Cereus peruvianus 'Monstruosus,' often referred to as the monstrose apple cactus or the monster cactus, is a unique and intriguing cactus plant known for its unusual, contorted, and irregular growth patterns.  

1. Growth Habit: Cereus peruvianus 'Monstruosus' is a slow-growing cactus that typically forms multiple tall, columnar stems. What makes it distinct is its irregular, contorted, and twisted growth, often resembling a cluster of tangled arms or a monstrous, gnarled tree-like structure.

2. Stems: The stems of this cactus are usually bluish-green to gray-green and have a ribbed or grooved texture. They can reach heights of 10 to 30 feet (3 to 9 meters) in their natural habitat, although they may remain shorter when grown in containers.

3. Areoles: The areoles (small, raised areas on the cactus where spines and flowers emerge) of 'Monstruosus' are spaced irregularly along the stems, contributing to its unique appearance.

4. Spines: Unlike some other cacti, 'Monstruosus' often has very short or almost non-existent spines. Some individuals may produce tiny, inconspicuous spines on their areoles, but they are generally not a prominent feature.

5. Flowers: This cactus produces large, white or cream-colored, nocturnal flowers that are around 6 inches (15 cm) in diameter. The flowers are fragrant and bloom during the summer months. They are typically followed by the development of small, spherical fruits.

Cultivation:

1. Climate: Cereus peruvianus 'Monstruosus' is native to arid regions of South America and is well-suited for USDA hardiness zones 9b to 11. It thrives in warm, dry climates and is sensitive to frost and freezing temperatures.

2. Sunlight: Provide your 'Monstruosus' cactus with full sunlight for most of the day. These cacti require plenty of direct sunlight to grow and develop their characteristic form.

3. Soil: Plant your cactus in well-draining, sandy, or cactus-specific potting mix. Good drainage is essential to prevent root rot.

4. Container vs. Ground: 'Monstruosus' can be grown in containers or directly in the ground, depending on your climate and space. In areas with cold winters, container cultivation allows for easier protection during frost.

5. Watering: Water sparingly, allowing the soil to dry out completely between waterings. Overwatering can lead to root rot, which is a common issue with cacti. Reduce watering during the winter when the plant is dormant.

6. Fertilizing: Feed your cactus with a balanced, water-soluble cactus fertilizer during the growing season (spring and summer). Dilute the fertilizer to half or quarter strength to prevent overfeeding.

7. Container Size: If growing in a container, choose a pot that is slightly larger than the root ball. Repotting every few years may be necessary to accommodate growth.

8. Pruning: Pruning is generally not required for 'Monstruosus' cacti. However, you can remove any dead or damaged stems as needed to maintain the plant's appearance.

9. Pests and Diseases: 'Monstruosus' cacti are relatively resistant to pests and diseases. Keep an eye out for common cactus pests like mealybugs and scale insects, and address them promptly if they appear.

10. Protection from Cold: If you live in an area with occasional frost, provide protection for your cactus during cold spells by covering it with frost cloth or moving it indoors.

Cereus peruvianus 'Monstruosus' is a fascinating and visually striking cactus that can be an attractive addition to your landscape or indoor collection. Its unique growth pattern makes it a conversation piece, and with the right care, it can thrive and continue to develop its peculiar form over time.

IMPORTANT: Picture show an adult plant not for sale, the plant for sale is of the dimension described.