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

Littorella americana — American shoreweed

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Facts

American shoreweed is a native plant of shallow lake water, sometimes emersing as water levels decline. It prefers sandy or gravelly substrates. A northern species, it is known only from Maine and Vermont in New England. The 1-inch (2 cm) long leaves of these tiny plants are stiffly spreading from a rosette and are rounded in cross-section. Separate "male" and "female" flowers are borne on the same plant, and are pollinated by wind. The plant can form colonies linked by stolons and rhizomes. Recreation and shoreline development threaten this plant, and several efforts are underway to restore degraded habitat for the species in Minnesota.

Habitat

Lacustrine (in lakes or ponds)

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
  • Maine
  • New Hampshire
  • Vermont
Flower petal color
white
Leaf type
the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
Leaf arrangement
whorled: there are three or more leaves per node along the stem
Leaf blade edges
the edge of the leaf blade is entire (has no teeth or lobes)
Flower symmetry
there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
Number of sepals, petals or tepals
  • there are four petals, sepals, or tepals in the flower
  • there are three petals, sepals, or tepals in the flower
Fusion of sepals and petals
NA
Stamen number
4
Fruit type (general)
the fruit is dry but does not split open when ripe
Fruit length
1–2 mm
Show all characteristics

  • Clonal plantlets

    Bulbils
    the plant does not appear to have bulbils
    Bulblets replace flowers
    there are no bulblets where the flowers are located

  • Flowers

    Anther opening
    the anthers have narrow slits or furrows that run lengthwise along the anthers
    Anther spurs
    the anthers do not have spurs on them
    Calyx symmetry
    there are two or more ways to evenly divide the calyx (the calyx is radially symmetrical)
    Carpels fused
    the carpels are fused to one another
    Cleistogamous flowers
    there are no cleistogamous flowers on the plan
    Corolla palate
    no
    Corona lobe length
    0 mm
    Epicalyx
    the flower does not have an epicalyx
    Epicalyx number of parts
    0
    Filament surface
    the filament is smooth, with no hairs or scales
    Flower description
    the flower has a superior ovary, and lacks a hypanthium
    Flower number
    1–3
    Flower petal color
    white
    Flower reproductive parts
    the flower has either only pollen- or only seed-producing parts
    Flower symmetry
    there are two or more ways to evenly divide the flower (the flower is radially symmetrical)
    Flowers sunken into stem
    no
    Form of style
    • the style is knob-like at the tip, and unbranched
    • the style is lobed at the tip, and unbranched
    Fused stamen clusters
    NA
    Fusion of sepals and petals
    NA
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower does not have a hypanthium
    Inflorescence one-sided
    the flowers are arrayed in a spiral around the inflorescence axis or branches, or occur singly, or in several ranks
    Inner tepals (Rumex)
    NA
    Nectar spur
    the flower has no nectar spurs
    Number of pistils
    • 1
    • 2
    Number of sepals, petals or tepals
    • there are four petals, sepals, or tepals in the flower
    • there are three petals, sepals, or tepals in the flower
    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 and sepal colors
    white
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal folds or pleats
    the petals of the flower do not have folds or plaits
    Petal hairs (Viola)
    NA
    Petal number
    3–4
    Petal tips (Cuscuta)
    NA
    Reproductive system
    each flower has only carpels or only stamens, but both types of flower are present on each plant (monoecious)
    Scales inside corolla
    no
    Sepal and petal color
    the sepals are different from the petals
    Sepal appendages
    the sepals do not have appendages on them
    Sepal appendages (Oenothera)
    NA
    Sepal number
    3–4
    Stamen attachment
    the stamens are attached at or near the bases of the petals or tepals
    Stamen number
    4
    Stamen position relative to petals
    the stamens are lined up with the sepals
    Umbel flower reproductive parts
    NA

