The Life of a Cactus

Reproduction

• The life of a cactus can start in several different ways. Cacti can reproduce asexually, which happens when a new plant is grown from the joint of a parent plant. This results in a new cactus that has an identical genetic makeup to the parent.

  A cactus may also start from sexual reproduction, which occurs when the flowers of the female plant are pollinated by the male. Many cacti have both male and female parts, but need to be pollinated by a different cactus. These plants are considered self-sterile. Birds and insects often aid in the pollination and in the spread of seeds, and are attracted to the cacti by brightly colored flowers and the secretion of nectar.

Growth Rate

• Many cacti have a slow, irregular growth rate that is based around water usage and conservation. The slower the cactus grows, the less water it needs to fuel the growth processes. In many cases, the majority of the plant's growth will occur during the rainy season and taper off during the drier months. Cacti kept as houseplants will generally grow fastest in the summer months.

  The long-lived, massive saguaro is one of the slowest-growing members of the cactus family. It can take up to 15 years for the saguaro to reach a foot in height, and it does not begin to develop its distinctive arms until about 75 years of age. By the time these cacti reach the old age of 150 years, they can weigh up to 8 tons.

Water Retention

• Much of the life of a cactus is centered around getting and keeping water. While many deciduous plants are dark green in color, these heat-tolerant plants tend to be lighter in color or covered with a fine coating of white hairs. This is to help reflect more of the sunlight than is absorbed. Plants have structures called stomata that transfer gases, such as carbon dioxide and oxygen, between the plant and the environment. The stomata of the cacti can close during the hottest periods of the day to minimize water loss. Water loss is also minimized by the cacti's ability to quickly seal off wounds to tissues, as well as the ability of some to store water below-ground in root systems.

Environmental Impact

• Whether in the wild or in the garden, cacti have an impact on their environments. Their pollen and nectar are a food source for animals from butterflies and hummingbirds to bats. Birds excavate holes in the side of large cacti for nests; the hardy nature of cacti makes them well adapted to heal damage done by the birds with little effort.

  Cacti have long been a food staple of people who share its native environment. The flesh of some types of cacti can be made into jams, jellies and salsa. Cacti sap has medicinal uses, such as the relief of pain from burns. Young, new growth can be harvested and used like lettuce. Spines have been used to stuff bedding, while it may also be grown as a host to insects, like the cochineal scale insect, which was collected and crushed to make dye.