂ prickly pears absorb offset the greenhouse gases emitted during cultivation.

Prickly pear cacti have immense capability for land restoration and carbon sequestration, but this potential varies dramatically depending on how they are introduced and managed, and where. In some regions, like Ethiopia, they serve as a lifeline for communities facing desertification. In others, like South Africa, they’ve become invasive, disrupting native ecosystems.

By exploring these two contrasting case studies, we can see how the same plant can either heal or harm the land—and why responsible management is key.

Tigray, Ethiopia: A Natural Fit for Harsh Climates

In Ethiopia, where over half the land experiences water shortages, the prickly pear cactus has become indispensable since its introduction in the 19th century. Arid lands are notorious for unpredictable rainfall, prolonged droughts, and poor soils. But the prickly pear cactus defies these challenges. Requiring minimal water, it provides a reliable food source for both humans and animals, making it an essential crop for small-scale farmers in dry regions.

Prickly pear pads are a crucial livestock feed during droughts, providing moisture and nutrients when other forage is scarce. While it cannot be used as the sole source of nutrition for most ruminants, it’s definitely a necessary supplement in times of drought.

Additionally, the plant’s dense growth creates natural barriers, curbing overgrazing and helping native vegetation recover.

As a food source, prickly pear can be used to supplement human diet. The cactus is an alternative to water-intensive cereals like wheat and barley. With higher biomass yields and significantly lower water requirements, it offers a sustainable solution to food security in drought-prone areas.

Unfortunately, prickly pear cultivation in Ethiopia is under threat from invasive cochineal infestations. These cochineal insects, originally used for dye production, were later introduced outside their native range, where they’ve become agricultural pests, devastating cactus populations.

A cactus infested by cochineal insects
Credit: tjeerddw (CC-BY-NC)

South Africa: When Prickly Pear Becomes a Problem

While the cactus is a valuable resource in some regions, in others, it becomes an invasive species, altering ecosystems and threatening native plants.

In South Africa, prickly pears were introduced by European settlers, but without natural predators to control them, they spread aggressively. Today, they dominate large areas, outcompeting native vegetation and consuming scarce resources like water and soil nutrients. Their dense growth also creates impenetrable thickets that hinder livestock grazing and disrupt local ecosystems.

To control its spread, South Africa turned to biological solutions, ironically using the same cochineal insect that threatens Ethiopia’s prickly pear. In South Africa, cochineal insects have been highly effective at curbing cactus overgrowth, selectively feeding on the invasive species and allowing native plants to recover.

This dual role of the prickly pear cactus—as both a valuable resource and a potential ecological threat—highlights the importance of responsible management. Striking a balance between conservation and cultivation is key to harnessing the plant’s benefits while preventing unintended environmental consequences.

Innovative Uses: From Energy to Eco-Friendly Materials

The prickly pear’s resilience extends beyond its survival in harsh environments—it’s also fueling innovation in sustainability. Scientists and entrepreneurs are finding new ways to harness this plant’s potential, from renewable energy to eco-friendly materials.

In the search for cleaner energy sources, prickly pear biomass is being used to produce biogas and bioethanol, offering a renewable alternative to fossil fuels. Unlike resource-intensive crops, the cactus thrives with minimal water, making it a low-impact solution for sustainable energy. Meanwhile, its juice is being explored as a base for biodegradable plastics. Unlike corn-based bioplastics, which require significant land and water resources, cactus-based plastics are more sustainable and continue growing after harvesting, reducing environmental strain.

Cactus leather, developed by companies like Desserto, provides a sustainable alternative to synthetic and animal-based materials. Unlike traditional vegan leather, which often contains petroleum-based plastics, cactus leather is biodegradable, water-efficient, and durable. As more industries embrace the potential of this remarkable plant, the prickly pear is proving that sustainability and innovation can go hand in hand.

From nourishing communities to restoring degraded land, and generating clean energy, the prickly pear is far more than just a desert plant—it’s a symbol of resilience, innovation, and sustainability. However, its impact depends on careful management. Whether cultivated as a food source or controlled as an invasive species, striking the right balance is key to unlocking its full potential.

