The evolution of vascular tissue is a key innovation enabling plants to inhabit terrestrial environments. Here, we demonstrate extra-vascular water transport in a giant, prop-rooted monocot from Lord Howe Island. Pandanus forsteri (Pandanaceae) produces gutter-like leaves that capture rainwater, which is then couriered along a network of channels to the tips of aerial roots, where it is stored by absorptive tissue. This passive mechanism of water acquisition, transport, and storage is critical to the growth of aerial prop roots that cannot yet attain water via vascular conduction. This species therefore sheds light on the elaborate means by which plants have evolved to attain water.