The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Rocky Mountain iris, western blue flag

beach-head iris

Rhizomes

freely branching, producing large colonies, stout, 2–3 cm diam., clothed with dark remnants of old leaves;

roots fleshy.

many-branched, producing dense clumps, 3–6 × 1.5–2 cm, covered with remnants of old leaves.

Stems

simple or 1–2-branched, solid, 2.5–6 dm.

1–2-branched, 1.5–9 dm, exceeding leaves;

branches 1.25–1.5 dm proximal to terminal, but bearing flowers on nearly the same level.

Leaves

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 with blade green with purple tinge basally, prominently ribbed, ensiform, 0.2–0.45 dm × 1–2 cm, ± glaucous distally;

cauline subtending each lateral branch, blade reduced, 0.5–1.5 dm.

Inflorescences/Inflorescence units

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.

2–3-flowered, lateral units usually 2-flowered;

spathes green flushed with purple, foliaceous, ovate-lanceolate, 2.5–4.5 cm × 5–7 mm, unequal, inner longer than outer, sometimes scarious.

Flowers

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 dark blue-violet to red-purple with darker veins;

floral tube ca. 0.7 cm;

sepals 4–6 × 3–5 cm, glabrous, base abruptly attenuate to broad claw with undulate margins;

petals much reduced, 1–2 × 0.3–0.4 cm, widest basally, mostly hidden by bases of outer sepals, apex acuminate, with 3–8 mm bristle;

ovary conspicuously 3-angled, inflated at anthesis, 1.3 cm;

style 2.5 cm, crests overlapping, subquadrate, 0.7 cm, margins incised;

stigmas semicircular, margins entire;

pedicel 2.5–4.5 cm, ± equaling spathes.

Capsules

almost circular in cross section, with 6 obvious, equidistant ridges, 4–5 × 1.5 cm.

roundly trigonal, 2.5 × 1.3–1.5 cm.

Seeds

light brown, nearly globular to pyriform, 4–4.5 mm, wrinkled.

in 2 rows per locule, light brown, with prominent raphe, D-shaped, 2–3 mm, very smooth.

2n

= 38.

= 34, 36, 38.

Iris missouriensis

Iris setosa

Phenology Flowering May–Jul. Flowering Jul–Aug.
Habitat Wet meadows, roadside ditches, margins of streams Boggy meadows, shores, and dunes
Elevation 10–3000 m (0–9800 ft)
Distribution
from FNA
AZ; CA; CO; ID; MT; NE; NM; NV; OR; SD; UT; WA; WY; AB; BC; n Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; BC; YT; e coastal Asia to Japan
[WildflowerSearch map]
[BONAP county map]
Discussion

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 setosa was originally described from Siberia; whether our populations are an extension from or were formerly continuous with the Asian ones is not known. Two varieties from Japan, var. hondoensis Honda and var. nasuensis Hara, with 2n = 54 may be triploids.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 26, p. 388. FNA vol. 26, p. 380.
Parent taxa Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Longipetalae Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Tripetalae
Sibling taxa
I. bracteata, I. brevicaulis, I. chrysophylla, I. cristata, I. douglasiana, I. fernaldii, I. fulva, I. germanica, I. giganticaerulea, I. hartwegii, I. hexagona, I. hookeri, I. innominata, I. lacustris, I. longipetala, I. macrosiphon, I. munzii, I. orientalis, I. pallida, I. prismatica, I. pseudacorus, I. pumila, I. purdyi, I. savannarum, I. setosa, I. sibirica, I. tenax, I. tenuis, I. tenuissima, I. tridentata, I. verna, I. versicolor, I. virginica
I. bracteata, I. brevicaulis, I. chrysophylla, I. cristata, I. douglasiana, I. fernaldii, I. fulva, I. germanica, I. giganticaerulea, I. hartwegii, I. hexagona, I. hookeri, I. innominata, I. lacustris, I. longipetala, I. macrosiphon, I. missouriensis, I. munzii, I. orientalis, I. pallida, I. prismatica, I. pseudacorus, I. pumila, I. purdyi, I. savannarum, I. sibirica, I. tenax, I. tenuis, I. tenuissima, I. tridentata, I. verna, I. versicolor, I. virginica
Synonyms I. arizonica, I. longipetala var. montana, I. montana, I. pariensis, I. pelogonus, I. tolmieana I. arctica
Name authority Nuttall: J. Acad. Nat. Sci. Philadelphia 7: 58. (1834) Pallas ex Link: Jahrb. Gewächsk. 1(3): 71. (1820)
Web links