It's not easy to be a cactus — surviving in a scorching environment with little water is a pretty tough task for most plants. Some cacti, like the saguaro, have adapted by taking their sweet time to grow. In fact, saguaro cacti often reach just 1.5 inches in the first 10 years of their lives. Growing their iconic arms — often featured in old Western films and desert art landscapes — can take 50 years, or even up to 100 years in drought-like conditions.
These slow-growing giants are found wild only in the Sonoran Desert, which stretches from southeastern California across southwestern Arizona and into Mexico. Despite their vulnerabilities, saguaro are important plants in the Sonoran ecosystem, providing fruit for birds, nectar for bats and other pollinators, and superb nesting spots for birds and other wildlife — which is why these colossal cacti are legally protected native plants in Arizona.
The scientific name for the saguaro — Carnegiea gigantea — is named for philanthropist __.
Numbers Don't Lie
Height (in feet) of the largest recorded saguaro cactus
78
Estimated species of cacti globally
2,000
Species of cacti found wild outside the Americas
1
Diameter (in centimeters) of Blossfeldia liliputana, the world's smallest cactus
2.5
There's a special census for saguaro cacti every 10 years.
How do scientists know how many saguaros exist in the U.S.? Turns out, they count and record them, in a fashion similar to how the federal Census estimates the nation's population of humans. Scientists at Saguaro National Park in Arizona first began the cactus count in 1990 as a way to track species health and numbers, syncing the enumeration with the federal Census. Every 10 years, scientists and volunteers count the number of cacti in randomly selected areas of the park to calculate how many saguaro likely exist in the preserve as a whole. The work is labor-intensive, requiring census-takers to hike to desolate areas of the park and record each cactus' GPS coordinates, height, number of arms, and other information. In 2020, that work totaled more than 3,500 hours from staff and a group of more than 500 volunteers. The most recent report shows the saguaro population nearly doubled from the 1990 count, totaling around 2 million in 2020, though it's possible up to 20% of baby saguaro could be missed, since they're so small and difficult to spot.
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