  • Fruits or seeds

    Achene relative orientation
    NA
    Achene shape
    NA
    Achene surface (Polygonum)
    NA
    Achene type
    NA
    Berry color
    NA
    Capsule color (Viola)
    NA
    Capsule ribs
    NA
    Capsule splitting
    the capsule splits by two main valves, teeth or pores
    Fruit (pyxis) dehiscence
    NA
    Fruit features (Brassicaceae)
    NA
    Fruit length
    1–2 mm
    Fruit locules
    one
    Fruit type (general)
    the fruit is dry but does not split open when ripe
    Fruit type (specific)
    the fruit is an achene (dry, usually one-seeded, does not separate or split open at maturity)
    Legumes (Fabaceae)
    NA
    Mericarp length
    0 mm
    Mericarp segment shape (Desmodium)
    NA
    Other markings on berry
    NA
    Ovary stipe
    the ovary or fruit does not have a stipe
    Placenta arrangement
    the plant has axile placentation, in which the ovules are attached where the septa of a compound ovary are united, usually on the central axis, or to the septa themselves
    Rows of seeds in fruit (Brassicaceae)
    NA
    Schizocarpic fruit compression
    NA
    Schizocarpic fruit segments
    0
    Seed number
    1
    Septum in fruit (Brassicaceae)
    NA
    Wings on fruit
    the fruit does not have wings on it
    prickles on fruits
    the fruits do not have thorn-like defensive structures

  • Glands or sap

    Glands on leaf blade
    the leaf blades do not have glandular dots or scales
    Sap
    the sap is clear and watery
    Sap color
    the sap is clear

  • Growth form

    Growth form
    the plant is an herb (it has self-supporting stems)
    Horizontal rooting stem
    the plant does not have stolons
    Lifespan
    the plant lives more than two years
    Parasitism
    the plant is not parasitic
    Plant color
    the leaves or young stems of the plant are green
    Plants darken when dry
    no
    Spines on plant
    the plant has no spines

  • Leaves

    Bracteole number (Apiaceae)
    0
    Bracts in plantain (Plantago)
    NA
    Final leaf segment length (compound lvs only)
    0 mm
    Final leaf segment length to width ratio (compound lvs only)
    0
    Final leaf segment width (compound lvs only)
    0 mm
    Hairs on underside of leaf
    the underside of the leaf is not hairy, or it has very few hairs
    Leaf arrangement
    whorled: there are three or more leaves per node along the stem
    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 edges
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf blade length
    Up to 50 mm
    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 duration
    the leaves drop off in winter (or they whither but persist on the plant)
    Leaf form
    the leaves are green, with an expanded blade and a leaf-like texture
    Leaf spines
    there are no spines on the leaf edges
    Leaf stalk
    the leaves have no leaf stalks, but attach directly to the stem
    Leaf teeth and lobes
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaf variation
    NA
    Leaflet number
    0
    Leaves per node
    the leaves are growing only at the base of the plant (i.e., basal)
    Pinnately compound leaf type
    NA
    Specific leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Stipels
    NA
    Stipule features
    NA
    Stipules
    there are no stipules on the plant

  • Place

    Habitat
    • aquatic
    • wetlands
    New England state
    • Maine
    • New Hampshire
    • Vermont
    Specific habitat
    in lakes or ponds

  • Scent

    Plant odor
    the plant does not have much of a smell

  • Stem, shoot, branch

    Branched tendrils
    NA
    Flowering stem cross-section
    the flowering stem is circular, or with lots of small angles so that it is roughly circular
    Hair between stem nodes
    NA
    Hairs between stem nodes
    NA
    Leaves on stem
    the flowering stem has no leaves above the base
    Plant height
    Up to 5 cm
    Stem roughness between nodes
    the stem does not feel rough
    Tendril origin
    NA
    Tendrils
    the plant does not have tendrils

Wetland status

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

In New England

Distribution

Connecticut
absent
Maine
present
Massachusetts
absent
New Hampshire
present
Rhode Island
absent
Vermont
present

Conservation status

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

Vermont
rare (S-rank: S2)

From Flora Novae Angliae dichotomous key

1.  Littorella americana Fern. N

American shoreweed. Littorella uniflora (L.) Aschers. var. americana (Fern.) Gleason; Plantago americana (Fern.) K. Rahn • ME, NH, VT. Shallow water of lakes, sometimes emersed as water levels decline later in season.

Native to North America?

Yes

Sometimes confused with

Ranunculus flammula:
flowers with short, but conspicuous, yellow petals, and plants connected by arching, green stolons (va. L. Americana, with flowers lacking conspicuous yellow petals and plants connected by white stolons).

Synonyms

  • Littorella uniflora (L.) Aschers. var. americana (Fern.) Gleason
  • Plantago americana (Fern.) K. Rahn

Family

Plantaginaceae

Genus

Littorella