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

Lythrum salicaria — purple loosestrife

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Facts

A very aggressive invader of sunny wetlands, purple loosestrife displaces native species and reduces plant and animal diversity. Don't let the attractive persistent flowers fool you--this one is not an asset to New England.

Habitat

Anthropogenic (man-made or disturbed habitats), marshes, meadows and fields, shores of rivers or lakes, swamps, wetland margins (edges of wetlands)

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Flower petal color
  • blue to purple
  • pink to red
Leaf type
the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
Leaf arrangement
  • alternate: there is one leaf per node along the stem
  • opposite: there are two leaves per node along the stem
  • 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 six petals, sepals, or tepals in the flower
Fusion of sepals and petals
both the petals and sepals are separate and not fused
Stamen number
12
Fruit type (general)
the fruit is dry and splits open when ripe
Fruit length
3–4 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 attachment
    the anther is attached near its midpoint to the filament
    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 has an epicalyx
    Epicalyx number of parts
    0–6
    Filament surface
    the filament is smooth, with no hairs or scales
    Flower description
    the flower has a superior ovary and a hypanthium
    Flower petal color
    • blue to purple
    • pink to red
    Flower reproductive parts
    the flower has both pollen- and 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
    Fused stamen clusters
    NA
    Fusion of sepals and petals
    both the petals and sepals are separate and not fused
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower has a hypanthium
    Hypanthium length
    4.5 mm
    Inflorescence length
    150–350 mm
    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
    Interior flower disk
    the flower does not have an interior disc
    Marks on petals
    there are no noticeable marks on the petals
    Nectar spur
    the flower has no nectar spurs
    Number of branches in umbel
    0
    Number of sepals, petals or tepals
    there are six 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 and sepal colors
    • blue to purple
    • pink to red
    Petal appearance
    the petals are thin and delicate, and pigmented (colored other than green or brown)
    Petal folding in bud
    the petals in bud are crumpled erratically
    Petal folds or pleats
    the petals of the flower do not have folds or plaits
    Petal hairs (Viola)
    NA
    Petal length
    7–10 mm
    Petal number
    6
    Petal shape
    • the petal outline is lanceolate (lance-shaped; narrow, gradually tapering from the base to the tip)
    • the petal outline is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
    Petal tips (Cuscuta)
    NA
    Petal width
    1.5–3 mm
    Raceme attachment (Veronica)
    NA
    Reproductive system
    all the flowers have both carpels and stamens (synoecious)
    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 color
    • green to brown
    • pink to red
    Sepal length
    0.5–1 mm
    Sepal number
    6
    Sepal relative length
    the sepal lobes are shorter than the fused portion
    Sepal shape
    the sepal outline is roughly triangular
    Sepal texture
    • the sepals are either very thin but flexible, like a membrane, or they are leaf-like in texture
    • the sepals are firm or rigid
    Sepals fused only to sepals
    the sepals are fused to each other (not other flower parts), at least near their bases
    Spur length
    0 mm
    Spur number
    NA
    Stamen morphology
    the stamens within a cycle differ in length or width
    Stamen number
    12
    Stamen relative length
    anything
    Staminodes
    there are no staminodes on the flower
    Style length
    Up to 7 mm
    Style petal-like
    the styles are not petal-like
    Style relative length
    the stigma protrudes beyond the mouth of the corolla
    Umbel flower reproductive parts
    NA
    Upper lip of bilabiate corolla
    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 splitting
    the capsule splits by two main valves, teeth or pores
    Fruit (pyxis) dehiscence
    NA
    Fruit features (Brassicaceae)
    NA
    Fruit length
    3–4 mm
    Fruit locules
    two
    Fruit shape
    the fruit is ovoid (egg-shaped)
    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)
    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
    • the plant has free-central placentation, where the ovules develop on a central column in a compound ovary lacking septa or with septa at the base only
    Rows of seeds in fruit (Brassicaceae)
    NA
    Schizocarpic fruit compression
    NA
    Schizocarpic fruit segments
    0
    Seed length
    1 mm
    Seed relative length
    the seed is longer than it is wide
    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)
    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
    Bracteoles
    the plant has bracteoles between the primary bracts and the flowers
    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
    Floral bract texture
    the floral bracts are green, with a leaf-like texture
    Floral bracts
    the flower has one or more bracts associated with it
    Hairs on leaf stalk
    NA
    Hooked hairs on underside of leaf
    no
    Inflated hairs on leaf
    the leaf blade does not have inflated hairs on it
    Leaf arrangement
    • alternate: there is one leaf per node along the stem
    • opposite: there are two leaves per node along the stem
    • whorled: there are three or more leaves per node along the stem
    Leaf blade base
    • the leaf has no stalk
    • the leaf has no stalk and at the base it clasps the stem
    Leaf blade base shape
    • the base of the leaf blade is cordate (heart-shaped, has rounded lobes at the base)
    • the base of the leaf blade is truncate (ends abruptly in a more or less straight line as though cut off)
    Leaf blade bloom
    the underside of the leaf has no noticeable bloom
    Leaf blade edges
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf blade length
    25–100 mm
    Leaf blade primary vein pattern
    the secondary veins branch off at intervals from the primary vein
    Leaf blade shape
    • the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    • 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 texture
    the leaf blade is herbaceous (has a leafy texture)
    Leaf blade veins
    the leaf blade has one main vein running from the base towards the tip (it may or may not have secondary veins)
    Leaf blade width
    5–15 mm
    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 sheath length
    0 mm
    Leaf shiny
    the upper side of the leaf is dull or slightly shiny
    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 stalk attachment to leaf
    NA
    Leaf stalk base
    NA
    Leaf stalk length
    0 mm
    Leaf teeth and lobes
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf tip
    the tip of the leaf blade is acute (sharply pointed)
    Leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaf variation
    the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
    Leaflet number
    0
    Leaflet petiolules
    NA
    Leaves per node
    • there are three leaves per node along the stem
    • there are two leaves per node along the stem
    • there is one leaf per node along the stem
    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 edges
    NA
    Stipule features
    NA
    Stipule fused to leaf stalk
    NA
    Stipule length
    0 mm
    Stipule shape
    NA
    Stipules
    there are no stipules on the plant
    Teeth per side of leaf blade
    0

