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Rocky Mountain iris, western blue flag

Munz's iris

Rhizomes

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

roots fleshy.

freely branching, forming large clumps, slender, 1–1.2 cm diam., covered with remains of old leaves;

roots fibrous.

Stems

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

simple, solid, 6–7 dm.

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 persistent, blade gray-green, green and without pink coloration basally, 6–7 dm × 1.5–2 cm, glaucous, margins not thickened;

cauline 1–2, free from stem for ca. 1/2 length, foliaceous, spreading, blade not inflated.

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.

3(–4)-flowered;

spathes widely separated, sometimes by 9 cm, divergent, unequal, outer 6.5–15 cm × 8–14 mm, inner much shorter.

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 pale powder blue to lavender or violet, often frilled and veined in violet or darker blue;

floral tube funnelform, 0.7–1 cm;

sepals oblong-ovate to broadly oblanceolate, 6.2–9 × 1.8–3.7 cm, base gradually attenuate, apex emarginate;

petals oblong to spatulate, 5–9.5 × 1.2–2.1 cm, base attenuate, apex apiculate;

ovary rounded in cross section, 1.4–3 cm, base gradually attenuate into pedicel, apex abruptly acuminate into floral tube;

style 3 cm, crests reflexed, subquadrate, shallowly lobed, 1.1–2 cm, margins entire or obscurely and shallowly lobed;

stigmas triangular, margins entire;

pedicels of varying lengths, 0.8–4.8 cm on first flower, those of later flowers longer.

Capsules

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

oblong, rounded in cross section, tapering abruptly at either end, to 5 cm.

Seeds

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

brown, D-shaped or irregular, coarsely wrinkled.

2n

= 38.

= 40.

Iris missouriensis

Iris munzii

Phenology Flowering May–Jul. Flowering Apr–May.
Habitat Wet meadows, roadside ditches, margins of streams Partially shaded areas and along stream banks or on moist slopes
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
CA
[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.)

No natural hybrids of Iris munzii are known, but horticultural hybrids have been made with I. bracteata, I. douglasiana, I. hartwegii, I. innominata, and I. macrosiphon. It is known only from Tulare County, California.

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

Source FNA vol. 26, p. 388. FNA vol. 26, p. 387.
Parent taxa Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Longipetalae Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Californicae
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. 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
Synonyms I. arizonica, I. longipetala var. montana, I. montana, I. pariensis, I. pelogonus, I. tolmieana
Name authority Nuttall: J. Acad. Nat. Sci. Philadelphia 7: 58. (1834) R. C. Foster: Iridis Sp. Nov., 2. (1938)
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