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

Drosera filiformis — thread-leaved sundew

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Facts

Thread-leaved sundew has a multiply-disjunct near-coastal distribution ranging from the Florida panhandle to Nova Scotia, including southern New England. In Massachusetts (and formerly in Connecticut and Rhode Island) it can be found on coastal plain pond shores and fens.

Habitat

Fens, shores of rivers or lakes

New England distribution

Adapted from BONAP data

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

North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Massachusetts
  • Rhode Island
Flower petal color
blue to purple
Leaf type
the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
Leaf arrangement
basal: the leaves are growing only at the base of the plant
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 five petals, sepals, or tepals in the flower
Fusion of sepals and petals
  • both the petals and sepals are separate and not fused
  • the petals or the sepals are fused into a cup or tube
Stamen number
5
Fruit type (general)
the fruit is dry and splits open when ripe
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 by its base to the filament
    Anther color
    the anthers show no hint of a pink, reddish or purplish tint
    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
    Anther tube length
    0 mm
    Calyx growth after flowering
    the calyx does not grow to cover or partially cover the fruit
    Calyx symmetry
    there are two or more ways to evenly divide the calyx (the calyx is radially symmetrical)
    Carpel hairs
    the carpels have no hairs
    Carpels fused
    the carpels are fused to one another
    Cilia on petals
    the petal margins do not have cilia
    Cleistogamous flowers
    there are no cleistogamous flowers on the plan
    Corolla morphology
    NA
    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 appearance
    the flowers appear at the same time as the leaves
    Flower description
    the flower has a superior ovary, and lacks a hypanthium
    Flower number
    4–16
    Flower orientation
    • the flower bends downwards or hangs downwards
    • the flower points upwards or is angled outwards
    Flower petal color
    blue to purple
    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 flower has two or more completely separate styles
    Fringed petal edges
    the petals are fringed
    Fused stamen clusters
    NA
    Fusion of sepals and petals
    • both the petals and sepals are separate and not fused
    • the petals or the sepals are fused into a cup or tube
    Hairs on flower stalk
    the flower stalk has hairs on it
    Hairs on inflorescence
    the axis of the inflorescence has no hairs on it
    Horns in hoods (Asclepias)
    NA
    Hypanthium
    the flower does not have a hypanthium
    Hypanthium length
    0 mm
    Inflorescence length
    40–150 mm
    Inflorescence one-sided
    the flowers are all or nearly all arrayed on one side of the inflorescence axis or branches of the inflorescence
    Inner tepals (Rumex)
    NA
    Interior flower disk
    the flower does not have an interior disc
    Length of peduncle
    60–220 mm
    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 carpels
    3
    Number of pistils
    1
    Number of sepals, petals or tepals
    there are five petals, sepals, or tepals in the flower
    Number of styles
    3
    Ovary position
    the ovary is above the point of petal and/or sepal attachment
    Perianth shape
    the perianth is another shape
    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 base
    the petal narrows gradually or does not narrow at the base
    Petal folds or pleats
    the petals of the flower do not have folds or plaits
    Petal hairs (Viola)
    NA
    Petal length
    8–15 mm
    Petal length relative to sepals
    the petals are longer than the sepals
    Petal nectaries
    the petals do not have nectaries
    Petal number
    5
    Petal shape
    the petal outline is ovate (widest below the middle and broadly tapering at both ends)
    Petal tip shape
    the petal tip is lobed or fringed
    Petal tips (Cuscuta)
    NA
    Petal width
    5–8 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 appearance
    the sepals are green or brown, and leaf-like in texture
    Sepal appendages
    the sepals do not have appendages on them
    Sepal appendages (Oenothera)
    NA
    Sepal auricles
    the sepals have no auricles
    Sepal cilia
    the sepals do not have cilia
    Sepal color
    green to brown
    Sepal features
    one or more sepals have glands that are raised from the surface by a stalk
    Sepal length
    4–7 mm
    Sepal number
    5
    Sepal orientation
    the sepals are slightly curved outwards from the corolla
    Sepal relative length
    • the sepal lobes are approximately the same length as the fused portion
    • the sepal lobes are longer than the fused portion
    Sepal shape
    • the sepal outline is oblong (rectangular, but with rounded ends)
    • the sepal outline is ovate (widest below the middle and broadly tapering at both ends)
    Sepal texture
    the sepals are fleshy or spongy
    Sepal tip shape
    • the sepal tip is acute (is sharply pointed)
    • the sepal tip is obtuse (is bluntly pointed)
    Sepal uniformity
    all the sepals are about the same size
    Sepals fused only to sepals
    • the sepals are fused to each other (not other flower parts), at least near their bases
    • the sepals are separate from one another
    Spur length
    0 mm
    Spur number
    NA
    Stamen appendages
    stamen appendages are absent
    Stamen lengths differ
    the stamens are all approximately the same length
    Stamen morphology
    the stamens within each cycle are the same
    Stamen number
    5
    Stamen position relative to petals
    the stamens are lined up with the sepals
    Stamens fused
    the stamens are not attached to one another
    Staminodes
    there are no staminodes on the flower
    Stigma position
    the stigmas are positioned at the tip of the style
    Style petal-like
    the styles are not petal-like
    Style relative length
    the stigma does not protrude beyond the mouth of the corolla
    Surface of ovary
    the ovary surface has no points, bumps or wrinkles
    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 ribs
    the capsule has three prominent ribs or wings
    Capsule splitting
    the capsule splits by three main valves, teeth or pores
    Carpel beak length
    0 mm
    Fruit (pyxis) dehiscence
    NA
    Fruit beak length
    0 mm
    Fruit cross-section
    the fruit is round in cross-section
    Fruit features (Brassicaceae)
    NA
    Fruit length relative to sepals
    the fruit is about the same length as its associated sepals
    Fruit locules
    one
    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
    Ovary stipe length
    0 mm
    Placenta arrangement
    the plant has parietal placentation, where ovules develop on the wall or slight outgrowths of the wall forming broken partitions within a compound ovary
    Rows of seeds in fruit (Brassicaceae)
    NA
    Schizocarpic fruit compression
    NA
    Schizocarpic fruit segments
    0
    Seed length
    0.5–0.8 mm
    Seed number
    At least 3
    Seed relative length
    the seed is longer than it is wide
    Seed surface
    • the seed has a surface characteristic other than those listed
    • the seed has pits or depressions on it
    Seeds comose
    no hairs
    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
    • insectivorous
    • 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
    Underground organs
    the plant has one or more swollen storage organs underground, such as bulbs, tubers or corms

