• You are here:
• Dichotomous Key
• Iridaceae
• Iris
• Iris pseudacorus

Iris pseudacorus — yellow iris

Facts

Yellow iris is native to Europe, northern Africa, and Asia, and has escaped cultivation in North America. It is widely distributed and considered invasive in many areas including New England.

Habitat

Marshes, shores of rivers or lakes, wetland margins (edges of wetlands)

Characteristics

• Clonal plantlets

  Axillary bulblets

  there are no bulblets being produced in axils

• Flowers

  Anther attachment

  the anther is attached by its base to the filament

  Bulblets replace flowers

  there are no bulblets where the flowers are located

  Carpels fused

  the carpels are fused (the number of carpels equals the number of locules)

  Flower bracts

  there are bracts associated with the flower

  Flower number

  4–12

  Flower orientation

  the flowers point upward or spread or curve outward

  Flower petal color

  yellow

  Flower petal length

  20–30 mm

  Flower shape

  the flower has a tube-shaped corolla

  Flower symmetry

  there are two or more ways to evenly divide the flower (the flower is radially symmetrical)

  Flowering stem width

  6–10 mm

  Form of style

  the style is branched above the base

  Fringed petal edges

  the petals are not fringed

  Inflorescence type

  the inflorescence is a monochasial cyme (an axis with a terminal flower, below it a branch with a terminal flower, this branch may itself have a branch and so on)

  Length of flower stalk

  25–70 mm

  Length of peduncle

  20–50 mm

  Marks on petals

  there are no noticeable marks on the petals

  Nectar spur

  the flower has no nectar spurs

  Number of carpels

  3

  Number of pistils

  1

  Number of sepals and/or petals

  there are six petals, sepals or tepals in the flower

  Number of styles

  1

  Ovary position

  the ovary is below the point of petal and/or sepal attachment

  Petal and sepal arrangement

  the flower includes two cycles of petal- or sepal-like structures

  Petal appearance

  the petals are thin and delicate, and pigmented (colored other than green or brown)

  Petal base

  the petal narrows abruptly at the base

  Petal fusion

  the perianth parts are fused to form a tube, cup, or bell shape

  Petal hairs on inner/upper surface

  • there are hairs on the inner/upper petal surface
  • there are no hairs on the inner/upper petal surface

  Sepal appearance

  the sepals resemble petals in color and texture

  Sepal length

  50–75 mm

  Sepal orientation

  the sepals are slightly curved outwards from the plant

  Sepals fused only to sepals

  the sepals are separate from one another

  Spathe

  • the plant does not have a spathe
  • the plant has a spathe surrounding the flower spike

  Spathe form

  NA

  Spathe length

  60–90 mm

  Stamen number

  3

  Stamen position relative to petals

  the stamens are lined up with the sepals

  Stamen types

  the stamens within a cycle are all similar

  Stamens fused

  the stamens are not fused to one another

  Stamens fused outwards

  the stamens are fused to the petals or tepals at or near their bases

  Style length

  30–40 mm

  Style petal-like

  the style is broad and flattened like a petal

  Tepals

  the petals and sepals are similar in size and color

• Fruits or seeds

  Berry color

  NA

  Capsule ridges

  there are three ribs or wings on the capsule

  Fruit beak length

  Up to 5 mm

  Fruit compartments

  there are three locules in the fruit

  Fruit cross-section

  • the fruit is another shape in cross-section
  • the fruit is at least somewhat flattened

  Fruit length

  35–60 mm

  Fruit stalk orientation

  the fruits curve or droop downwards

  Fruit type (general)

  the fruit is dry and splits open when ripe

  Fruit type (specific)

  the fruit is a capsule (splits along two or more seams, apical teeth or pores when dry, to release two or more seeds)

  Other markings on berry

  NA

• Glands or sap

  Sap

  the sap is clear and watery

• Growth form

  Lifespan

  the plant lives more than two years

  Root septa

  the roots do not have transverse septa

  Underground organs

  • the plant has a rhizome (a horizontal underground stem with roots growing from it)
  • there are only slender roots on the plant

• Leaves

  Hairs on underside of leaf blade

  the underside of the leaf is not hairy, or has very few hairs

  Leaf arrangement

  • alternate: there is one leaf per node along the stem
  • the leaves are growing only at the base of the plant (basal)

  Leaf blade basal lobes

  the leaf blades do not have basal lobes

  Leaf blade base

  the leaf has no stalk

  Leaf blade base shape

  the base of the leaf blade is cuneate (wedge-shaped, tapers to the base with relatively straight, converging edges), or narrow

  Leaf blade bloom

  the underside of the leaf blade has a noticeable waxy or powdery bloom

  Leaf blade cross-section

  the leaf blade is more or less flat in cross-section

  Leaf blade faces

  the surfaces of the leaf blade are composed of tissues from the abaxial side only

  Leaf blade form

  Fully-formed (i.e., expanded), +/- green leaf blades are found somewhere on the plant

  Leaf blade length

  400–1000 mm

  Leaf blade orientation

  the edge of the leaf blade faces the stem of the plant

  Leaf blade shape

  the leaf blade is linear (very narrow with more or less parallel sides)

  Leaf blade surface colors

  the upper side of the leaf blade is relatively uniform in color

  Leaf blade tip

  the tip of the leaf blade is acute (sharply pointed)

  Leaf blade veins

  the lateral veins are parallel or slightly arched in the direction of the tip

  Leaf blade width

  20–30 mm

  Leaf stalk length

  0 mm

  Leaf type

  the leaves are simple (lobed or unlobed but not separated into leaflets

  Leaflet number

  0

  Stipule twining

  NA

  Stipules

  there are no stipules on this plant

• Place

  Habitat

  wetlands

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont

  Specific habitat

  • edges of wetlands
  • marshes
  • shores of rivers or lakes

• Scent

  Plant odor

  the leaves have no particular smell

• Stem, shoot, branch

  Flowering stem growth form

  the flowering stem is held upright

  Flowering stem interior

  the flowering stem is solid

  Flowering stem leaves

  there is at least one fully-formed leaf on the flowering stem

  Stem hairs

  the stem is nearly or completely hairless

Wetland status

Occurs only in wetlands. (Wetland indicator code: OBL)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae