Flora of North America species comparison

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Iris douglasiana

Iris pumila
Iris douglasiana

Douglas' iris, mountain iris

dwarf iris
Rhizomes

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

roots fibrous.

freely branching, producing dense clumps, 1–1.5 cm diam.
Stems

1–4-branched, solid, 1.5–7 dm.

absent or not more than 1 cm.
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.

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.
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.

1-flowered, sessile in spathes;

spathes 5–10 cm;

outer darker green than inner, inner closely shielding floral tube.
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.

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.
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 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.
Seeds

dark brown, pyriform, wrinkled.

usually in 2 rows per locule, light brown, subspherical, 3–5 mm diam., wrinkled.
2n

= 40.

= 30, 31, 32, 36.

Iris douglasiana

Iris pumila
Phenology Flowering Apr–Jun. Flowering late Mar–mid May.
Habitat Open woods, sunny slopes and fields Dry, grassy areas
Distribution
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
IL; IN; MI; OH; c Europe; e 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 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.)
Source FNA vol. 26, p. 384. Treatment author: Norlan C. Henderson. FNA vol. 26, p. 375. Treatment author: Norlan C. Henderson.
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. pallida, I. prismatica, I. pseudacorus, 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) Linnaeus: Sp. Pl. 1: 38. (1753)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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