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giant blue iris

slender blue iris

Rhizomes

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

superficial or only slightly buried in peaty soil, cordlike portions usually 1-branched, 40 cm × 2–5 mm, bearing scalelike leaves at nodes;

nodal roots absent.

Stems

2–3-branched, solid, 10–15(–20+) dm.

simple or 1–2-branched, 3–8 dm.

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 slightly ribbed, 3–6 dm × 0.2–0.5 cm;

cauline 1–4, erect.

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.

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

spathes pale brown, narrowly lanceolate, 2–4 cm, scarious or partially membranaceous.

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 pale blue or blue-violet;

floral tube 0.2–0.3 cm;

sepals pale violet, veined deep violet basally, ovate, 4–5 × 1.3–2 cm, base abruptly attenuate;

petals lavender, oblanceolate, 3.5–4.5 × 0.7–1.5 cm;

ovary trigonal, sharply angled;

style arched, narrow, 2–3 cm, crests divergent, quadrate, 0.5–0.7 cm, margins serrate;

stigmas sharply triangular;

pedicel somewhat flattened, 3–7 cm, exserted from spathe.

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.

sharply 3-angled, almost winged, 3–4 × 1.2–1.4 cm, concave faces 6–14 mm wide.

Seeds

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

in 1 row per locule, buff to dark brown, pyriform, with convex sides, 3–4 mm, smooth.

2n

= 44.

= 42.

Iris giganticaerulea

Iris prismatica

Phenology Flowering Mar–Apr. Flowering Apr–Jul.
Habitat Shallow water or very wet roadside ditches Swampy, peaty soil
Distribution
from FNA
AL; LA; MS
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; CT; DE; GA; KY; MA; MD; ME; NC; NH; NJ; NY; RI; SC; TN; VA
[WildflowerSearch map]
[BONAP county map]
Source FNA vol. 26. FNA vol. 26, p. 395.
Parent taxa Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Hexagonae Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Prisimaticae
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. 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. elephantina, I. hexagona var. giganticaerulea, I. miraculosa
Name authority Small: Addisonia 14: 5, plate 451. (1929) Pursh: Fl. Amer. Sept. 1: 30. (1814)
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