Species name: Diablito de Tres Cuernos, Vahl’s boxwood (Buxus vahlii) IUCN Red List status: Endangered Description: Buxus vahlii is a short, slow-growing evergreen shrub or tree that reaches 3-10 feet (1–3 meters) in height, with ovular, dark-green, glossy leaves. It produces delicate, greenish-white flowers with small, rounded fruits growing close to the stem at the base of the leaves. Locally it’s called Diablito de Tres Cuernos (“Little Three-Horned Devil”) because of the distinctive shape of its fruits, which have three horn-like projections, giving this plant an eerie appearance when fruiting. Where they’re found: Buxus vahlii plants can be found in only a few highly restricted sites on the islands of Puerto Rico and St. Croix in the Caribbean Sea. They thrive in shallow, rocky limestone soils that few other plants can tolerate. Populations are found in small, forested patches surrounding areas that have long been developed or disturbed, often clinging to cliffs, ravines, and other rugged limestone terrain. It’s hard to say how many of these plants remain. Studies conducted between 2001 and 2018 documented up to seven remaining fragmented populations in Puerto Rico. There are four known populations on St. Croix, one of the U.S. Virgin Islands, including one within the Sandy Point National Wildlife Refuge and others on the hills south and east of Christiansted. Why they’re at risk: An immense amount of habitat destruction from urban development has placed Buxus vahlii at risk of total extinction. In Rincón, Puerto Rico, for example, the plants’ already restricted habitat and surrounding natural areas are threatened by the construction of a new highway that is unnecessary and opposed by the community. With no conservation attention, these populations continue to decline, unnoticed. On St. Croix, similarly, they’re threatened by urban development, invasive species, and human-caused wildfires. Who’s trying to save them: Buxus vahlii has been legally protected under the U.S. Endangered Species Act since 1985. The law requires the species to be reassessed every five years, but the assessments have not been carried out on that schedule — the first was in 2010, the next in 2018. Notably, they used outdated data, as the only recent field surveys have been conducted on St. Croix. The last field survey in Rincón was conducted in 2001. A new five-year review was initiated in 2023. Can we trust its findings without current data? Meanwhile development continues unabated. While federal agencies such as the EPA and the U.S. Army Corps of Engineers have regulatory authority to intervene, enforcement and active conservation measures have not been upheld. There are no active conservation programs protecting this plant’s populations in Puerto Rico. Why I advocate for this species: I’ve often ventured into the harsh limestone ridges of Rincón, Puerto Rico, where I’ve found myself alone in the one of the rarest of ecosystems. B. vahlii is one of the few species that thrives in the subtropical dry forest life zone, with its shallow, rocky limestone soil and exposure to coastal winds and salt spray. There, the plants are short and chlorotic due to these salty, windy conditions. Photo courtesy Marina E. De León, Ph.D. I’ve also enjoyed guiding community members through these terrains, where I share knowledge about the local flora while learning from their ancestral wisdom. During these times together searching for B. vahlii individuals, we’ve observed old, tall, red-orange Bursera trees that grow together with the native species of Ceiba. While hiking, it’s not uncommon to disturb big, beautiful black witch moths (Ascalapha odorata) that fly off in swaths when we walk by. It’s impossible to capture their true beauty with a camera; the best way to experience them is in the daytime. Navigating these steep hillsides is challenging and reminds me that there are sacred places in the world. The majority of plants we see are short Marias (Calophyllum antillanum). It’s not easy to spot a B. vahlii individual, so finding one is always exciting. You need to look at the leaves and notice the thickness, the glossiness, the shape of the leaf, and its little point at the tip. When I find one, I recognize that due to its rarity, I’m one of the few people on Earth who has ever been this close to one. B. vahlii is not necessarily an interesting plant. Its flowers are not large or fragrant, its leaves are plain and nondescript. It offers no direct economic or practical value to humans, yet its ecological and intrinsic worth are undeniable. Like all species, it has the right to exist, independent of human use or interest. Tragically, because it holds no perceived benefit to people, it has been overlooked, neglected, and steadily displaced by human activity. What else do we need to understand or do to protect this species? To protect B. vahlii effectively, conservation extends beyond the immediate boundaries where the plant is found. A buffer zone is an essential area surrounding the critical habitat that acts as a protective margin, shielding the core habitat from