Iris missouriensis
Iris savannarum
Rocky Mountain iris, western blue flag
prairie iris, savanna iris
freely branching, producing large colonies, stout, 2–3 cm diam., clothed with dark remnants of old leaves;
roots fleshy.
greenish, freely branching, forming large, open clumps, 2–2.5 cm diam., fleshy, with fibrous bases of old leaves not covering rhizome but persisting on ringlike scars.
simple or 1–2-branched, solid, 2.5–6 dm.
1-branched, solid, 3–10 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 usually dying back shortly after anthesis, blade bright green, 6–10 dm × 0.8–2 cm, sometimes glaucescent;
cauline with blade elongate, linear-attenuate, 15–20 cm, exceeding flowers.
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.
1–3-flowered, branch units 1–2-flowered;
spathes lanceolate, subequal or unequal, apex acute;
outer 8–10 cm, herbaceous, margins scarious;
inner 6–9 cm, completely 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 blue to blue-violet (white in forma albispiritis);
floral tube funnelform, 1.2–1.5 cm;
sepals blue or pale violet with flecks of white and lines of deeper blue on either side of ridge, spatulate, elliptic to ovate, 7–8 cm, apex acuminate, ridge yellow, linear, extending to about middle of limb, finely pubescent, claw light green, striated, ribbed, 1–1.2 cm;
petals erect or spreading-erect, deep blue, linear to narrowly linear-spatulate, 6–7.5 cm, base abruptly attenuate into claw, claw channeled, green with darker lines, margins pale;
ovary bluntly 3-angled, ridged at each angle and on faces between angles;
style linear-acute, 5–6 cm;
crests ovate, 1–2 cm, margins sharply and irregularly toothed;
stigmas broadly 2-lobed, margins crenate;
pedicel 1.6–2 cm.
almost circular in cross section, with 6 obvious, equidistant ridges, 4–5 × 1.5 cm.
ellipsoid, round in cross section, roundly 6-lobed, with 6 sharp, winglike, equally spaced ridges converging to form stout beak at apex, 6–10 cm, dehiscence loculicidal.
light brown, nearly globular to pyriform, 4–4.5 mm, wrinkled.
in 1 row per locule, brown, circular or uneven, flattened, 8–12 mm diam, very corky.
= 38.
= 44.
Iris missouriensis
Iris savannarum
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.)
Iris savannarum has often been included in I. hexagona, but differs in several ways. The capsules of I. hexagona are more obviously hexagonal, with smooth faces alternating with those that have two rounded lobes, whereas the capsules of I. savannarum are more rounded but with six obvious ridges, almost of winglike proportions. Iris hexagona has yellow-green leaves instead of the brighter green of I. savannarum. The leaves of I. savannarum die back after anthesis, while those of I. hexagona remain green. The flowering period of I. savannarum is almost one month earlier than that of I. hexagona in the area where both are known to grow. The sepals of I. savannarum are more acute at the apex than those of I. hexagona.
Iris savannarum has been hybridized with Iris fulva to produce I. ×cacique (J. Berry) N. C. Henderson.
(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
