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Iridaceae family

Seashore Iris Iris spuria

Also known as: Blue Iris

Seashore Iris is an introduced perennial herb, found in the lower 48 states. It grows to 1.4 ft.

More about this plant

Iris spuria, or blue flag, is a species of the genus Iris, part of the subgenus Limniris and the series Spuriae. It is a rhizomatous perennial plant, from Europe, Asia and Africa. It has purple or lilac flowers, and slender, elongated leaves. It is widely cultivated as an ornamental plant in temperate regions and hybridized for use in the garden. It has several subspecies; Iris spuria subsp. carthaliniae B.Mathew, Iris spuria subsp. demetrii B.Mathew, Iris spuria subsp. maritima (Dykes) P.Fourn. and Iris spuria subsp. musulmanica (Fomin) Takht. It used to have 3 other subspecies, which have now been re-classified as separate species; Iris spuria subsp. halophila, Iris spuria ssp. sogdiana and Iris spuria subsp. notha . It has many common names including 'blue iris', 'spurious iris' and 'bastard iris'. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Hardiness
≥ zone 7 derived from its U.S. range
Size & form
Sources · Size & form
TRY Plant Trait Database (CC BY 4.0) — Height · Foliage
USDA PLANTS — Lifespan
Height
1.4 ft
Lifespan
Perennial
Foliage
Broadleaf
In the garden
Herb layer — Sits in the herb of a layered food forest or polyculture.Open guide →
Chop-and-drop biomass — Soft, low-density wood is quick-growing and easy to cut back — coppice it and drop the trimmings in place as mulch.Open guide →
derived roles
Species characteristics from USDA PLANTS (public domain) + TRY (CC BY) — general guidance, not a guarantee for your exact site. Deer "browsing" is documented palatability, not a deer-proof claim.

Wildlife & pollinators

How pollinator value is scored →
❧ Caterpillar hosts ~16 caterpillar species

Iris supports ~16 caterpillar species.

Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a moderate genus.

Recorded feeding on Iris in North America, including:

Amphipoea keiferi · owlet moth Celaena reniformis · owlet moth Ctenucha virginica · Virginia Ctenucha Endothenia hebesana · Verbena Bud Moth Endothenia rubipunctana · leafroller moth Hydraecia micacea · Rosy Rustic
+ 8 more species →
Lophocampa ingens · tiger moth Lymantria dispar · Gypsy Moth Macronoctua onusta · Iris Borer Moodna ostrinella · Darker Moodna Moth Orgyia leucostigma · White-Marked Tussock Moth Papaipema cataphracta · Burdock Borer Papaipema nebris · Stalk Borer Sparganothis pilleriana · leafroller moth
Keystone count (genus-level) from Warren II 2026 (CC0) · Tallamy host-use records. Named species (a documented Nearctic sample, not exhaustive) from NHM HOSTS (CC0).
✦ Bees 1 bee visitor

1 native & managed bee species is documented visiting Seashore Iris :

Bombus sylvestris · bumble bee
Visitor records (observations, not exhaustive) from Noori et al. 2026 (CC BY 4.0) · GloBI →
Species thumbnails re-hosted from iNaturalist — Creative Commons, credited per image (hover for credit). Click any species to see it on iNaturalist. Not exhaustive; many taxa have no openly-licensed photo yet.
How we know this (2) Methods & honest limits
Leaf build Direct fact

We read each species’ measured specific leaf area (leaf area per unit dry weight) from the Global Spectrum dataset and band it: thin & fast (high SLA), medium, or thick & tough (low SLA). The global median is about 10 mm²/mg.

Honest limits: A species-mean from pooled measurements — individual plants vary with light and site. A broad strategy signal, not a precise per-plant figure.

Díaz, S. et al. (2022) The global spectrum of plant form and function: enhanced species-level trait dataset. Scientific Data 9:755.
Photosynthesis Direct fact

A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.

Kattge, J. et al. TRY plant trait database — Categorical Traits Dataset (2012).
Derived values are computed from open data by a published method — labelled, cited, and never shown as a direct observation. Full methodology →
Sources for this entry (20) Open & cited
[01] Scientific name & family — USDA PLANTS (DwCA, Zenodo 17903503)
[02] Growth habit & duration — USDA PLANTS (DwCA, Zenodo 17903503)
[03] Native status & distribution — USDA PLANTS (DwCA, Zenodo 17903503)
[04] Common name — USDA PLANTS (via GBIF)
[05] Invasive / introduced status — US-RIIS v2.0 (USGS)
[07] Description — Wikipedia (CC BY-SA)
[08] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts
[11] Functional traits — TRY Plant Trait Database (CC BY 4.0)
[12] Photosynthetic pathway — TRY Plant Trait Database (CC BY 4.0)
[13] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[16] Other common names — Wikidata (CC0)
[18] Flower-visitor value (derived) — Noori et al. 2026 (CC BY 4.0) · GloBI
[19] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[20] Caterpillar species — NHM HOSTS (CC0)
Spot an error or have a better photo? Every field links to its source, and the whole dataset is open.
Cite this page Open data, please attribute

PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).

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