Your help is appreciated. We depend on donations to help keep this site free and up to date for you. Can you please help us?

Donate

Native Plant Trust: Go Botany Discover thousands of New England plants

Acorus calamus — single-veined sweetflag

Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.

Facts

Because single-veined sweetflag has three sets of chromosomes, it is sterile and cannot produce fruit. European settlers brought it to North America and grew it for medicinal purposes. It propagates readily through spread of the rhizomes, and has spread throughout the eastern and midwestern United States, with scattered instances elsewhere. The rhizome has medicinal properties and has been used to treat a variety of conditions from nausea, heartburn, and colds to fatigue and anxiety.

Habitat

Lacustrine (in lakes or ponds), marshes, riverine (in rivers or streams), shores of rivers or lakes, wetland margins (edges of wetlands)

New England distribution

Adapted from BONAP data

Found this plant? Take a photo and post a sighting.

North America distribution

Adapted from BONAP data

enlarge

Characteristics

Habitat
  • aquatic
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf arrangement
basal: the leaves are growing only at the base of the plant
Leaf blade shape
the leaf blade is linear (very narrow with more or less parallel sides)
Leaf blade length
299–1750 mm
Flower petal color
  • green to brown
  • yellow
Flower petal length
3–4 mm
Petal fusion
the perianth parts are separate
Inflorescence type
the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
Ovary position
the ovary is above the point of petal and/or sepal attachment
Fruit type (specific)
  • NA
  • the fruit is a berry (fleshy, with the wall enclosing one or more sections, with two or more seeds)
Fruit length
0 mm
Show all 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
    Anther color
    the anthers show no hint of a pink, reddish or purplish tint
    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)
    Filament surface
    the filament surface has no hairs or scales on it
    Flower bract length
    15–90 mm
    Flower bracts
    there are bracts associated with the flower
    Flower orientation
    the flowers point upward or spread or curve outward
    Flower petal color
    • green to brown
    • yellow
    Flower petal length
    3–4 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)
    Form of style
    the style is knob-like at the tip, and unbranched
    Fringed petal edges
    the petals are not fringed
    Hairs on flower stalk
    NA
    Inflorescence hair glands
    the axis of the inflorescence has no hairs on it
    Inflorescence length
    38–89 mm
    Inflorescence type
    the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
    Inflorescence width
    5.3–10.8 mm
    Length of flower stalk
    0 mm
    Length of peduncle
    150–500 mm
    Marks on petals
    there are no noticeable marks on the petals
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    2–3
    Number of pistils
    1
    Number of sepals and/or petals
    there are six petals, sepals or tepals in the flower
    Number of styles
    0–1
    Ovary position
    the ovary is above the point of petal and/or sepal attachment
    Petal and sepal arrangement
    the flower includes only one cycle of petals or sepals
    Petal appearance
    the petals are green and/or leafy in texture
    Petal base
    the petal narrows gradually or does not narrow at the base
    Petal fusion
    the perianth parts are separate
    Petal hairs on inner/upper surface
    there are no hairs on the inner/upper petal surface
    Petal nectaries
    the petals do not have nectaries
    Sepal appearance
    the sepals resemble leaves in color and texture
    Sepal length
    3–4 mm
    Sepal orientation
    the sepals are pressed against the plant, or jutting stiffly upward
    Sepals fused only to sepals
    the sepals are separate from one another
    Spathe
    the plant does not have a spathe
    Spathe form
    NA
    Spathe length
    0 mm
    Stamen length
    1.7–2.9 mm
    Stamen number
    6
    Stamen position relative to petals
    NA
    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 not fused to the petals or tepals
    Style length
    At least 0 mm
    Style petal-like
    the style is not broad and flattened like a petal
    Tepals
    the petals and sepals are similar in size and color

  • Fruits or seeds

    Berry color
    • NA
    • brown
    • green
    Capsule ridges
    NA
    Fruit beak length
    0 mm
    Fruit cross-section
    the fruit is round in cross-section
    Fruit length
    0 mm
    Fruit stalk orientation
    NA
    Fruit type (general)
    • NA
    • the fruit is fleshy
    Fruit type (specific)
    • NA
    • the fruit is a berry (fleshy, with the wall enclosing one or more sections, with two or more seeds)
    Fruit width
    0 mm
    Other markings on berry
    • NA
    • the ripe fruits are mostly one color without spots or streaks
    • the ripe fruits have spots or streaks on them

  • 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
    Hairs on upper side of leaf blade
    NA
    Leaf arrangement
    basal: the leaves are growing only at the base of the plant
    Leaf blade basal lobes
    the leaf blades do not have basal lobes
    Leaf blade base
    the leaf has no stalk
    Leaf blade base shape
    NA
    Leaf blade bloom
    the underside of the leaf blade has no 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
    299–1750 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
    • NA
    • the upper side of the leaf blade is relatively uniform in color
    Leaf blade tip
    the tip of the leaf blade is acuminate (tapers to a long, thin point)
    Leaf blade veins
    the lateral veins are parallel or slightly arched in the direction of the tip
    Leaf blade width
    5–20 mm
    Leaf stalk length
    0 mm
    Leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets
    Leaflet number
    0
    Stipule twining
    NA
    Stipules
    there are no stipules on this plant

  • Place

    Habitat
    • aquatic
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of wetlands
    • in lakes or ponds
    • in rivers or streams
    • marshes
    • shores of rivers or lakes

  • Scent

    Plant odor
    the leaves smell of lemon, citrus or other fruit

  • Stem, shoot, branch

    Flowering stem growth form
    • the flowering stem is held upright
    • the flowering stem trails along the ground or on other vegetation, or floats in the water
    Flowering stem leaves
    there are no true leaves 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
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Massachusetts
not applicable (S-rank: SNA)

From Flora Novae Angliae dichotomous key

2.  Acorus calamus L. E

single-veined sweetflag. CT, MA, ME, NH, RI, VT. Marshes, lake borders, stream shores, and 
other open, wet areas.

Native to North America?

No

Sometimes confused with

Acorus americanus:
vegetative leaf blades mostly narrower than 10 mm, with 2-6 primary veins that are significantly broader than the fine, secondary veins (vs. A. calamus, with vegetative leaf blades mostly wider than 10 mm, with one primary vein that is significantly broader than the fine, secondary veins).

Family

Acoraceae

Genus

Acorus