Matt Kirk of the Kauai Nature School on the walk we took with him on Kauai.
Another much tastier flower we tried was Jamaican vervain (Stachtarpheta sp.), also known as porterweed or rat's tail. It is native to tropical Central America, and there are several species found in Hawaii. It grows along roadsides and disturbed areas at lower elevations, we found plenty on seaside cliffs. The leaves are opposite and toothed, with a rough surface. The plant produces a long, spindly flower spike about 12" above the leaves, and there are a few tubular, 5-petaled, blue or purple flowers blooming along this flower spike at a time. This flower tastes like shiitake mushrooms, and Matt explained to us that the flowers have a slight sedative effect when eaten in quantity.