Oreocereus celsianus var. boliviensis is the bolivian variety of Oreocereus celsianus, commonly known as the Old Man of the Andes. These are columnar cacti that are native to the high-altitude regions of South America, including Bolivia and Argentina. Here are some key characteristics and information about this cactus variety:

1. Appearance: Oreocereus celsianus var. boliviensis, like the typical Oreocereus celsianus, is a tall, slender columnar cactus that can reach heights of up to 4 meters (approximately 13 feet) or more. The stem of this cactus is covered in a dense, white woolly substance, giving it a distinctive "old man" or "senile" appearance. This white woolly covering helps protect the cactus from intense sunlight and extreme temperatures in its high-altitude habitat.

2. Growth Habit: These cacti are relatively slow-growing and can take many years to reach their mature height. They typically have multiple ribs along their stems.

3. Flowers: Oreocereus celsianus var. boliviensis produces small, funnel-shaped flowers that are typically pink to purple in color. These flowers often bloom from the sides of the cactus stem.

4. Habitat: This cactus variety is adapted to high-altitude regions in the Andes Mountains of South America. It can withstand cold temperatures and is often found at elevations of 2,000 meters (6,500 feet) or higher.

5. Conservation Status: Some populations of Oreocereus celsianus var. boliviensis may be threatened by habitat destruction and illegal collection. As a result, it is important to protect these cacti in their native habitats and avoid overcollecting them.

6. Cultivation: Oreocereus celsianus var. boliviensis is sometimes grown as an ornamental cactus in succulent collections or gardens. When cultivated, it requires well-draining soil and plenty of sunlight but should be protected from extreme heat. Like most cacti, it is adapted to arid conditions and should be watered sparingly.

7. Legal Protection: In some regions, cactus populations are protected by laws to prevent their removal from the wild and to conserve these unique and slow-growing plants.