And if this article has inspired you to try a prickly pear fruit for yourself, please stick to the store-bought varieties. Unlike wild varieties, cultivated prickly pears are often spineless, making them easier (and safer) to eat. Plus, it would give me, the author, peace of mind knowing that no one has to suffer the same fate I did when I ended up with a hand full of spines after an ill-fated foraging attempt.

Lakhena Park holds degrees in Public Policy and Human Rights Law but has recently shifted her focus toward sustainability, ecosystem restoration, and regenerative agriculture. Passionate about reshaping food systems, she explores how agroecology and land management practices can restore biodiversity, improve soil health, and build resilient communities. She is currently preparing to pursue a Permaculture Design Certificate (PDC) to deepen her understanding of regenerative practices. Fun fact: Pigs are her favorite farm animal—smart, playful, and excellent at turning soil, they embody everything she loves about regenerative farming.

Sources and Further Reading

Featured Creature: Japanese Knotweed

With leaves shaped like a spade, what plant
is known to invade and refuses to fade?

The Japanese knotweed (Reynoutria japonica)

Japanese knotweed flowers (Cbaile19 via Wikimedia Commons)

On a warm spring afternoon, my friend and I explored a creek off the Mill River, in Northampton Massachusetts. Thick green bushes lined the banks, making it difficult to reach the water’s edge. As we scoped for a route through, my friend pulled on a nearby branch, inspecting its leaf.

“Japanese Knotweed,” she identified, grasping the plant at the thick part of its stem and straining to pull it up . “This was my whole summer.”

She’d worked on a farm the previous summer and spent countless hours eradicating weeds, which, as it turned out, were mostly Japanese knotweed.

I too am familiar with knotweed. As a child, I mistook Japanese knotweed’s hollow stems for bamboo, often wielding them as makeshift swords. At the time, I thought of the plant as little more than a plaything, unaware of the complex role it was playing in the ecosystem around me.

Photos courtesy Jim Laurie

Where does Japanese knotweed grow?

Japanese knotweed is native to East Asia in Japan, China, and parts of Korea and Taiwan. The plant was introduced to North America in the late nineteenth century, to be used as an ornamental plant. Its introduction, however, had unintended consequences as it invaded wetland, stream corridors, forest edges, and drainage ditches. Japanese knotweed is a herbaceous perennial plant (a non-woody plant that regrows each year from its roots), that can grow to be up to 11 feet tall, with jointed hollow stems resembling that of, yes, bamboo. So you can forgive my childhood ignorance. The stems are bright green and grow nodes which can range in color from red to purple. The knotweed’s spade-shaped leaves grow from these nodes, with a square base and sharp point. They thrive in full sun but can also grow in partial shade, and do well in a variety of soil and moisture conditions. It can often be observed on the banks of rivers, wet depressions, and woodland edges, or in more built environments, including construction sites and roadways.

During the summer, from the nodes of the knotweed bloom small white and pale green flowers. These little flowers are 3 to 4 inches long, and grow in fingerlike clusters, with each cluster holding a couple dozen flowers.

Japanese knotweed (Larrissa Borck via Wikimedia Commons)

While Japanese knotweed is known as an invasive species in many parts of the world, including throughout the United States, in its native range it plays a much different role. There, it exists in balance with local ecosystems, kept in check by native insects, fungi, and herbivores that have evolved alongside it. Instead of forming dense monocultures that crowd out other plants, knotweed grows as part of diverse plant communities, coexisting with a wide variety of species.

Unlike in North America and Europe, where few animals or insects consume it, knotweed supports a variety of wildlife in its natural habitat, and its nectar is enjoyed by bees and butterflies, especially in late summer when other flowers have faded. Insects such as the aphid Aphalara itadori and various beetle species naturally feed on knotweed, limiting its dominance and allowing native plants to thrive alongside it. Some fungi, like Mycosphaerella leaf spot, help regulate its growth, preventing the unchecked spread seen in non-native environments. These interactions ensure that Japanese knotweed remains just one part of a broader ecosystem rather than an overwhelming force.

Ecologically, Japanese knotweed plays an important role in nutrient cycling and soil formation. Its deep, extensive rhizome network helps stabilize slopes prone to erosion in Japan’s more volcanic landscapes, helping to prevent landslides and maintaining soil structure. Additionally, the plant’s decomposition contributes to organic matter in the soil, enriching the surrounding environment.

But when introduced elsewhere, many of these ecological checks and balances are missing, allowing knotweed to spread aggressively and disrupt local biodiversity.

How does it spread?

Japanese knotweed reproduces through both seeds and rhizomes, an underground root-like system which produces shoots of new plants, coming up through the earth. As much as two-thirds of the plant’s biomass is stored in this network.

Seeds of the Japanese knotweed (Famartin via Wikimedia Commons )

The knotweed can be found around the world, far from home. It was introduced to the United Kingdom in 1825 and has since spread across Europe. The majority of Japanese knotweed populations in Europe descend from a single female genotype, though hybridization with related species has introduced some genetic variation. This female genotype is able to receive pollen from a close relative, called the giant knotweed. The combination of these two plants produces a hybrid known as the Bohemian knotweed, which is also spreading across Europe.

In North America, however, the Japanese knotweed reproduces differently than its European counterpart. Even though the European female clone is widely dispersed around the United States, this clone is not the only genotype present. Populations of both male and female Japanese knotweed have been identified across America. The female Japanese knotweed does not produce pollen and primarily spreads through those rhizomes, though it can also reproduce via seeds when pollinated by a related species. Male Japanese knotweed, on the other hand, do produce pollen, as well as occasionally producing seeds.

Impact

Japanese knotweed grows in thick clusters, emerging during early spring time and growing quickly and aggressively. This dense stand of plants crowds out native vegetation, depriving them of resources needed for reproduction and survival.

Japanese knotweed by the water (Dominique Remaud viaWikimedia Commons)

Japanese knotweed thrives in moist, shaded environments. On stream banks, it outcompetes native grasses and shrubs, reducing biodiversity. This lack of diversity along the bank causes instability, and makes it more likely that the soil will shear off during flooding, increasing the amount of sediment deposited into the water. This erosion sends soil and Japanese knotweed seeds into the creek, allowing the plant to spread downstream and further destabilizing the stream bank.

Foraging Japanese knotweed

The young, spring shoots of Japanese knotweed are not only edible, but also delicious! The plant has a tart, slightly sweet taste, similar to that of rhubarb. It can be turned into a jam, put in salads or a stir fry, and used as a crunchy addition to sushi. Where it is native in East Asia, knotweed has been used in traditional medicine for hundreds of years. Owing to the plant’s invasive nature, practicing responsible foraging is crucial to avoid accidentally spreading the knotweed populations. In order to properly dispose of the leftover plant matter, it must be boiled, burned, or thoroughly dried out before discarding in order to ensure that no knotweed is spread. Foraging and eating Japanese knotweed can be a way to help control the plant, through the repeated cutting of the stems. The following video shows a recipe for homemade Japanese knotweed pickles!

Managing knotweed

Due to its dense clusters and deep root system, once established, Japanese knotweed is incredibly difficult to remove. Manually, populations can be managed through repeated cutting, though complete removal of rhizomes is extremely difficult and can sometimes lead to further spread of the knotweed. When it comes to cutting, the stems of the plant must be cut three separate times during the growing season in order for this to be an effective treatment. In terms of digging up the roots, this can be very labor intensive, and the process of digging Japanese knotweed can unintentionally cause the spread of rhizome fragments, which can result in even more Japanese knotweed on your hands!

Japanese knotweed’s spade-shaped leaf (Flocci Nivis via Wikimedia Commons)

Through dedicated work, such as that of my friend who spent three months eradicating Japanese knotweed on her farm, the populations and impacts of the plant, when invasive, can be mitigated. With a little time and effort, you can help control knotweed in your own backyard…and maybe even harvest some for dinner.

Helena is a student at Smith College pursuing psychology, education, and environmental studies. She is particularly interested in conversation psychology and the reciprocal relationship between people and nature. Helena is passionate about understanding how communities are impacted by climate change and what motivates people towards environmental action. In her free time, she loves to crochet, garden, drink tea, and tend to her houseplants.

Sources and Further Reading:

Featured Creature: Staghorn sumac

What berries grow in crimson towers,
With tangy taste that puckers and sours?

Staghorn sumac! (Rhus typhina)

Growing up, the slim outline of the staghorn sumac lined the perimeter of my backyard, reaching out its limbs, dotted with dark red berries. In the bored heat of summer, my brothers and I would grab the plant’s thin trunk and shake, raining berries down on us and gathering as many in our hands and pockets as we could.

These wide and angular branches give the staghorn sumac its name, resembling the sharp antlers of a deer. And much like the thin, soft velvet that covers young antlers, the staghorn sumac’s stem is lined with a fine velvety layer of hair (or trichomes). In addition to serving as a protective layer from insects and the elements, this fuzz distinguishes the staghorn sumac from its common relative, the smooth sumac. These two plants share quite a few traits, both having pinnate (feather-like leaves) and producing red fruit. However, the smooth sumac, as the name suggests, lacks the fine velvety texture on its stems that characterizes the staghorn.

Budding branch of staghorn sumac (WikiMedia Commons by Krzysztof Ziarnek)

Planting roots

Beyond its striking leaves and vibrant berries, the staghorn sumac has a unique way of multiplying and thriving in the wild.

Growing from a large shrub to a small tree, the staghorn sumac ranges in size from about 3 to 30 feet in height. It is native to the eastern half of the United States and flourishes on the edges of forests, clearings, and dry, rocky, or gravelly soils.

The staghorn is a colony forming plant, meaning that they cluster in groups of genetically identical clones, connected through an underground network of roots. The plant reproduces new clones via a process known as root suckering, where vertical growths originate from its root system. In addition to producing colonies, the staghorn sumac also naturalizes through self seeding, the dispersal of its own seeds.

The flowers of a staghorn sumac are crimson, hairy, and bloom through May to July. Berries form tightly pyramidal clusters and are usually ripe by September, persisting into the winter, even after the staghorn sumac has lost its leaves, though this timeline can vary by geography.

Staghorn sumac in the winter (photo by author)

The staghorn sumac is dioecious, male staghorn sumac and female staghorn sumac flower separately. The female staghorn sumac produces flowers and seed, while the male staghorn sumac only produces flowers. Due to the staghorn sumac’s colony forming habits we just learned about, and while not always the case, groves of predominantly female-only or male-only trees can be found. The colony of staghorn sumacs that grew around my childhood backyard were all seed bearing, and therefore a colony of female-only sumacs.

Staghorn sumac flowers (Trent Massey via iNaturalist)

Berries and Beyond

The berries produced by the female staghorn sumac hold the same shade of deep red as the flowers, but also have finer hairs and a denser, round body. As children, my brothers and I were convinced that these velvety, red berries were poisonous, and we handled them with a slight air of suspicion. However, despite their vibrant color, the berries lining our pockets were not poisonous. While brightly colored fruits may have a reputation for being dangerous, many use bright colors to attract different pollinators. In this case, the bright Staghorn sumac berries are an edible fruit that has been used by humans for centuries. They are high in vitamin c and have a strong, tart taste. Upland game birds, songbirds, white-tailed deer, and moose also eat the tree’s leaves and twigs, while rabbits eat even the plant’s bark.

The staghorn sumac has been utilized by Indigenous peoples in North America for a variety of different purposes—including traditional medicine—over hundreds of years. The fresh twigs of the staghorn sumac, once peeled, can be eaten, and have been used in dishes such as salads. These same twigs, along with the leaves, can be brewed into medicinal tea, traditionally used to relieve post pregnancy bleeding, alleviate respiratory conditions such as asthma, and assist in digestion. In addition, the roots of the staghorn sumac have historically been used for their supposed antiseptic and anti-inflammatory properties.

A common use for sumac berries is to make sumac-aide, a lemonade-like beverage with a strong, tart taste. Sumac-aide has been used for its believed medicinal properties, or simply as a refreshing summer drink. Sumac berries are ready to be harvested and used for culinary purposes during late summer, once they turn dark red in color.

Staghorn sumac (Josveo5a via WikiMedia Commons)

The staghorn sumac trees that once grew lush in my childhood backyard are all gone now, leaving an empty patch of dirt in their wake. Although my family does not understand the events that lead to their demise completely, potential disease could be one contributing factor. The staghorn sumac is a resilient tree that is able to flourish under a variety of conditions. However, like all plants, the staghorn sumac is still susceptible to disease. Fungal diseases such as anthracnose, powdery mildew, and root rot, and bacterial diseases such as leaf spot can infect and kill groves of the staghorn sumac. In addition, invasive pests such as Japanese beetles can strip the staghorn sumac by skeletonizing its leaves and damaging flowers.

Recently, I was walking along an icy boardwalk near my childhood home and noticed little fuzzy flowers, bright red against the white snow. It took me a closer inspection of these cute crimson flowers to notice the large group of staghorn sumac arching above the boardwalk and over my head. The trees bore their rich red flowers despite the other snow encrusted barren trees of the landscape.

If you know where to look, the staghorn sumac is everywhere, dotting the sides of highways, bike paths, playgrounds, and perhaps even your own backyard.

Helena Venzke-Kondo is a student at Smith College pursuing psychology, education, and environmental studies. She is particularly interested in conversation psychology and the reciprocal relationship between people and nature. Helena is passionate about understanding how communities are impacted by climate change and what motivates people towards environmental action. In her free time, she loves to crochet, garden, drink tea, and tend to her houseplants.

Sources and Further Reading:

Featured Creature: Cheatgrass

What plant plays an important role in the grasslands of its native hemisphere, but alters soil moisture and fire regimes when introduced in North America?

Cheatgrass (Bromus tectorum)!

A cheatgrass seed had needled its way into my skin again. I thought that I had freed myself of the cheatgrass when I came back east, to the land of ample water and broad leaves, and threw all of my camping gear into a dark corner of my bedroom. This was not so – it was hiding out in my sock drawer. When I pulled up my socks, I dragged the pointed tips of the cheatgrass seeds up my ankles, and I was once again somewhere out west, nursing the delicate white surface wounds that they left. I was, for the first time, not grateful for the tight warmth-trapping weave of my wool hiking socks – it is highly adept at locking the lance-like grass seed into a comfortable chamber from which it can prod at my ankles. The cheatgrass survived the washer and the dryer and my prying fingernails, survived my desperate attempts to wrench it out of my socks and into the campfire. Cheatgrass burns fantastically well– it’ll ignite from marshmallow-toasting-distance and beyond.

My cheatgrass came with me from Wyoming months ago. Out there, it rolled for miles across the sagebrush steppe, slowly but surely creeping into every space between every shrub. The site where I gathered the seeds into my socks smelled more of earth than sagebrush, which was unusual for the basins where I’d been working. My boss Rachel and I hopped down out of our work truck and took in our site: some sagebrush, sure, but only a few dashes of it scattered between rolling hills of crisp, flame-red cheatgrass. The site was nearly silent; I found myself missing the usual distant whirrr of farm machinery and the cacophonous cry of a startled sage grouse. We were instead accompanied by the whistling of wind and the knowledge that we would be blowing dust into our handkerchiefs for a few days.

The Sagebrush Steppe near Big Jacks Creek Wilderness, Idaho, has been almost entirely taken over by cheatgrass.

“Downy Brome”

Some call cheatgrass “downy brome”, which is a perfect term for it in the early spring when it hasn’t grown into its wretchedness. In early spring, when its long awns have not yet grown stiff and sharp, it is a soft and elegant plant. Its leaves fall in a gentle cascade from the long stem. The downy brome rolls over hillsides and whispers to its sisters in the breeze; as they dry in late summer, the wind knocks the heads of their seeds against one another, and they are scattered to the ground to start their cycle anew. When the cool season rains end and they’ve sucked up all the water they can from the parched earth, their chloroplasts finally falter, and the grass turns a faint purple-red from the awn-tip up. In spring, the dusty green tones of the sagebrush and the brightly-colored grass dapple the landscape. By summer, the sagebrush is nearly overtaken by an orange-brown, foreshadowing the fire which cheatgrass so often fuels. The grass sticks its seeds through your shoes and between your toes and into your socks and the hems of your pants. It doesn’t matter if you stop to pull them out– you will have just as many jabbing and nudging away at you after you walk another ten feet through their swaying abundance. It is useless to shake them out, too. You must pull them, piece by piece, out of your hair and your tent and your boots, and cast them to the ground. This is just what they wish for– you are seeding them for next year.

