(Plant Identification for everyone)

   Marin County  |  Plant Groups

Marin Irises

These four Marin Irises are arranged in order of prominence.  The most common, Douglas Iris, you’ll see in many open and wooded areas.  Ground Iris, although less common, is still widespread and can be recognized since the flower grows close to the ground and has a long tube under the flower.  You’ll be excited when you find Central Coast Iris, with its delicate long lavender and white petals.  And Stinking Iris, the only non-native, you’ll only find on the Mt. Tamalpais side of the reservoirs.

Douglas Iris

Iris douglasiana


Common.  Open hills, wooded areas.


Iris Family



·  Blooms Feb – June

·  Flower cream to purple, about 2.5” across.

·  One to three flowers on a stem, 6” – 18” tall.

·  Leaves narrow and long, with parallel veins. 

·  Leaves underside paler than top.

Douglas Iris

Petals in 3s, with colorful veins.  Color varies quite a bit.

Douglas Iris-2

Wooden seed casing in threes stays on flower after bloom finishes.


Multiple flowers near end of

stem.  Leaves paler underneath. 

Ground Iris

Iris macrosiphon


Sunny grasslands


Iris Family


Only in California



·  Blooms Mar - May

·  Only Marin Iris with a fragrance.

·  Flower about 2.5” across, color is variations on white, yellow or blue.

·  Single flower on each stem, low to the ground.

·  Tube below flower is longer (thus macrosiphon) than Douglas Iris.

·  Long leaves, parallel veins, underside same color as top.

Iris macrosiphon_Ground Iris_Tomales Bay_2005-03-12__WF

Petals in 3s, often with dark


Ground Iris_Iris macrosiphon_China Camp_2009-03-14__KF-__KF

Notice long tube (Perianth Tube) below the flower – 2 or 3 inches.

Iris macrosiphon_Long-tubed Iris__DLS-__DLS

Flowers are low to the ground.  Leaves same color both sides.

Central Coast Iris

Iris longipetala


Open hills and low wet fields.


Iris Family


Only in California



·  Blooms Mar - May

·  Flower with long slender petals.  Outer petals are white with lavender veins, and inner petals are all lavender.

·  Grows in clumps, often in low wet fields.

Iris longipetala 3_Central Coast Iris_Fort Baker_1981-03-07__WF

Outer petals white with lavender veins.  Inner petals all lavender.

Iris longipetala 3_Central Coast Iris_Chileno Valley_1979-04-28__WF

Many narrow petals often clumped together.

Iris longipetala_Central Coast Iris_Chileno Valley_1979-04-28__WF

Plants grow in clumps, often in


Stinking Iris

Iris foetidissima


Only above Phoenix, Alpine, and Lagunitas Lake


Iris Family

Not Native


·  Blooms June - July

·  Flowers dull bluish color

·  Leaves broader than other Marin irises.

·  Bruised leaf smells stinky

·  Prominent red berries last many months after flower.

Notice large seeds forming below flower.

Iris foetidissima_Stinking Iris_Lake Lagunitas_2014-02-14__BHS-2

Red seeds..

Iris foetidissima_Stinking Iris_Lake Lagunitas_2014-02-14__BHS-3

Leaves are broader than other Marin Irises.

© Creative Commons BY NC 3.0.  Contributors (identified by initials) are acknowledged at http://PlantID.Net/Contributors.htm

Reviewed by DLS 6/8/14..  Last Updated 6/24/2014 by BHS. 


Note to botanists – this page uses common vocabulary, sacrificing more precise scientific terms in the interest of general communication.  We hope the loss of precision in wording is, to some extent, made up for by photographs showing key identification points.\


Note to non-botanists – here is a botanical term you might like to know:

·         Perianth – The part of the flower that surrounds the reproductive parts.  In the case of a Ground Iris, the Perianth Tube, which is part of the flower as opposed to the stem, is two to three inches long.