- You are here:
- Dichotomous Key
- Iridaceae
- Iris
- Iris pseudacorus
Iris pseudacorus — yellow iris
Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.
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)
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
Found this plant? Take a photo and post a sighting.
Characteristics
- Habitat
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- 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 shape
- the leaf blade is linear (very narrow with more or less parallel sides)
- Leaf blade length
- 400–1000 mm
- Flower petal color
- yellow
- Flower petal length
- 20–30 mm
- Petal fusion
- the perianth parts are fused to form a tube, cup, or bell shape
- 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)
- Ovary position
- the ovary is below the point of petal and/or sepal attachment
- 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)
- Fruit length
- 35–60 mm
-
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)
In New England
Distribution
- Connecticut
- present, invasive, prohibited
- Maine
- present
- Massachusetts
- present, invasive, prohibited
- New Hampshire
- present, invasive, prohibited
- Rhode Island
- present
- Vermont
- present, invasive
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- unranked (S-rank: SNR)
From Flora Novae Angliae dichotomous key
6. Iris pseudacorus L. E
yellow iris. CT, MA, ME, NH, RI, VT. Marshes, river and lake shores.