A rugged invader

Humans introduced cheatgrass to the Northeastern United States by accident sometime around 1860. You can find it in many places around New England, but in the presence of such an overwhelming amount of water, it often fails to compete with its fellow grasses and is relegated to cracks in sidewalks and highway islands full of compacted, inhospitable soil. Cheatgrass seems lost on this coast; few in the East know what it is or why it’s here. It is a plant surviving as plants do, regardless of the “invasive” status we’ve thrust upon it. In the West, however, its success is something wicked and wonderful.

Any water from the winter’s snowmelt or early spring rains gets sucked up by the eager roots of the cheatgrass, leaving little for the still-sprouting native grasses, forbes, and shrubs, even as their taproots probe deep into the earth. Ecologists curse the plant for its brutal efficiency in driving out those native to the arid steppe; birders lament the loss of woody habitat for their feathered favorites; ranchers sigh at the sight of yet another dry, nutritionally-deficient plant that even their toughest cow is loath to graze. And there is, of course, the fire. Cheatgrass dies and dries in the early summer, long before native grasses do, providing an early fuel source for the ever-lengthening fire season.

Cheatgrass seeds
Jose Hernandez, USDA (Public Domain via Wikicommons)

The seeds lie in wait in the earth, and in the spring, they unfurl their new leafy heads and emerge from between blackened sagebrush branches. In the grass’s native range in Europe and Southwestern Asia, the plant is no worse or better than any other; it just is. Moths and butterflies lay their eggs along its edges. Ungulates nibble it slowly as their eyes each search opposite directions for the next snack.

Nearly all of the existing research on the plant explores its role far from home, in the United States. It is grass, and it would be hard to imagine that here on the other side of the world, some field tech is cursing its very existence. You’d never know from looking at the cheatgrass that ranchers and federal scientists alike have spent years dousing their own lands in herbicides with the hope of its extirpation. We humans have of course played our role in keeping the cheatgrass strong even as we try to drive it out, since cheatgrass, like many invasives, is far better at taking over already-disturbed soils where the native plant communities and biological soil crusts have been weakened. As extreme wildfires, agricultural use, overgrazing, and the general ravages of climate change continue to impact larger and larger regions, so too does the invasive capacity of the cheatgrass.

I wore a different pair of socks hiking that day for fear of bringing more cheatgrass to Connecticut. It was silly, though; the cheatgrass already knows this land well.

Jasmine

Jasmine Gormley is an environmental scientist, writer, and advocate from New Hampshire. She holds a BS in Environmental Studies from Yale, where she conducted research in plant community ecology and land management. She aims to obtain a degree in environmental law. As a first-generation college student, she is passionate about equity in educational and environmental access, and believes that environmental justice and biodiversity conservation are often one and the same. In her spare time, you can find her rock climbing, foraging, and going for cold water swims.

Sources and Further Reading:

Featured Creature: Asian Giant Hornet

Photo from wikipedia.org

What creature comes from Southeast Asia, is the biggest of its kind, eats animals we need, and has been tried and convicted of murder in the court of public opinion?

Meet the Asian Giant Hornet!

Warning: This is not your warm and cuddly Featured Creature.

It was a warm and pleasant day last summer, and some of us Bio4Climate folks were entertaining out-of-town guests at our Miyawaki Forest in Cambridge, Massachusetts. During lunch, a biologist from central Europe expressed horror at the appearance of a “new” insect. She described it as the largest wasp she had ever seen (the differences between wasps and hornets are primarily coloring and size).

What do you think?

Photo: Gary Alpert
https://en.wikipedia.org/wiki/File:Vespa_mandarinia.jpg

Indeed, it was a new insect in the Western Hemisphere – it landed in France in 2004. Before then, its home had been limited to Southeast Asia and Japan for 16 million years as a forest dweller that mostly lives in subterranean nests. Those in the know suspect that it somehow hitched a ride in pottery imported from China. Perhaps it’s a bit surprising that the hornet’s international travels took so long, given that globalization has been going on for many centuries.

