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Echinopsis terscheckii: A typical cactus

The best-known plants that have adapted to the extreme aridity of the desert are the cacti. They’re familiar to us all as the spiky, barrel- or column-shaped plants with water in their trunks.

Echinopsis terscheckii displays the typical characteristics of the cactus family. Whatever the season, you’ll never find leaves on this plant, just several rows of sharp spines. Since water evaporates through leaves, cacti diminish evaporation by reducing their overall surface as much as possible, leading to the evolution of narrow spines instead of leaves. Spines also keep off hungry animals, but you might be surprised to know that, despite their small size, spines also provide shade for the body of the plant. They even help to provide the cactus with water; in foggy weather, droplets of water condense on the spines. This is especially important for cacti living in deserts where it never rains, since they have to get all of their water from the atmosphere.

In cacti, the thick, green trunk takes on the photosynthetic function that leaves perform on other plants. The trunk is also often covered with hair. This hair protects the trunk from intense sunlight and helps keep it from drying out during the day, but also keeps it warm on cold nights. Some other species of cactus, like this Echinopsis, are covered with a layer of wax. All cacti have a special metabolic trick; they can keep their stomata, or pores, closed on hot days to keep too much water from evaporating, then open them at night to take in the carbon dioxide gas they need to make carbohydrates for energy.

The species of Echinopsis shown here branches strongly as it ages and can grow into a very imposing plant more than 7 meters tall. It is native to northern Argentina.



Audio file download
Echinopsis terscheckii: A typical cactus (MP3, 894 KB)

Audio production and copyright: Soundgarden Audioguidance GmbH
Text: Ehrentraud Bayer, Botanischer Garten München-Nymphenburg