Succulents in the Desert

These plants have thick leaves that can adapt to dry climate like the desert. At the Arboretum, there area variety of cactus plants. Some have large, juicy leaves with small needles on them and are shrub-like. Some have narrower branches that grow tall. Some are skinny and short. Some have red fruits that are edible! These cactus plants have modified parts that help them retain water and survive in the hot dessert. Can you tell what those modified parts are?