  • Leaves

    Bracteole edges
    NA
    Bracteole length
    0 mm
    Bracteole number (Apiaceae)
    0
    Bracteole shape
    NA
    Bracteoles
    there are no bracteoles on the plant
    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
    NA
    Floral bracts
    the flower does not have bracts
    Flower bract length
    0 mm
    Hairs on leaf stalk
    the petiole has hairs on it
    Hairs on upper side of leaf
    the upper side of the leaf is fuzzy or hairy
    Hooked hairs on underside of leaf
    no
    Inflated hairs on leaf
    the leaf blade does not have inflated hairs on it
    Leaf arrangement
    basal: the leaves are growing only at the base of the plant
    Leaf blade base
    the leaf has a distinct leaf stalk (petiole)
    Leaf blade base symmetry
    the leaf blade base is symmetrical
    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 flatness
    the leaf is flat (planar) at the edges
    Leaf blade hairs
    the leaf blade has hairs with glands at their tips
    Leaf blade length
    80–250 mm
    Leaf blade primary vein pattern
    NA
    Leaf blade shape
    the leaf blade is filiform (extremely narrow, thread-like)
    Leaf blade surface colors
    the upper side of the leaf blade is relatively uniform in color
    Leaf blade texture
    the leaf blade has a fleshy or spongy texture
    Leaf blade vein pattern
    NA
    Leaf blade veins
    NA
    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 hair orientation
    the hairs are standing up straight or curved in different directions
    Leaf spines
    there are no spines on the leaf edges
    Leaf stalk
    the leaves have leaf stalks
    Leaf stalk attachment to leaf
    the petiole attaches at the basal margin of the leaf blade
    Leaf stalk base
    the petiole base is narrow where it attaches to the stem
    Leaf teeth and lobes
    the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf tufts in axils
    there are no clusters of smaller leaves growing out of axils
    Leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaf types
    NA
    Leaf variation
    NA
    Leaflet number
    0
    Leaflet petiolules
    NA
    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
    Stipule fused to leaf stalk
    the stipules are fused to the petioles for some or most of their length
    Stipule shape
    the stipules are another shape than the choices given
    Stipules
    the plant has stipules
    Teeth per side of leaf blade
    0

  • Place

    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Massachusetts
    • Rhode Island
    Specific habitat
    • fens
    • shores of rivers or lakes

  • Scent

    Plant odor
    the plant does not have much of a smell

  • Stem, shoot, branch

    Branched tendrils
    NA
    Hooked hairs on stem between nodes
    no
    Leaves on stem
    the flowering stem has no leaves above the base
    Stem nodes swollen
    the stem is not swollen at the nodes
    Stem orientation
    the stems are upright or angled outwards
    Stem roughness between nodes
    the stem does not feel rough
    Stem spacing
    the plant is solitary, or a few plants are growing together
    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
Maine
absent
Massachusetts
present
New Hampshire
absent
Rhode Island
present
Vermont
absent

Conservation status

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

Connecticut
historical (S-rank: SH), special concern, extirpated (code: SC*)
Rhode Island
historical (S-rank: SH), state historical (code: SH)

var. filiformis

Massachusetts
fairly widespread (S-rank: S4)

Subspecies and varieties

Our variety is Drosera filiformis Raf. var. filiformis.

From Flora Novae Angliae dichotomous key

2.  Drosera filiformis Raf. var. filiformis N

thread-leaved sundew. CT, MA, RI; coastal plain. Coastal plain pond shores, fens.

Native to North America?

Yes

Sometimes confused with

Drosera linearis:
leaf blades broad-linear, clearly differentiated from the petiole, and petals white to pink, 5-6 mm long (vs. D. filiformis, with leaf blades filiform, scarcely differentiated from the petiole and petals purple, 8–15 mm long).

Family

Droseraceae

Genus

Drosera