Poaching, habitat degradation, and exotic plant invasion threaten the Chisos Mountain hedgehog cactus, found at Big Bend National Park.
BY JENELL TALLEY
Cacti are hot commodities. The demand for the prickly plants is high, especially the rare populations. Poaching has become common, occurring at an alarming rate. Cacti, consequently, are widely considered the most vulnerable of all plant families, with approximately 26 percent of the species threatened or endangered. The Chisos Mountain hedgehog cactus is one such example.
Joe Sirotnak, a botanist/ecologist at Big Bend National Park in Texas, says about 1,000 individuals of the Chisos Mountain cactus remain. The populations are all found in Big Bend, most within a 30-square mile area. "It's a small population concentrated in one location," Sirotnak says. "If this one population disappears, the taxon will be extinct."
The species, Echinocereus chisoensis, first collected in 1939 around the Chisos Mountains of Texas, occurs in an arid, subtropical climate where the average annual rainfall is between eight and nine inches. Despite the plants' 325-day growing season, numbers remain low.
Illegal collecting, loss of viability, and the inability of present habitat to support reproduction and regeneration all have led to the plant's decline, according to the U.S. Fish and Wildlife Service. Exotic plants, such as African buffelgrass, are invading the cactus' core habitat, are also cause for concern.
As its name implies, the hedgehog cactus is round, spiny, and short, typically growing between ten and 12 inches. The plant is reddish-maroon and becomes greener in the summer. The young areoles near the top of the plant bear cottony, wool tufts. Despite its height, the cactus may have as many as ten stems protruding from it. These stems are often singular, although with age or injury, they sometimes form clumps composed of multiple stems. The cactus' spines are relatively sparse and do not completely cover its stem.
The outer spines are usually a whitish color, or an ashy to pinkish-gray with brown to maroon tips. They are slender and irregular in length. Large, showy flowers bloom on the cactus in March and remain through July. The tri-colored flowers have pinkish to magenta pointed-tip petals, white throats, and a dark crimson base. Greenish-red, club-shaped fruits with wooly areoles and bristly spines adorn the flowers. As the fruits ripen, they split open, exposing warty, oval seeds. The flowers and their fruit are an important food source for pollinators and other insects in Big Bend.
Rodents and jackrabbits have been known to feed on the hedgehog cactus, particularly during extended dry periods. Habitat degradation also contributes to the species' decline, as livestock grazing has eroded the landscape and allowed the invasion of desert shrubs.
A recovery plan was implemented in 1993. Big Bend staff and other cooperating scientists are researching the species' population genetics, breeding systems, pollination biology, and habitat requirements. Park staff monitor two populations of the cactus and are working to establish an experimental population in Big Bend. Sirotnak says the cactus can be de-listed, but that it won't happen any time soon. "In order to de-list the cactus, we need to establish and maintain, for a ten-year period, 50 distinct populations of at least 100 reproductive individuals."
Although poaching may contribute to keeping the plant on the threatened list for some time to come, Sirotnak says he 
understands people's fascination with them. "They're popular because they're rare and beautiful." But, he says, "I prefer to see them in the wild."
