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dwarf violet iris

Rocky Mountain iris, western blue flag

Rhizomes

heterogeneous, whitish, cordlike portions 0.1–1.5 dm × 2–4 mm, enlarging to 6–8 mm diam., densely covered with brown, scalelike leaves, roots absent, or torulose with roots borne along entire rhizome.

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

roots fleshy.

Stems

simple, 5–15 cm.

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

Leaves

basal with blade light green, ensiform, 0.3–1.5 dm × 0.3–1.3 cm, enlarging to 3.5 dm, glaucous;

cauline 5–9, sheathing, imbricate, blade light green, obovate, 1.3–5 cm, increasing in length, proximal shortest, membranous, apex acute.

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.

Inflorescences/Inflorescence units

1–2-flowered;

spathes divergent, exposing floral tube, green, lanceolate, 2–2.5 cm, apex acuminate.

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.

Flowers

floral tube pale violet, filiform, 2.5–6.5 cm, expanding somewhat distally to 2.5–4 cm diam.;

sepals widely spreading, blue to violet with yellow or orange longitudinal papillose band at base of blade, obovate, 2–6 × 0.8–2 cm, base gradually attenuate into claw, not crested;

petals erect, arching inward at tip, spatulate, 2–7 × 1–2 cm, base abruptly attenuate into claw;

ovary linear, to 1.3 cm;

styles pale violet, 2.5–4 cm, crests linear-acute, narrow, 0.7 cm;

stigmas rounded, margins entire;

pedicel 1–3 cm, increasing to 25 cm as capsule matures.

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.

Capsules

3-angled with single ridge at each angle, almost hidden in bases of spathes, 1–3.2 × 0.8–1.5 cm, tapering into beak consisting of dried remnant of floral tube.

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

Seeds

dark brown, ribbed, 2.8–3.2 mm, lustrous, with small, fleshy aril basally.

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

2n

= 38.

Iris verna

Iris missouriensis

Phenology Flowering May–Jul.
Habitat Wet meadows, roadside ditches, margins of streams
Elevation 10–3000 m (0–9800 ft)
Distribution
from USDA
se United States
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; ID; MT; NE; NM; NV; OR; SD; UT; WA; WY; AB; BC; n Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

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

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.)

Key
1. Rhizomes 5–15 cm between offshoots; leaf blades 0.3–0.8 cm wide; capsules 1.2–1.8 cm.
var. verna
1. Rhizomes 1.3 cm between offshoots; leaf blades 5–13 cm wide; capsules 2–3.2 cm.
var. smalliana
Source FNA vol. 26, p. 379. FNA vol. 26, p. 388.
Parent taxa Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Vernae Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Longipetalae
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. missouriensis, 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. 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. 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
Subordinate taxa
I. verna var. smalliana, I. verna var. verna
Synonyms Neubeckia verna I. arizonica, I. longipetala var. montana, I. montana, I. pariensis, I. pelogonus, I. tolmieana
Name authority Linnaeus: Sp. Pl. 1: 39. (1753) Nuttall: J. Acad. Nat. Sci. Philadelphia 7: 58. (1834)
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