These plants have vessels in their xylem. Most of the species are in the genus Ephedra and have jointed stems and leaves that are nothing more than scales. Sometimes the plants in this genus are called joint firs, as they look like jointed sticks. The plants in this subdivision are adapted to unusually dry environments. They produce tiny leaves in groups of twos and threes that turn brown as soon as they appear. Male and female strobili may occur on the same plant.