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iris de virginie, southern blue flag, Virginia iris

giant blue iris

Rhizomes

many-branched, forming dense clumps, 2–4 cm diam., usually covered with remnants of old leaves;

roots fleshy.

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

Stems

rather weak, often falling over after flowering, solid, usually 1-branched, 5–10 dm.

2–3-branched, solid, 10–15(–20+) dm.

Leaves

basal erect or often flexible, blade gray-green to bright green, buff to purplish basally, with several prominent ribs in mature leaves, linear-ensiform, 6–8 dm × 2.5–3 cm, apex acute.

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.

Inflorescence units

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

spathes compact, often with brown striations, ridged, unequal, outer 3–8 cm, inner 8–14 cm, firm, herbaceous.

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.

Flowers

perianth lavender to violet, rarely white;

floral tube constricted above ovary, 1–2 cm;

sepals spreading and arched, pale blue to purple with darker blue or purple lines, obovate to oval, 4–8.4 × 1.6–4 cm, base abruptly attenuate, claw green in median, bordered by yellow ground with blue or purple lines, yellow extending onto base of limb as finely pubescent signal patch;

petals oblong-lanceolate to oblong-spatulate, 3–7 × 1–3 cm, claw greenish yellow with blue or purplish lines, apex often emarginate;

ovary trigonal, 1.3–3.8 cm;

style inwardly auriculate at convergences, 3–4.5 cm, crests reflexed, 0.7–2 cm;

stigmas unlobed, with prominent triangular tongues, margins entire;

pedicel 2.5–8 cm.

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.

Capsules

ovoid, ellipsoid, or long-cylindric, trigonal or polygonal in cross section, 3–6 × 1–2 cm.

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.

Seeds

in 2 rows per locule, pale brown, usually D-shaped, 5–8 mm, pitted, corky.

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

2n

= 70, 72.

= 44.

Iris virginica

Iris giganticaerulea

Phenology Flowering May–Jun. Flowering Mar–Apr.
Habitat Wetlands, margins of lakes and streams Shallow water or very wet roadside ditches
Distribution
from FNA
AL; AR; DC; FL; GA; IA; IL; IN; KS; KY; LA; MD; MI; MN; MO; MS; NC; NE; NY; OH; OK; PA; SC; TN; TX; VA; WI; WV; ON; QC
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from FNA
AL; LA; MS
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[BONAP county map]
Discussion

Plants of Iris virginica from the southeastern and south-central states having stems 2–3-branched and seldom falling to the ground after flowering, and with capsules long-cylindric have been recognized as var. shrevei.

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

Source FNA vol. 26, p. 390. FNA vol. 26.
Parent taxa Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Laevigatae Iridaceae > Iris > subg. Limniris > sect. Limniris > ser. Hexagonae
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. verna, I. versicolor
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
Synonyms I. caroliniana, I. georgiana, I. shrevei, I. virginica var. shrevei I. elephantina, I. hexagona var. giganticaerulea, I. miraculosa
Name authority Linnaeus: Sp. Pl. 1: 39. (1753) Small: Addisonia 14: 5, plate 451. (1929)
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