Iris tenuis, June 5, Slopes of Mount Hood, Oregon [Almanac 1995]
Three iris representing groups other than the PCNI (series CALIFORNICAE) are old residents of the western United States. A fourth is a more recent garden escapee - sometimes found in long abandoned rural homesites.
1. The Clackamas Iris, Iris tenuis, is the only representative of the CRESTED (or "Evansia") irises living in the western USA. It grows wild along the Clackamas and Molalla rivers in Oregon, widely separated from other relatives in the group. In some areas near Mount Hood, it covers nearly every sunny inch of ground.
2. Western Blue Flag, Iris missouriensis, (series LONGIPETALAE) ranges widely at higher elevations on the eastern side of the Cascade and Sierra Nevada mountains from southern Canada to northern Mexico, and east to the Dakotas. It graces alpine meadows and pastures with ground water near the surface. The three sepals (falls) often all fold down sharply, as if to entice potential pollinators flying in close to the ground from any angle. Grazing livestock avoid the pungent, bitter-tasting leaves, so it thrives in grasslands to the point that cattlemen sometimes consider it a pest.
3. At lower elevations in the California coastal range, Iris longipetala (series LONGIPETALAE) sometimes lives together with various members of the Pacific Coast native iris. It prefers open, sunny, moist meadows, and can usually be distinguished at a glance by the grey-green cast of its leaves, well-defined lavender veins on the petals, and single, mostly unbranched stalks bearing three to six flowers in a head-like bunch.
Iris longipetala might be a regional strain of Iris missouriensis that became isolated during the Ice Ages and over time adapted to a coastal Mediterranian climate environment. There are several differences: stems tend to be taller (30-60 cm, vs. 20-50 cm for I. missouriensis), with more flowers on each stem (3 to 6 vs. 1-3 for I. missouriensis); and the lower bracts seldom dry out into a parchment-like skirt below the flower head as in I. missouriensis. Nevertheless, one botanist reported that after a few generations to adjust, lowland I. longipetala plants moved to a garden in the Sierra Nevada mountains looked and behaved like I. missouriensis. The possibility that a PCN iris might have a place in the I. longipetala ancestory has yet to be tested.
4. The yellow flag iris, Iris pseudacorus (series LAEVIGATAE) is an attractive marsh dweller that easily escapes from gardens. White flowered colonies are sometimes seen. This Mediterranean region iris is used in wetland landscaping, and has become naturalized in much of temperate North America. It sometimes marks the place where an old homestead long ago disappeared.
