The weight of the developing plant causes the stalk to bend over and touch the ground, where the plantlet will take root.
This is where the common name "Walking Iris" comes from. The plants "walk" across the landscape (very slowly). The long narrow leaves are arranged in a fan shape, typical of other members of the Iris family. They are thin and droopy, giving mass plantings a soft billowy texture. There is a related species with yellow flowers that has a more upright habit.
Neomarica will grow in mostly sun to full shade. USDA Zones 8 to 11 (native to Central and South America). The higher the zone you're in, the more shade you should give them. Plants generally grow about 18" to 2 feet tall. They make a nice evergreen groundcover under small trees where they'll get a little shade.