The Grizzly Bear Cactus: Opuntia polyacantha var. erinacea 'Ursina'

A high-altitude botanical masterpiece defined by its extraordinary, silk-like white shagginess.

1. Origin & History of Name The name derives from the Greek poly (many) and akantha (spine), referring to the dense armament of the genus. The varietal name erinacea translates to "hedgehog-like," while the cultivar epithet ursina is Latin for "bear." This specific variety was historically distinguished by botanists due to its exceptionally long, flexible spines, leading to its popular 19th-century designation as the "Grizzly Bear Cactus."1
2. Morphology This taxon is characterized by flattened, ovate stem segments called cladodes. Unlike typical cacti, its epidermis is almost entirely obscured by a dense "fur" of long, white, hair-like spines. These are technically modified leaves emerging from areoles. This white coating serves a dual biological purpose: reflecting intense UV radiation and creating a boundary layer of air to reduce moisture loss through transpiration.
3. Habitat & Origin This is a naturally occurring wild variety native to the high-desert regions of the Southwestern United States, particularly the Mojave and Great Basin deserts. It is a slow-growing, cold-hardy species. Our specimens are ethically propagated via sustainable nursery cuttings to ensure the preservation of wild desert populations.
4. Cultivation Profile

• Substrate: Requires a strictly mineral-based, gritty mix. Use a ratio of 70% inorganic material (pumice, perlite, or crushed brick) and 30% organic matter. In the Indian subcontinent, avoid heavy garden soil which retains excessive monsoon moisture.
• Light: Full, direct sunlight is mandatory to maintain the density and whiteness of the spines. ² In North or Central India, it thrives in open sun; in extreme South Indian summers, provide slight afternoon filtration to prevent scorching.
• Water/Dormancy: Water deeply only when the medium is bone-dry. During the Indian monsoon, keep the plant strictly under cover to avoid root rot. It undergoes a winter dormancy period where watering should be withheld almost entirely. ³

1. Scientific/Historical AnecdoteEarly 20th-century desert explorers often reported that from a distance, large colonies of ursina resembled resting animals due to their "shaggy" appearance. Scientifically, this plant is an evolutionary marvel of "niche construction"—it creates its own micro-climate within its spines, allowing it to survive temperatures ranging from $-20$°C in its native habitat to over $40$°C in tropical arid zones.