Iris missouriensis
Iris pumila
Rocky Mountain iris, western blue flag
dwarf iris
freely branching, producing large colonies, stout, 2–3 cm diam., clothed with dark remnants of old leaves;
roots fleshy.
freely branching, producing dense clumps, 1–1.5 cm diam.
simple or 1–2-branched, solid, 2.5–6 dm.
absent or not more than 1 cm.
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.
ascending-spreading;
blade grayish green, ensiform or slightly falcate, 8–10 cm × 6–15 mm at anthesis, increasing to 15–20 cm in length on innovations after flowering, dying back in autumn, new growth only in spring, glaucous.
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-flowered, sessile in spathes;
spathes 5–10 cm;
outer darker green than inner, inner closely shielding floral tube.
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.
floral tube with 3 purple stripes in line with midrib of petals, slender, 6–10 cm × 2–3 mm, lifting expanded portion of flower out of spathes;
sepals yellow, blue, or purple, with yellowish or bluish beard, often with contrasting spot around beard at base of limb, 4–5 × 1.2–2 cm;
petals with darker veins near base, rounded-ovate, broader than sepals, 4–5 × 2.2–2.7 cm, narrowing abruptly to brown-veined claw, apex emarginate;
ovary rounded-trigonal, ca. 1 cm × 4–5 mm;
style crests triangular, margins serrate distally;
stigmas rounded on distal margin, margins entire;
pedicel absent.
almost circular in cross section, with 6 obvious, equidistant ridges, 4–5 × 1.5 cm.
borne on tips of rhizomes at ground level or slightly below, rounded-trigonal, with short portion of dried floral tube forming tip, smooth, 2–3.5 × 1.5–2 cm, dehiscing while green.
light brown, nearly globular to pyriform, 4–4.5 mm, wrinkled.
usually in 2 rows per locule, light brown, subspherical, 3–5 mm diam., wrinkled.
= 38.
= 30, 31, 32, 36.
Iris missouriensis
Iris pumila
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 pumila has been shown to be a natural amphidiploid hybrid between I. pseudopumila Boissier & Heldreich and I. attica Tineo, both 2n = 16. Like many other such hybrids, its range of variability is so extensive that many of its forms have been given specific names. In spite of the variability in color and size, it is now recognized as a distinct species. During the past 50 years, it has been crossed repeatedly with several other species, including I. germanica and its mixed progeny, and this has introduced patterns from the tall-bearded iris into the dwarfs, and vice versa. The ranges of flowering season and plant height are now almost continuous from one extreme to the other, and intermediate groups are now recognized.
Iris pumila is widely grown in gardens and often persists for years after cultivation around old dwellings and along roadsides. It is thus extremely difficult to document and map its spontaneous occurrence. Although most, if not all, of the modern dwarf irises are of hybrid parentage, a number of herbarium specimens from the nineteenth century seem to represent wild forms of I. pumila.
(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
IL Wildflowers
MI Flora