the harmful effects of nearby land use and development. Although B. vahlii itself may not grow within the buffer zone, this transitional space is crucial for maintaining the integrity of the habitat it depends on. It helps reduce the impact of external threats such as pollution, soil disturbance, altered hydrology, and the introduction of invasive species. The need to designate an official buffer zone is necessary due to edge effects, which occur where intact habitat meets the surrounding roads, construction sites, and cleared land. These edge zones experience increased fluctuations in light, temperature, and moisture, along with a higher risk of erosion and the spread of invasive plants or animals. For B. vahlii, which thrives under stable and specific conditions, such changes are probably detrimental, weakening the population’s ability to survive and reproduce. Fragmented habitats with high edge-to-interior ratios are vulnerable, and without an adequate buffer, the microclimatic and ecological conditions needed by B. vahlii degrade. We also need to conduct detailed surveys of the plant’s remaining fragmented habitats. This will allow land managers to understand where B. vahlii grows, as well as the quality and extent of the surrounding environment. Meanwhile ecological studies should examine the species’ interactions with pollinators, seed dispersers, soil microbes, and other components of its dry limestone forest habitats. Data from these surveys help determine the appropriate size and shape of a buffer zone, taking into account soil type, water flow, light exposure, and the presence of mutualistic species like pollinators or seed dispersers. The goal is to preserve not only the current populations, but also the ecological processes that support their long-term viability. Encroaching development poses a significant threat to both the critical habitat and the buffer zones of B. vahlii. Urban expansion can alter hydrology, compact soil, introduce chemical runoff, and facilitate the spread of aggressive non-native plants. Once such changes take place, they could be irreversible. Therefore, to ensure the survival of B. vahlii, development in and around its habitat, including within designated buffer zones, must be strictly limited or prevented altogether. Legal and regulatory protections should be created and enforced. Effective mitigation will require coordination with local and federal authorities to ensure that projects comply with environmental laws, and that buffer zones are respected and maintained. What you can do to help: Please email the following agencies and let them know that the public cares about this plant and we will not allow it to go extinct. U.S. Fish & Wildlife Service (Caribbean Ecological Services Field Office): Email: caribbean_es@fws.gov Puerto Rico Department of Natural and Environmental Resources (Departamento de Recursos Naturales y Ambientales, DRNA): Email: amartinez@drna.pr.gov Environmental Protection Agency (EPA) – Region 2 (Caribbean): Email: mears.mary@epa.gov Here’s a draft letter you can adapt or simply copy and paste to send to these agencies: Dear [Agency Name], I am writing to express serious concern over the status of Buxus vahlii (Diablito de Tres Cuernos), a federally listed endangered plant native to Puerto Rico and the Virgin Islands. This rare species depends on highly specific limestone and serpentine habitats that are rapidly dwindling due to ongoing development, including recent road construction in Rincón. Under both federal and Puerto Rican environmental laws, your agency is legally responsible for protecting this species and its critical habitat. Yet the most recent five-year assessment of B. vahlii reported outdated literature rather than current field data. Without updated surveys, it is impossible to evaluate the true condition of existing populations or the extent of their remaining habitat. I urge your agency to immediately conduct comprehensive field surveys to document the number of plants left and the size and condition of their habitat, and to ensure that all projects near known populations undergo full environmental review. The public is watching closely to ensure Buxus vahlii receives the protection it is legally owed. Safeguarding this species is not only a regulatory duty but also an ethical commitment to preserve Puerto Rico’s irreplaceable natural heritage. Thank you for your attention to this matter. I look forward to your response and to learning what actions your agency will take to ensure the survival of Buxus vahlii. Sincerely, [Your Name] [Locality] [Optional: Affiliation or organization] Previously in The Revelator: Save This Species: The Bettas of Bangka Island The post Save This Species: The ‘Little Three-Horned Devil,’ One of Puerto Rico’s Rarest Plants appeared first on The Revelator.

As the island faces continuous urbanization, this rare shrub has gone unnoticed and ignored for decades, shrinking into near-forgotten obscurity. The post Save This Species: The ‘Little Three-Horned Devil,’ One of Puerto Rico’s Rarest Plants appeared first on The Revelator.