A boojum is one of three things depending on where you encountered the word: a fictional creature from a Lewis Carroll poem, a bizarre-looking tree native to the deserts of Baja California, or a type of topological defect studied in physics. The literary origin came first, and the other two meanings borrow directly from it. Here’s what each one is and why they all share the same strange name.
The Literary Boojum
The original Boojum appears in Lewis Carroll’s 1876 narrative nonsense poem, “The Hunting of the Snark.” In the poem, a crew of oddball characters sets out to hunt a creature called a Snark. The twist, revealed at the end, is that the Snark turns out to be a far more dangerous variety: a Boojum. Anyone who encounters a Boojum simply vanishes, “softly and suddenly” ceasing to exist. Carroll never describes what a Boojum looks like or explains the mechanics of the disappearance. That deliberate vagueness is the point. The poem is a work of literary nonsense, and the Boojum functions as an absurd, unexplained threat lurking inside an already absurd quest.
The word has since taken on a broader cultural life as shorthand for something elusive, unknowable, or unexpectedly dangerous. It’s this quality that inspired scientists to borrow the name for two very different real-world phenomena.
The Boojum Tree
The boojum tree is a tall, spindly desert plant that looks like nothing else on Earth. Imagine a pale, tapered column rising from the ground like an upside-down carrot or a giant candle, with short spiny branches sticking out at odd angles. Large specimens can reach 18 meters (about 54 feet), though the trunk may only be 50 centimeters (roughly a foot and a half) wide at the base. The effect is so surreal that the English botanist Godfrey Sykes reportedly named it after Carroll’s creature upon first seeing it, feeling that only a nonsense word could do justice to something so strange.
Its scientific name is Fouquieria columnaris, and in Mexico it’s commonly called cirio, meaning “candle.” It’s a stem succulent, storing water in its thick trunk to survive long dry spells. The tree is native to the northern deserts of the Baja California peninsula, ranging from roughly southeast of San Quintín in the north down to the Volcán de Las Tres Vírgenes area in Baja California Sur. A small, isolated population also exists across the Gulf of California in Sonora, but the vast majority grow on the peninsula’s Pacific side.
Where It Grows
Boojum trees favor well-drained granitic or volcanic soils on hillsides and alluvial plains. They grow poorly in caliche (calcium carbonate-rich soil) or very rocky ground. Most populations benefit from a strong Pacific maritime influence, and in the northern third of the range, dependable coastal fog supplements highly variable winter rainfall. Further south, fog is rare, rain falls in two seasons, and summer temperatures run high. Annual rainfall across the boojum’s range swings from essentially zero in drought years to over 500 millimeters during hurricane seasons. In the northernmost populations, near San Quintín, boojum trees grow between 400 and 800 meters elevation alongside California juniper, agave, barrel cactus, and chaparral shrubs.
Flowering and Growth
Boojum trees break dormancy in late summer to early fall, when clusters of small, tubular, honey-colored flowers emerge from branch tips. Bees and hummingbirds are the primary pollinators. Growth is extremely slow. The trees can live for hundreds of years, adding height at a pace measured in centimeters per year, which partly explains their conservation sensitivity. A large boojum you see today may have been growing since before Columbus.
Conservation Outlook
The Baja California peninsula faces mounting pressure from overgrazing by free-roaming livestock, off-road vehicles, agricultural expansion, and rapid human population growth. Climate change compounds all of these threats. Because boojum trees are endemic to a narrow geographic band, shifts in rainfall patterns or temperature could push populations beyond their tolerance. The northernmost populations, which depend on fog and variable winter rain, may be especially vulnerable. Conservation efforts in the region increasingly focus on protecting endemic species through expanded reserves and better understanding of how desert plants will respond to a warming climate.
The Boojum in Physics
In condensed matter physics, a boojum is a type of topological defect that forms on the surface of certain exotic materials, most famously superfluid helium-3. Superfluid helium-3 is liquid helium cooled to near absolute zero, where it flows without friction and develops complex internal structure. The “defect” isn’t damage in the everyday sense. It’s a point on the surface where the material’s internal orientation can’t be smoothly defined, like the way hair on a tennis ball always has at least one cowlick no matter how you comb it.
The physicist N. David Mermin coined the term in the late 1970s, choosing “boojum” precisely because it sounded ridiculous. He later wrote about the experience, describing it as a “successful effort to make the ridiculous word ‘boojum’ an internationally accepted scientific term.” The name stuck because the defects share a quality with Carroll’s creature: they appear unavoidably, as a mathematical consequence of the surface geometry. The Poincaré-Hopf theorem guarantees that on certain surfaces, these point defects must exist even in the ground state (the lowest-energy configuration). You can’t comb them away. Boojums also appear in the study of liquid crystals and have been theorized to form on the surfaces of neutron superfluids inside neutron stars.
Why One Word Covers All Three
Each use of “boojum” traces back to the same impulse: encountering something so odd that ordinary language falls short. Carroll invented the word for a creature that defied description. A botanist borrowed it for a tree that looks like a hallucination. A physicist adopted it for a mathematical inevitability so counterintuitive it needed a name with no prior baggage. The word works in all three cases because it carries no meaning of its own, only the feeling that something profoundly weird is going on.