6 Facts About a Cactus

Size

• Cacti vary greatly in size depending on the species. The saguaro cactus reaches up to 48 feet tall, but the tallest species is the cardon cactus, reaching 66 feet tall. The smallest species is the Blossfeldia liliputana, which is short and grows only as wide as a fingertip. Cactus spines can reach 6 inches in length and are used for needles and fishing hooks.

Water Conservation

• Cacti survive in drought conditions. This survival is due to the cacti's ability to protect their water supply. Cacti typically have shallow but expansive root systems able to absorb the rain as soon as it penetrates the ground. That moisture is stored in the stem tissues until there is no water available. Some types of barrel and columnar cacti store enough water to survive from a few months to a few years without additional water.

Multitasking Spines

• A cactus plant's spines not only protect the plant from hungry animals, but in some cactus species, the spines are light in color, reflecting up to 3/4 of the sun's rays. This keeps the plant cool despite hot desert temperatures. The spines of some cactus plants provide insulation during cold night time temperatures, raising the tissue temperatures preventing cell damage.

Areole

• Members of the cactus family are distinguished from other plants by a structure called an areole. This is a little dot on the cactus where the spines, flowers, hairs and new growth develop. On a saguaro cactus, it is a grey, feltlike pad at each spine's base. Other plants have spines, but if there is no areole, it is not a cactus.

Habitat

• Not all cacti species are native to hot, dry deserts. Some cactus plants, like the Christmas cactus, are from rain forests. Other species are native to cold, snow-covered regions and some grow on high, frozen mountain peaks. There are also cacti species native to regions that only see precipitation in the form of fog or dew rather than rain. All but one cactus species are native to the Americas. The exception is the mistletoe cactus, which is native to Florida as well as parts of tropical Africa. Cacti grow in almost every American state. In more than half of these states, the cacti are from the Opuntia genus.

Endangered

• Finding a cactus plant growing wild is an increasingly difficult task. This is largely due to people transplanting them to their home gardens. The mistletoe cactus, for example, is listed by the U.S. Department of Agriculture as endangered. Purchase cacti from nurseries or garden supply outlets. Do not take them from their natural habitats.