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Sagittaria rigida — sessile-fruited arrowhead

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Facts

Sessile-fruited arrowhead is found in lakes, fresh and brackish tidal river shores, backwaters and pools. It reaches the northern edge of its range in New England and southern Canada. It differs from other arrowhead species of estuarine tidal marshes by its lobe-less leaves, its stalk-less fruits and its white flowers with pistils (male organs). It flowers from July to September.

Habitat

Brackish or salt marshes and flats, floodplain (river or stream floodplains), fresh tidal marshes or flats, lacustrine (in lakes or ponds), shores of rivers or lakes, swamps

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • aquatic
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont
Leaf arrangement
basal: the leaves are growing only at the base of the plant
Leaf blade shape
  • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes), or sagittate (arrow-shaped with backward-facing pointed lobes)
  • the leaf blade is elliptic (widest near the middle and tapering at both ends)
  • the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
  • the leaf blade is linear (very narrow with more or less parallel sides)
  • the leaf blade is oblong (rectangular but with rounded ends)
  • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
Leaf blade length
50–700 mm
Flower petal color
white
Flower petal length
8–14 mm
Petal fusion
the perianth parts are separate
Inflorescence type
the inflorescence is a raceme (a long unbranched stem with stalked flowers growing along it)
Ovary position
the ovary is above the point of petal and/or sepal attachment
Fruit type (specific)
the fruit is an achene (dry, usually 1-seeded, does not separate or split open at maturity)
Fruit length
2.5–4 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 carpel is solitary or (if 2 or more) the carpels are not fused to one another
    Filament surface
    the filament surface has rough hairs or scales on it
    Flower bract length
    4–6 mm
    Flower bracts
    there are bracts associated with the flower
    Flower orientation
    the flowers point upward or spread or curve outward
    Flower petal color
    white
    Flower petal length
    8–14 mm
    Flower shape
    the flower is flattened or platter-shaped
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Form of style
    the flower has two or more completely separate styles
    Fringed petal edges
    the petals are not fringed
    Hairs on flower stalk
    the flower stalk has no hairs on it
    Inflorescence hair glands
    the axis of the inflorescence has no hairs on it
    Inflorescence length
    80–100 mm
    Inflorescence type
    the inflorescence is a raceme (a long unbranched stem with stalked flowers growing along it)
    Inflorescence width
    20–60 mm
    Length of flower stalk
    0–30 mm
    Length of peduncle
    100–1150 mm
    Marks on petals
    • the petals have spots or streaks on them
    • there are no noticeable marks on the petals
    Nectar spur
    the flower has no nectar spurs
    Number of carpels
    At least 3
    Number of pistils
    6 or more
    Number of sepals and/or petals
    there are three petals, sepals or tepals in the flower
    Number of styles
    1
    Ovary position
    the ovary is above 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 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
    4–7 mm
    Sepal orientation
    the sepals are curved outwards and downwards
    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 number
    13 or more
    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 petal-like
    the style is not broad and flattened like a petal
    Tepals
    the petals and sepals are different in size and color

  • Fruits or seeds

    Berry color
    NA
    Capsule ridges
    NA
    Fruit beak length
    0.8–1.4 mm
    Fruit compartments
    there is only one locule in the fruit
    Fruit cross-section
    the fruit is at least somewhat flattened
    Fruit length
    2.5–4 mm
    Fruit stalk orientation
    the fruits point upward or spread or curve outward
    Fruit type (general)
    the fruit is dry but does not split open when ripe
    Fruit type (specific)
    the fruit is an achene (dry, usually 1-seeded, does not separate or split open at maturity)
    Fruit width
    1.3–1.6 mm
    Other markings on berry
    NA

  • Glands or sap

    Sap
    the sap is milky and opaque, and may be white or colored

  • Growth form

    Lifespan
    the plant lives more than two years
    Root septa
    the roots have transverse septa
    Underground organs
    the plant has one or more swollen storage organs underground, such as bulbs, tubers or corms

  • 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
    the upper side of the leaf is not hairy, or has very few hairs
    Leaf arrangement
    basal: the leaves are growing only at the base of the plant
    Leaf blade basal lobes
    • the leaf blades are lobed at their bases
    • the leaf blades do not have basal lobes
    Leaf blade base
    • the leaf has a distinct leaf stalk (petiole)
    • the leaf has no stalk
    Leaf blade base shape
    • The base of the leaf blade is cordate (heart-shaped, with rounded lobes) or sagittate (arrow-shaped, with pointed, backward-facing lobes)
    • 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 no noticeable waxy or powdery bloom
    Leaf blade cross-section
    the leaf blade is more or less flat in cross-section
    Leaf blade faces
    both surfaces of the leaf blade are exposed
    Leaf blade form
    Fully-formed (i.e., expanded), +/- green leaf blades are found somewhere on the plant
    Leaf blade length
    50–700 mm
    Leaf blade orientation
    the upper surface of the leaf blade faces the stem of the plant
    Leaf blade shape
    • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes), or sagittate (arrow-shaped with backward-facing pointed lobes)
    • the leaf blade is elliptic (widest near the middle and tapering at both ends)
    • the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    • the leaf blade is linear (very narrow with more or less parallel sides)
    • the leaf blade is oblong (rectangular but with rounded ends)
    • the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
    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)
    • the tip of the leaf blade is rounded, with no point
    Leaf blade veins
    the lateral veins are parallel or slightly arched in the direction of the tip
    Leaf blade width
    6–120 mm
    Leaf stalk length
    0–500 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
    • Vermont
    Specific habitat
    • brackish or salt marshes and flats
    • fresh tidal marshes or flats
    • in lakes or ponds
    • river or stream floodplains
    • shores of rivers or lakes
    • swamps

  • Scent

    Plant odor
    the leaves have no particular smell

  • Stem, shoot, branch

    Flowering stem growth form
    the flowering stem is held upright
    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.

Connecticut
unrankable (S-rank: SU)
Maine
rare (S-rank: S2), special concern (code: SC)
Massachusetts
rare (uncertain) (S-rank: S2?)
New Hampshire
historical (S-rank: SH), endangered (code: E)
Vermont
uncommon (S-rank: S3)

From Flora Novae Angliae dichotomous key

7.  Sagittaria rigida Pursh N

sessile-fruited arrowhead. CT, MA, ME, NH, VT; also reported for RI by George (1992), but specimens are unknown. Lakes, river shores, backwaters, and pools, including fresh to brackish-tidal rivers.

Native to North America?

Yes and no (some introduced)

Sometimes confused with

Sagittaria graminea:
leaf blades, when formed, mostly elliptic to oval and lowest whorl of flowers borne on evident stalks (vs. S. rigida, with leaf blades, when formed, narrow-lanceolate to broad-lanceolate and lowest whorl of flowers unstalked or borne on very short stalks).

Family

Alismataceae

Genus

Sagittaria