Marin’s beautiful irises

Can you identify the two common irises of Marin County? Douglas iris (Iris douglasiana) and ground iris (Iris macrosiphon) brighten our spring wildflower walks.

Douglas iris has two cream, blue, lavender or purple flowers per branch. The tube at the lower part of the flower is less than 30 millimeters.

Ground iris, sometimes called Marin iris, has a tube that’s greater than 30 millimeters — hence the name “macrosiphon.” The flowers can be cream, yellow, lavender or purple.

Looking at the leaves is another way to distinguish one species from the other. The leaves of ground irises are narrow; the leaves of Douglas irises are wider. Looking at both sides of a leaf is probably the easiest way to make an identification. Douglas iris has leaves that are shiny above and dull on the opposite side. Ground iris has leaves that appear the same on both sides.

— katie martin, UC Marin Master Gardeners