Iris missouriensis
Iris tenax
Rocky Mountain iris, western blue flag
Oregon flag, Oregon iris, tough-leaf iris
freely branching, producing large colonies, stout, 2–3 cm diam., clothed with dark remnants of old leaves;
roots fleshy.
many-branched, not creeping, forming dense clumps, slender, 0.3–0.8 cm diam.;
roots fibrous.
simple or 1–2-branched, solid, 2.5–6 dm.
simple, somewhat angular, solid, 1.5–2.7 dm.
basal with blade light green, often white basally, not prominently veined, linear, 4.5–6 dm × 0.3–1.2 cm, glaucous, apex acute;
cauline 2–3, often shed with spent stem, similar to basal leaves, distal may subtend branch.
basal somewhat lax, overtopping stem, blade light green, paling to pink or straw color basally, finely ribbed, linear-acute to linear, ensiform, 4.5 dm × 0.5 cm, margins not thickened;
cauline 1–3, sheathing for 1/2 length then spreading, foliaceous, blade linear-lanceolate, not inflated, narrow, reduced, to 15 cm.
with terminal and lateral units (when present) (1–)2–3-flowered;
spathes subopposite to distant, to as much as 3–7.5 cm apart, lanceolate or ovate, keeled, outer usually shorter, 3.5–4 cm, inner 5.5–7 cm, scarious with herbaceous areas basally and along keel, apex acuminate.
1–2-flowered;
spathes distant basally by 3 cm in some cases, keeled, linear-lanceolate to lanceolate-acuminate, 5–7 cm × 2–4 mm, unequal, outer longer than inner, herbaceous, margins scarious.
perianth blue to lavender to white, veined deeper violet;
floral tube green with purple veins in line with midrib of petals, funnelform, constricted above ovary, 0.5–1.2 cm;
sepals deeply veined lilac-purple, with yellow-white signal at base of limb, claw yellowish white, veined and dotted with purple, obovate, 3.7–7 × 1.2–3.2 cm;
petals slightly divergent, oblanceolate to spatulate, 3.6–7 × 0.5–1.2 cm, base gradually attenuate, apex acuminate or rarely emarginate;
ovary trigonal with 6 shallow ridges, 1–2 cm;
style 2.4–4 cm, crests quadrate, 0.7–1.4 cm, margins irregularly toothed;
stigmas 2-lobed, margins entire;
pedicel slender, 1–6 cm at anthesis, increasing to 7.5–8 cm at maturity.
perianth color variable, purple, pink, lavender, cream, yellow, or rarely white;
floral tube funnelform, 0.6–2 cm;
sepals veined with color of limb, obovate, 5.8–6 × 1.6–2 cm, base gradually attenuate into white claw with slight yellow ridge, apex emarginate to bluntly rounded;
petals same color as sepals, not prominently veined, lanceolate to oblanceolate, 5 × 1 cm;
ovary 1–2 cm, slightly wider distally, base very gradually attenuate;
style 2.2–3.2 cm, crests subquadrate, 8–12 mm, margins crenate or incised;
stigmas triangular, margins entire;
pedicel 1–5 cm, longer in second flower (when present) than in first.
almost circular in cross section, with 6 obvious, equidistant ridges, 4–5 × 1.5 cm.
oblong, triangular in cross section, prominently ribbed, beaked, 3–5 cm.
light brown, nearly globular to pyriform, 4–4.5 mm, wrinkled.
brown, D-shaped to irregular, wrinkled.
= 38.
Iris missouriensis
Iris tenax
The ecological range of Iris missouriensis is probably more varied than that of any other North American species of the genus, extending from almost sea level in southern California to 3000 m in Montana and Wyoming. There is correspondingly wide variation in a number of characters, which has caused much confusion as to taxonomic circumscription. Homer Metcalf (pers. comm.) made a detailed study of this species. The basic requirement for its success seems to be an extremely wet area before flowering and then almost desertlike conditions for the rest of the summer.
In large populations, sometimes covering hundreds of acres, Iris missouriensis may be found with either simple or branched stems, leaves from 4 mm to more than 1 cm wide, shorter than the stem or longer, only one flower to as many as three on a stem, and colors from deep blue to almost pure white. A single plant found on the Pariah Plateau in Kane County, Utah, with leaves only 3–4 mm wide and a single flower stem only 4 cm long, which meant that the flower was at almost ground level, was named Iris pariensis. No other such specimen has been located, and this entity must be considered as just an aberrant form that was due to the desertlike conditions in which it was growing.
Iris missouriensis is known to hybridize with I. longipetala.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Plants described as subsp. klamathensis differ from others of the species in having floral tubes 11–20 mm instead of 6–10 mm, style crests somewhat longer and narrower, and flower color and markings more like those of Iris bracteata or I. innominata. The latter species has an even longer floral tube, 15–30 mm, which could be evidence of introgression. Hybrids are known to occur in the area common to both species, in Douglas County, Oregon.
Iris tenax hybridizes with I. bracteata, I. chrysophylla, I. douglasiana, I. hartwegii, I. innominata, I. macrosiphon, I. purdyi, and I. tenuissima.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
OR
WA
Flora NW
PNW Herbaria
SW CO Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
