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Douglas' iris, mountain iris

sweet iris

Rhizomes

freely branching, forming large colonies, slender, 0.8–0.9 cm diam., covered with remains of old leaves;

roots fibrous.

branching, forming extensive clumps, 1.5–2 cm diam., smooth except for narrow leaf scars that completely encircle rhizome.

Stems

1–4-branched, solid, 1.5–7 dm.

1–3-branched, 6–10 dm.

Leaves

basal with blade yellow-green, occasionally darker green, sometimes flushed pink or red basally, prominently ribbed, linear, 4.5–10 dm × 2 cm, apex acute;

cauline 1–3, reduced.

erect to spreading, blade green (some forms with white or yellow longitudinal stripes), ensiform, 3–6 dm × 3–4 cm, very glaucous, smooth.

Inflorescences/Inflorescence units

(2–)3-flowered, branch units 2–3-flowered;

spathes opposite or separated, divergent, green, sometimes flushed purple basally, lanceolate-acuminate, 6–12 cm × 7–12 mm.

with terminal unit 3-flowered, branch units 2–3-flowered;

distal branches subtended by scarious bracts, lower one to 15 cm, herbaceous, green;

spathes completely silvery white, 2–3.5 cm, scarious.

Flowers

perianth deep red-purple, lavender, gray-blue, cream, or white, with gold signal and blue or purple veins;

floral tube 1.5–2.8 cm, usually widening to bowl shape at base of flower;

sepals oblanceolate to obovate, 5–9 × 1.4–3 cm, base gradually attenuate, apex obtusely rounded;

petals oblanceolate, 4.5–7 × 0.9–1.8 cm, base attenuate to narrow claw;

ovary elliptic-oval, sharply triangular in cross section, 3–4 cm;

style 1.7–3.5 cm;

crests overlapping, subquadrate, 1–2 cm, margins coarsely toothed;

stigmas triangular;

pedicel 2–5 cm.

often very fragrant;

perianth light blue-violet to mauve-purple, one form with blue pigment limited as stipples or stitches along margin and/or along veins, with ground color white on both petals and sepals;

floral tube 1–1.3 cm;

sepals slightly reflexed, obovate, 7.8–8.3 × 5–5.3 cm, with wedge-shaped claw marked with brown veins, beard yellow with white tips;

petals blue-violet, in some forms lighter than sepals, with some brown veining at base and on claw, obovate, 8 × 5 cm;

ovary trigonal, 6-grooved, 1–1.5 cm;

style violet, fading paler along margins, keeled along midrib, 2–2.4 × 1 cm, crests rounded, 1.4 cm, apex acute;

stigmas rounded, margins entire;

pedicel very short, 2–3 mm.

Capsules

sharply triangular in cross section with ridge at each angle, tapering at both ends, remnant of floral tube forming tip at apex, 2.5–5 cm.

borne on ends of stems and branches, oblong, trigonal, 6-grooved, 4–5 × 1.5–2 cm.

Seeds

dark brown, pyriform, wrinkled.

in 2 rows per locule, dark brown, compressed, cubical, wrinkled.

2n

= 40.

= 24.

Iris douglasiana

Iris pallida

Phenology Flowering Apr–Jun. Flowering Apr–mid Jun.
Habitat Open woods, sunny slopes and fields Widely cultivated and often persisting around old dwellings
Distribution
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; GA; IN; MO; Europe [Introduced in North America]
[BONAP county map]
Discussion

R. C. Foster (1937) named several varieties of Iris douglasiana, about which L. W. Lenz (1954) said, “This is a widespread and extremely variable species whose total variability is being increased due to introgressive hybridization between it and other species with which it has come into contact. Well marked and distinct geographic races cannot be detected; however, pronounced variations are to be found within a single population. For these reasons no attempt is made here to segregate taxa within such a polymorphic species.”

Iris douglasiana hybridizes with I. bracteata, I. chrysophylla, I. fernaldii, I. hartwegii, I. innominata, I. macrosiphon, I. munzii, I. purdyi, I. tenax, and I. tenuissima. The natural hybrid between I. douglasiana and I. innominata has been designated as Iris ×thompsonii R. C. Foster and the garden hybrid as Iris ×aureonympha E. H. English.

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

Iris pallida is considered to be one of the parents of I. germanica, to which it contributed blue pigment (delphinin) as well as the recessive white allele responsible for white-flowered forms. It also contributed the recessive distribution-pattern allele that limits the blue pigment to veins and to stipples or larger dots along the margins of the petals and sepals, the plicata pattern so popular in the garden today.

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

Source FNA vol. 26, p. 384. FNA vol. 26, p. 376.
Parent taxa Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Californicae Iridaceae > Iris > subg. Iris
Sibling taxa
I. bracteata, I. brevicaulis, I. chrysophylla, I. cristata, 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. 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. 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. beecheyana, I. douglasiana var. alpha, I. douglasiana var. altissima, I. douglasiana var. beecheyana, I. douglasiana var. bracteata, I. douglasiana var. major, I. douglasiana var. mendocinensis, I. douglasiana var. nuda, I. douglasiana var. oregonensis, I. watsoniana
Name authority Herbert G. A. W. Arnott: in W. J. Hooker and G. A. W. Arnott, Bot. Beechey Voy., 395. (1840) Lamarck: in J. Lamarck et al., Encycl. 3: 294. (1789)
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