See Show Calender


■ (SPEC) Iris thompsonii R. C. Foster

1937, Botanical author Robert C. Foster

Iris thompsonii R. C. Foster (Robert C. Foster, 1937). Series Californicae . Flower color is typically purple, but varies among other colors, including white, cream, gray, blue, red and lavender. The perianth tube is longer than in I. douglasiana or I. innominata . Plants are small, evergreen, with narrow leaves. There are one to two flowers per stem.

Long thought to be a natural hybrid between Iris douglasiana and Iris innominata, this purple flowered species was recognized as a separate species initally by R.C. Foster, then subsumed into Iris innominata as a purple-flowered form by L. Lenz. In 1990, Wilson et al completed chromatography studies on all three species and concluded it is a valid species in on its own.

I. thompsonii is found south of Powers, Oregon in Coos County, southward into northern Del Norte County, California. It grows on open, lightly wooded sites, with sunnier aspect than preferred by I. innominata, and is well inland from the coastal areas preferred by I. douglasiana. Soil preference appears to be transitional between serpentines and non-serpentine soils in this region.

See below:
Iris thompsonii-1a.jpgIris thompsonii-2a.jpgIris thompsonii-3a.jpgthompsonii4.jpg


Foster in Rhodora 1937
Wilson et al, 1990. Madrono 37:113.



Chromosome counts





No hybrids registered ----

Distribution and Cultivation

Distribution: The distribution of the species gives clues as to its cultural requirements, although plants in cultivation can often tolerate a wider range of variables:
The species is found in the following region:

Bonap's North American Plant Atlas shows the following map reproduced by permission of Kartesz, J.T., The Biota of North America Program (BONAP). 2015. Taxonomic Data Center. ( Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)]


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Your Observations Are Valued. Please make note of bud count, branching, purple based foliage and bloom time, etc. Because these are affected by climate, note date, year and geographic location and write these and other comments in the comment box below.


-- Main.RPries - 2010-02-23
I Attachment Action Size Date Who Comment
Iris_thompsonii-1a.jpgjpg Iris_thompsonii-1a.jpg manage 81 K 08 Jun 2011 - 21:31 Main.ksayce Iris_thompsonii
Iris_thompsonii-2a.jpgjpg Iris_thompsonii-2a.jpg manage 81 K 08 Jun 2011 - 21:32 Main.ksayce Iris_thompsonii
Iris_thompsonii-3a.jpgjpg Iris_thompsonii-3a.jpg manage 74 K 08 Jun 2011 - 21:32 Main.ksayce Iris_thompsonii
thompsonii4.jpgjpg thompsonii4.jpg manage 76 K 19 Sep 2013 - 16:53 UnknownUser Photo by Matilija Nursery
Topic revision: r9 - 22 Jun 2016, BobPries
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