Preformed root initials develop naturally on stems while they are still attached to the parent plants. Good examples of preformed roots can be seen on many monocot species as the brace roots formed to support upright stems.
They are also the roots formed on vines that allow them to climb and attach to upright surfaces.
Brace roots of screw pine (Pandanus)
Aerial roots of poison ivy (Toxicodendron)
