The word basil is related to basileios, from the Greek word for king. Basilicum is also the root word for basilica, the name for the cross-shaped floor plans of church buildings. This cross floor plan is at the heart of Catholic Church architecture. The long portion of the cross is the center aisle people walk down to receive the Eucharist at communion. The practice of strewing branches of basil before church communion rails made this plant known as the Holy Communion plant.