Extreme drought has the cactus as an advantage

by time news

WIf the heat keeps up, our gardens will soon look like the deserts the gunslingers ride through in western movies. Sometimes there are these huge cacti standing around, the ones with the two or more beautifully spread side arms. This growth is found in North America in only one species: Carnegie gigantea, called “Saguaro” in their homeland. However, if the film shows them in front of the majestic mesas of Monument Valley in Utah, then they are probably made of papier-mâché, because the iconic cactus is found almost exclusively in southwestern Arizona and in the southern regions of the Mexican state of Sonora. A 75-foot-tall, 150-year-old specimen once stood in Cave Creek, Arizona, but was blown over by a storm in 1986. According to a newspaper report at the time, it was the largest known cactus at all.

Ulf von Rauchhaupt

Editor in the “Science” section of the Frankfurter Allgemeine Sunday newspaper.

Normally, however, Saguaros rarely grow more than eleven meters high and thus remain smaller on average than those that only grow wild in Mexico Pachycereus pringlei, which, however, does not thrive as beautifully as it grows closer to the ground and also branches more frequently. But also one Carnegie gigantea can grow quite an impressive number of arms, sometimes over fifty. One with 78 arms was sighted north of Tucson in June last year and christened “Shiva” by its discoverers – or by those of its pictures on the Internet.

Birds sometimes build their nests in less densely armoured saguaros, and in 2020 a bald eagle, America’s national bird, was even spotted doing so. Smaller birds like the elf owl also like to nest in cavities in the cactus trunks, but only as tenants. Only woodpeckers can peck cavities in the skin of the cactus, which is reinforced with long, steel-hard spines, and they sometimes do it several times on one cactus. Incidentally, the plant reacts to the injury by forming scar wood, which is more durable than its undisturbed tissue. So when once-inhabited saguaros die and rot, what remains are the wooden cavities that the Sari people of Sonoran used to use as water vessels. Both humans and various birds also enjoy the fruits and seeds.

No small green cactus: The city of Tucson in Arizona courts Amazon with representatives of the local flora.


No small green cactus: The city of Tucson in Arizona courts Amazon with representatives of the local flora.
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Image: Imago

Only lost cowboys – or screenwriters – would come up with the idea of ​​hacking open a saguaro in order to get drinking water in the middle of the desert. Because the risk of injury from the spikes is considerable and the cactus juice is full of alkaloids, which apparently make it so bitter that it is not even known whether these substances have psychogenic effects. If you run out of water in the desert, you better look for a prickly pear of the genus Opuntia around or a spherical Ferocactus wislizeni. These are said to be the only sufficiently voluminous cacti whose juice is reasonably digestible and is guaranteed to leave the consciousness unchanged.

Anyway, damaging saguaros is illegal in Arizona. You’re not even allowed to shoot them, and where they get in the way of construction projects, you can’t take them away without permission. If this is the case, however, it is easy to find someone who would like to have such a shapely succulent in the garden. However, this must then be sufficiently desert-like, because too much rain can be tolerated Carnegie gigantea not at all and then begins to rot at the tips. Saguaros are said to have been spotted with umbrellas stretched over them in some front gardens outside of their natural range.

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