Iris tenuissima, Junction City, Trinity County, California
Range: Northern California foothills around upper end of the Great Central Valley, southern Klamath and Cascade Ranges. 300 to 6,000 feet elevation.
Original material: Pit River Ferry (Lake Shasta), Shasta County, California 1912(?)
Key identifying features:
1. Long floral tube; 1½ to 3 inches
2. Tube abruptly larger in upper, throat-like section, as in the end of an upturned bottle.
3. Long, narrow style crests, usually turned back inward
4. Floral parts slender and easily broken ("tenuissima" = very tenuous)
5. Flowers appear rather flat; petals and sepals spread outward, their edges often ruffled
6. Stigma sharply triangular, nearly tongue-shaped
Flower color: Cream, pale yellow or white, with prominent reddish-brown, lavender or darker yellow veins.
Habitat: Shaded, duff-covered forest floor or small sunny openings in oak/pine woodlands.
Comment: Iris tenuissima seems to replace I. macrosiphon in the foothills north of California's Great Central Valley. In the past, it was sometimes referred to as "yellow I. macrosiphon", but with its throat-like upper floral tube, and long styles and style crests, it appears more closely related to I. chrysophylla.
 Lassen Volcanic Park, Shasta County, California |
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A southeastern race. Populations in California's Plumas, Shasta, Sierra, Butte and Tehama counties have been treated as a distinct recognizable race, and given the name I. tenuissima purdyiformis (= "purdyi - like"). This is the region around Lassen Volcanic National Park where the southern end of the Cascade Range meets the northern tip of the granitic Sierra Nevada mountains. Flower parts are slender, spidery and often ruffled. Several leaves extend upward clasping the stem (without overlapping as in I. purdyi). The style crests are still long and narrow, but not as much as in plants from farther west, the floral tube is less abruptly dilated, and the color is cream-yellow with no or only a few purple veins.