How Does a Cactus Grow?

Cactus Seeds

First, seeds must be spread by a mature adult cactus flowers. This is accomplished through various methods: the seeds are consumed by a many desert animals, so they can be dropped while they are eating them or through the droppings. They can also be blown by the wind, washed around by rain or transported by birds. If a seed lands in an ideal place for it to grow, it will begin to germinate. This happens around one in fifteen seeds.

Once cactus seedling begins to grow, it will only survive if it is under another bush or low tree, which acts as a nurse plant. These nurse plants protect the growing cactus from weather elements, predators and too much sun. The roots may also provide extra moisture for it to grow. Some cacti grow quickly, such as the Cholla cactus. And, some grow extremely slow, such as the Saguaro cactus, which grows at the rate of 1 inch per year.

As a cactus grows from a mature seedling into an actual cactus, it establishes roots before anything else. Cactus roots are surprisingly shallow for their height and weight, with one large long tap root surrounded by two other sets of radial roots which can run several feet away from the base to collect water in the top couple inches of the soil. These roots wrap around things such as rocks under the dirt for anchorage in storms and strong winds.

Once a cactus is strong enough under the protection of the nurse plant, it will most likely overtake the nurse plant as it grows larger than it. This depends upon what type of cactus it is. The sturdy body of the cactus consists of flexible wood ribs that collect in a parallel cylindrical shape. Outside of this is the flesh water-holding tissue and skin. The cactus will sprout growth in a variety of forms; cactus arms, paddles, branches and limbs. These appendages and the torso of the cactus are usually 98-99% water, which is stored in the interior to the ribs in specialized cells called "ground tissue". The water pressing upon the insides of the cell walls is actually what holds the cactus stem erect. The more appendages a cactus has, the older it is.

When a cactus is at full maturity, it produces flowers that turn into fruit in order to reproduce. They appear in spring and are usually in multiple clusters at the tips of the cactus limbs, paddles or branches. These are great treats and nourishment for numerous desert animals, and are pollinated by bats and birds. It is also the way cacti seeds are distributed around the landscape. They beginning as buds, and the flowers on cacti usually open at night and close during the day. Once the flowers are pollinated, it starts to transform into a fruit. This transformation usually takes about a month, or a little longer. Once the fruits are fully ripened they crack open to reveal thousands of seeds, which are then consumed by animals and spread around for germination.