“The more trashy your source material is, the longer it takes to make a new variety.” The North Carolina State University crop science professor’s use of “trashy” surprises me. The “trashy” source material he references mainly comes from germplasm collections: usually frozen crop biodiversity repositories, often sourced from landraces—plant varieties stewarded over generations by a community in a particular place—or wild relatives. Breeders incorporate traits into existing cultivars in response to perceived needs, such as increased yield, pest resistance, or tolerance to environmental stressors. Once the new trait is present, the breeding process becomes about ensuring it doesn’t bring along any contaminating phenotypes that might jeopardize the cultivar’s eliteness. This is done through years of selection, weeding out undesirable lines, and ensuring they reproduce true to type.

Variation is crucial for cultivar development, but only insofar as it provides genetic fodder to be incorporated into elite cultivars—those developed by institutional breeding programs. The value of these landraces is measured by whether they contain useful genes. Landraces on their own are devalued in these systems, due to their propensity for “trashiness,” which could mean being unpredictable, low yielding, or, in the words of one plant breeder, “ugly as all sin.” In Seeding Empire, Aaron Eddens recounts one breeder explaining “the landraces are in the hybrids.” Despite their primitive (“trashy”) sources, landraces might possess beneficial genes just waiting to be integrated into an elite variety, making them worth saving (2024, 64).

The end goal of these breeding projects is a distinct, uniform, and stable (DUS) pure line cultivar with qualities “reliant on traits that are known to not be greatly influenced by the environment” (Brown and Caligari 2008, 11). The modern agrifood system is built for uniformity and predictability, which are enforced through maintaining genetic purity and controlling the environment as much as possible, usually through the addition of fertilizers and other chemicals. Purity is the standard by which (conventional) plant breeding is gauged. Without purity, farmers wouldn’t have the consistency necessary to use machinery or grow at the scales the American agricultural industry has come to depend on. Farming is inherently risky, and pure seed is intended to give farmers some control through guaranteed yields. However, no matter how hard scientists try, the environment isn’t static, and plants live in relationship with their surroundings. Breeders are all too aware of the complications of unpredictable environments. The same professor later lamented: “The biggest thing that screws me up every year is the environment,” adding, “plant breeding works [he paused for effect] in the absence of environmental variation.”

Considering STS scholar M. Murphy's definition of unsettling as “the purposeful troubling of particular arrangements so that they might be acknowledged and remade in better, less violent, more livable ways,” I propose impurity as a form of unsettled plant care in increasingly unpredictable environments (2015, 722). Alexis Shotwell writes that although purity is often used to control inherently uncontrollable situations, it does so by ignoring how systems of purification are built on histories of colonialism and hierarchy (2016, 7–8). Emphasizing purity, then, forecloses possibilities for better, more livable futures.

In this vein, I consider Ultracross crops as a case study in impure practices of plant conservation, care, and breeding. The term “Ultracross” was first used by members of the Heirloom Collard Project to describe a highly diverse interbred population of collard greens grown by the Utopian Seed Project (USP) in 2020 as a variety trial. Collards are obligate outcrossers (they can only reproduce through cross-pollination), so there was no intention of saving seeds from these plants, as there was no way to ensure purity. That winter, an unusually late frost killed most of the plants, though some survived relatively unscathed. The intermixed progeny of these survivors became the first generation of Ultracross collards (Smith 2024).

In contrast to the purity required of DUS cultivars or heirloom seeds, the Ultracrosses rely on hybridity, re-arranging genetics to ensure crop futures. Chris Smith, USP’s director, is careful to clarify that the Ultracross concept is not his invention but builds on centuries of traditional landrace growing and stewardship to encourage pre-existing variation (2024, 45). High degrees of diversity means that there is a wide array of genes present, taking the variation out of the seedbank and into the field. Generally, growing Ultracrosses entails ceding environmental control, relying instead on natural selection to encourage adaptation between generations. This is a sort of “tough love” approach to breeding: the plants that survive that season’s environmental conditions are the ones selected for seed saving, regardless of their uniformity. Instead of caring for the strict boundaries that distinguish each cultivar, Ultracrosses encourage caring for variability, because variability means adaptability, and adaptability means greater chances of survival.

The Ultracross are just one example of unsettled plant care through impurity. The Breadlab at Washington State University has developed a population of wheat similar to the Ultracross that they are calling a “Climate Blend.” In a recent interview with NPR, Breadlab founder Stephen Jones explained the logic behind these diverse populations: “If we have a chaotic climate, our strategy is to have genetic chaos in the field [. . .] To strike back, to fight chaos with chaos” (Borunda 2024).

These efforts can be read as subverting the predominating idea that maintaining purity is the only way to care for crop futures. Impurity as unsettled care troubles the systems of knowledge (and crop) production that equate landraces with “trashiness” or “ugliness” or regard them as something that can only be made valuable through controlled incorporation into “elite” cultivars. Part of what makes the Ultracrosses so compelling is how they provide a platform for growers to tell their own stories of engaging with the crops. The longevity of the Ultracross collards won’t come from reproducing generations of stable plants, but rather from the everchanging genes and narratives that emerge as the collards grow with their environments, both social and biological. Embracing impurity points to the potential of endless genetic combinations and the futures this chaos creates.