Arizona cactus species are under increasing threat from those looking to sell them on the black market, a cactus expert says.

"There's a black market for cactus, just like there's a black market for orchids," Dr. Kimberlie McCue, of Phoenix's Desert Botanical Garden, told Phoenix TV station ABC15 last week.

McCue said that of the 1,800 known cactus species, about a third are considered endangered, adding that poachers will sometimes put smaller cactuses in their pockets to bypass border checkpoints or airport security checks.

Some of the cactuses seized at those checkpoints are sent to the DBG, where they're cared for or sent back to their country of origin, McCue said.

Under Arizona law, it's illegal to move or harvest many of Arizona's native plants, including cactuses, without proper authorization — written permission from the landowner, plus a permit from the Arizona Department of Agriculture. McCue said anyone who notices someone tampering with a native plant should contact the Agriculture Department.

(Also, we know it bothers some of you that Arizona Highways uses "cactuses" and not "cacti" as the plural of "cactus." We're sorry.)