Both! National Garden Bureau explains, “Irises come in three forms, rhizome, bulb or root. The rhizome type iris produce larger flowers and include bearded and beardless type flowers, while the bulb type iris produce smaller flowers are often used in rock gardens or in front row of borders to provide early color in the year. Floral designers use Dutch Iris most often for spring flower designs. Siberian, Louisiana and Japanese iris come in a root form.”