Roots Roots are important to plants. They absorb water and minerals from the soil. They carry water and minerals to the stem. They help to anchor the plant in the soil. They store food and water for future use. #1

There are two major types of roots. Fibrous Roots Taproots #2

Taproots The taproot is the primary root that grows down from the stem. Cacti Adaptations -Taproots Some cacti have a taproot. This taproot allows the plant to store food and water underground where they are away from the hot, drying weather. Taproot cacti are usually small because the taproot is not able to hold up a lot of weight.

Fibrous roots are small lateral roots that spread out just below the soil surface. Fibrous Roots Cacti Adaptations - Fibrous Roots Most cacti have fibrous roots that spread out widely from the plant and grow close to the ground’s surface. Some prickly pear roots spread 10 to 15 feet away from their stems. This adaptation provides more roots to absorb rain water.

Root Hairs Smaller root hairs grow from the feeder roots. They increase the surface area of the roots, which allows them to absorb more nutrients and water.

Cactus Adaptations - Root Hairs When rains come, a cactus’ fibrous roots quickly grow tiny root hairs to absorb water and nutrients. This adaptation lets the roots collect even the smallest amount of moisture from a light rainfall. After the ground dries, the root hairs die and disappear. This allows the cacti to live off their stored water, and they will not have to use any moisture and energy to keep the root hairs alive. #4

Cacti Root Adaptations Some larger columnar cacti will have both fibrous roots and a taproot. The taproot helps anchor the heavy plant and also allows it to reach deeper water supplies. The fibrous roots are spread out widely so they can collect surface water when it rains. #3&4 #2a&b

The one thing that separates cacti from the other succulents is the way their spines grow. Cacti are the only succulents that grow their spines from areoles. New growth (flowers, segments, spines) of the cacti comes from the areoles. Some cacti will have leaves, but they soon fall off. Cacti Adaptations - Why is a Cactus a Special Succulent? #5

Leaves form on a new prickly pear pad. These leaves will soon fall off. Cacti Adaptations - Why is a Cactus a Special Succulent? Remember: All cacti are succulents, but not all succulents are cacti. To be a cactus, the plant has to have areoles.

Cacti grow spines instead of leaves because spines don’t lose water like the leaves of other plants. Cactus Adaptations – Spines (Leaves) #6

Cactus Adaptations – Spines (Leaves) Spines also protect the plant against animals. The cactus basically is saying, "How much pain are you willing to endure to get a drink from me?" #7

White dense spines also help to reflect light away from the cactus stem, which can lower the temperature of the stem. Cactus Adaptations – Spines (Leaves) #9a

Cacti Adaptations - Spines (Leaves) Cacti spines also help keep the plants cooler by casting shade on them. #9b

The spines, ribs, and round shape of some of the cacti combine to make sure that no single part of the plant receives the brunt of the hot sun all day long. Cacti Adaptations - Spines, Ribs, and Shape