Asian Hornet Size Comparison — Relative sizes for comparison, from vespawatch.be CC BY 4.0 license

In many places where this creature newly appeared, authorities put out the alarm and asked citizens to take a photo of it with their cell phones but do not touch it or disturb it in any way! It has a quarter-inch stinger and plenty of venom for repeated attacks. It’s rarely lethal to humans, but the sting has been described as driving a hot nail into your flesh. “Just tell us where you saw it and we’ll send in experts to try to find its nest” – no simple task with nests that are usually underground.

As it happens, people mostly mis-identified other black-and-yellow wasps as Asian Giant Hornets so the alarm was somewhat false – but the threat was real. And the spread could happen quickly, as it did in Belgium:

Asian hornets in Belgium: *August* ***2018***, ©Vespa-Watch

Asian hornets in Belgium: *August* ***2020***, ©Vespa-Watch

Asian hornets in Belgium: *July* ***2022***, ©Vespa-Watch

If these maps resemble our recent and devastating infectious global invasive-species explosion, Covid-19, it’s not a coincidence. Zoonotic diseases – illnesses that jump from nonhuman animal hosts, including insects, to humans – present in patterns that resemble the spread of hornets. The threat of another potential pandemic, albeit non-microbial, should ring alarm bells everywhere.

But that’s a story for another day. The current question is, “Why are we so worried about the Asian Giant Hornet?” True, it’s a painful sting, but is there something else?

Yes, indeed.

This hornet’s favorite food is honey bees. The bees don’t stand a chance against these aggressive and much larger adversaries. A small crew of invaders can decimate a nest of thousands of bees in a few hours. Their powerful jaws quickly decapitate their victims; they proceed to chew up the body into “meatballs” and deliver the meals to their own offspring. Hence the nickname “murder hornets,” although that is rather overly dramatic – all carnivores eat other creatures. After all, it’s an essential job in almost all ecosystems to keep a habitat’s checks and balances are working.

Bees in the hornet’s native South Asian habitat do have a defense, at least against only one or two invaders. A team of bees surrounds the hornet, beats their wings, and raises the temperature beyond hornet tolerance – and to victory!

Photo: Takahashi
A defensive ball of Japanese honey bees (*Apis cerana japonica*) in which two Japanese hornets are engulfed, incapacitated, heated, and eventually killed. This defense is also used against the Asian giant hornet.

Unfortunately, non-Asian bees haven’t had millions of years to figure out how to smother hornets.

Since honey bees are essential pollinators for many crops in addition to producers of honey, the appearance of Asian Giant Hornets in North America in 2019 mobilized beekeepers and agriculture big time. In 2020 officials warned that if the hornets become established, they “could decimate bee populations in the United States and establish such a deep presence that all hope for eradication could be lost.” As with many invasive species, when they establish themselves in a new place their natural predators usually don’t come along, and that disrupts the ecosystem’s function.

In the hornet’s defense from a homo sapiens perspective, it has some redeeming qualities. It’s only fair to say that it also attacks what we would call agricultural pests, and its larval silk proteins “have a wide variety of potential applications due to their [many] morphologies, including the native fiber form, but also sponge, film, and gel.”

Finally, given that every animal eats and gets eaten eventually,

In some Japanese mountain villages, the nests are excavated and the larvae are considered a delicacy when fried. In the central Chūbu region, these hornets are sometimes eaten as snacks or an ingredient in drinks. The grubs are often preserved in jars, pan-fried or steamed with rice to make a savory dish called hebo-gohan. The adults are fried on skewers, stinger and all, until the body becomes crunchy.

In gastronomy, there is hope!

P.S. “Vespa,” by the way, is the genus of wasps and hornets. So the next time you’re riding your bike and you hear an ever louder buzzing behind you, be grateful when it’s a gas-guzzling scooter and not its eponymous insect.

Extra featured-creature feature, red in tooth and claw:

By Adam Sacks

Sources:
https://www.discoveringbelgium.com/asian-hornets/
https://en.wikipedia.org/wiki/Asian_giant_hornet
Alfred Lord Tennyson In Memoriam A. H. H., 1850:
Who trusted God was love indeed
And love Creation’s final law
Tho’ Nature, red in tooth and claw
With ravine, shriek’d against his creed

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