Tough-leaf iris (Oregon iris) –Iris tenax
Range: Common and widespread in most of western Oregon and southwest Washington west of the Cascade Mountains, north to the southern foothills of the Olympic Mountains. There is a small separate population in northern California’s Klamath Mountains.
Original material: Seeds sent to England by explorer-naturalist David Douglas, named in 1825 by the British botanist John Lindley, from David Douglas’ notes that local Indians used the tough (“tenax”) leaf fibers as strong cordage to make rope, snares and nets.
Key identifying features:
- Floral tube between ovary and petals is stout and very short (about ¼ inch) .
- Narrow spathes separate, leaving the ovary exposed; lower spathe often set off from stalk at a sharp angle.
- Style crests are short and rounded.
- Stalks usually bear a single flower, occasionally two.
- Plants form dense, compact clumps, with narrow, light green leaves.
Flower color: Wide color range from purple and lavender (near the Cascades), maroon or pink (southwest Washington and northwest Oregon), and pale blue to yellow, cream and white.
Habitat: Open or lightly shaded sites in open oak to mixed species woodlands; unusual in coniferous forests except along edges or where logging has opened up the canopy.
Comments: This Pacific Coast native iris most deserves a common name of “rainbow iris”. Plants showing a wide range of colors can sometimes be found on a single small hillside. Before its extensive color gamut was well recognized, a yellow-flowered variety from the region of Henry Hagg Lake in northern Oregon was described as a separate species –Iris gormanii.
Wild tough-leaf iris forms large, attractive clumps. The species’ cold hardiness could prove useful to hybridizers trying to develop attractive Pacifica strains that grow more easily in cooler regions elsewhere. Where their ranges overlap,I. tenax produces natural hybrids withI. douglasiana, I. chrysophylla,I. innominata, and in California probably withIris tenuissima.
California’s “Orleans Iris” comprises a small, isolated population along the Klamath River near the town of Orleans in Humboldt County. It was described in 1958 as a distinct subspecies –I. tenax klamathensis. The funnel-shaped floral tube is longer (around ½ to ¾ inch), flower color is limited to pale cream or light yellow with a yellow eye spot on the petals and reddish-brown veins, and it lives in more shaded habitats than theI. tenax populations farther north.
