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giant blue iris

beach-head iris

Rhizomes

green, extensively branched, forming large clumps, 2–4 cm diam., with pale leaf scars.

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

Stems

2–3-branched, solid, 10–15(–20+) 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 4–6, erect, blade bright green, ensiform, 10–13 dm × 2–3 cm, apex slightly curved;

cauline with blade foliaceous, appearing as elongated spathe, 5–6.5 dm × 2–3 cm, not exceeding flowers.

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.

Inflorescence units

2–3-flowered, branch units 1–2-flowered;

spathes tightly enclosing ovary and pedicel, 15–20 cm, subequal;

outer narrowly lanceolate, keeled, margins pale, narrow, inner margins translucent, broad, scarious.

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 or blue-purple;

floral tube tubular-prismatic, 9-ribbed and -grooved, 4–5 cm;

sepals blue or blue-purple with white streaks surrounding signal, oval to orbicular-oval, 9.5–11 × 4–5 cm, base abruptly attenuate into claw, apex obtusely angled, signal with raised, yellow, pubescent central ridge, claw green, striate, 4–4.5 × 1–1.2 cm;

petals erect or spreading-erect, spatulate, 7–8.5 × 2–3 cm, base cuneate, apex emarginate;

ovary bluntly 6-angled, 4–4.5 cm;

style blue-violet, keeled, 3.5–4 cm, raised above sepals, crests recurved, 1.5–2 cm, margins sharply and irregularly serrate;

stigmas 2-lobed with 2 triangular teeth;

pedicel columnar, 3.5–5 cm.

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

drooping, bright green, ellipsoid, hexagonal in cross section, with 6 broad, rounded lobes, 8–10 × 3 cm, indehiscent;

after anthesis, flower stem elongates, arching downward to push capsule into water, where walls are broken down and as funiculus is broken, seed rises to surface.

roundly trigonal, 2.5 × 1.3–1.5 cm.

Seeds

in 2 rows per locule, brown, D-shaped, 8–10 mm wide, very corky.

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

2n

= 44.

= 34, 36, 38.

Iris giganticaerulea

Iris setosa

Phenology Flowering Mar–Apr. Flowering Jul–Aug.
Habitat Shallow water or very wet roadside ditches Boggy meadows, shores, and dunes
Distribution
from FNA
AL; LA; MS
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; BC; YT; e coastal Asia to Japan
[WildflowerSearch map]
[BONAP county map]
Discussion

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. FNA vol. 26, p. 380.
Parent taxa Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Hexagonae 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. 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. pumila, I. purdyi, I. savannarum, I. sibirica, I. tenax, I. tenuis, I. tenuissima, I. tridentata, I. verna, I. versicolor, I. virginica
Synonyms I. elephantina, I. hexagona var. giganticaerulea, I. miraculosa I. arctica
Name authority Small: Addisonia 14: 5, plate 451. (1929) Pallas ex Link: Jahrb. Gewächsk. 1(3): 71. (1820)
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