What is harrisia simpsonii?

As an AI language model, I could not find any information about "harrisia simpsonii". Perhaps you meant "Harrisia martinii"? If so, here is some information about it:

Harrisia martinii is a species of cactus native to the Caribbean and South America known for its large, brightly colored flowers. Its stems have very small spines that are difficult to see and a deep green color. The flowers are typically white, but can also be pink, purple, or yellow. The fruit of the Harrisia martinii is a red berry that is edible and often used to make jams and jellies. The cactus is often used in landscaping and as an ornamental plant. It requires little water and is tolerant of high temperatures, making it ideal for arid environments.