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of wetlands
    • man-made or disturbed habitats
    • marshes
    • meadows or fields
    • shores of rivers or lakes
    • swamps

  • 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 roughly square
    Hair between stem nodes
    the stem has hairs between the nodes
    Hairs between stem nodes
    • at least some of the hairs on the stem are tangled, matted or woolly
    • the hairs on the stem are plain, without glands or branches, and not tangled
    Hooked hairs on stem between nodes
    no
    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Plant height
    50–150 cm
    Stem bloom
    there is no powdery or waxy film on the stem
    Stem hair distribution
    the hairs on the stem are distributed more of less uniformly
    Stem orientation
    the stems are upright or angled outwards
    Stem roughness between nodes
    the stem does not feel rough
    Tendril origin
    NA
    Tendrils
    the plant does not have tendrils
    Wings on stem
    the stem does not have wings on it

Wetland status

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

In New England

Distribution

Connecticut
present, invasive, prohibited
Maine
present, invasive, prohibited
Massachusetts
present, invasive, prohibited
New Hampshire
present, invasive, prohibited
Rhode Island
present, invasive
Vermont
present, invasive, prohibited

Conservation status

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

Connecticut
not applicable (S-rank: SNA)
Maine
not applicable (S-rank: SNA)
Massachusetts
not applicable (S-rank: SNA)

From Flora Novae Angliae dichotomous key

5.  Lythrum salicaria L. E

purple loosestrife. Lythrum salicaria L. var. gracilior Turcz.; L. salicaria L. var. tomentosum 
 (P. Mill.) DC. • CT, MA, ME, NH, RI, VT. Swamps, marshes, shorelines, wet ditches, low fields.

Native to North America?

No

Sometimes confused with

Chamerion angustifolium:
flowers with 4 petals, leaves alternate, and seeds with a tuft of white hairs (vs. L. salicaria, with flowers with 6 petals, leaves opposite or whorled, and seeds without hairs).
Lythrum virgatum:
intersepalar appendages ca. 1 mm long, about as long as or shorter than the sepals, plants glabrous throughout, and leaf blades tapering to the base (vs. L. salicaria, with intersepalar appendages 2.5–3 mm long, usually longer than the sepals, plants generally pubescent on the stem and/or leaf blades, leaf blades usually truncate to subclasping at the base).

Synonyms

  • Lythrum salicaria var. gracilior Turcz.
  • Lythrum salicaria var. tomentosum (P. Mill.) DC.

Family

Lythraceae

Genus

Lythrum