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

Knautia arvensis — bluebuttons, field scabiosa

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New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Facts

The seeds of bluebuttons have a fleshy appendage, called an eliosome, which is eaten by ants. Ants carry the seeds back to their nest, thus aiding in the plant's dispersal. Although this plant is not native to the United States, ants have been observed to use its eliosomes.

Habitat

Anthropogenic (man-made or disturbed habitats), meadows and fields

Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont
Flower petal color
blue to purple
Leaf type
  • the leaves are compound (made up of two or more discrete leaflets
  • the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
Leaf arrangement
opposite: there are two leaves per node along the stem
Leaf blade edges
  • the edge of the leaf blade has lobes, or it has both teeth and lobes
  • the edge of the leaf blade has teeth
  • 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)
  • there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
Number of sepals, petals or tepals
there are four petals, sepals, or tepals in the flower
Fusion of sepals and petals
the petals or the sepals are fused into a cup or tube
Stamen number
4
Fruit type (general)
the fruit is dry but does not split open when ripe
Fruit length
5–6 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 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
    Flower description
    the flower has an inferior ovary, with or without a hypanthium
    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)
    • there is only one way to evenly divide the flower (the flower is bilaterally symmetrical)
    Flowers sunken into stem
    no
    Fused stamen clusters
    NA
    Fusion of sepals and petals
    the petals or the sepals are fused into a cup or tube
    Hairs on inflorescence
    the axis of the inflorescence has hairs entirely without glands
    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
    Inflorescence width
    15–40 mm
    Inner tepals (Rumex)
    NA
    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 branches in umbel
    0
    Number of carpels
    2
    Number of sepals, petals or tepals
    there are four petals, sepals, or tepals in the flower
    Number of styles
    1
    Ovary position
    the ovary is below the point of petal and/or sepal attachment
    Perianth shape
    the perianth is cylindric (tube-shaped)
    Petal and sepal arrangement
    the flower includes two cycles of petal- or sepal-like structures
    Petal and sepal colors
    blue to purple
    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
    4
    Petal tips (Cuscuta)
    NA
    Raceme attachment (Veronica)
    NA
    Reproductive system
    the plant has flowers with both carpels and stamens, as well as flowers with only carpels or only stamens (polygamous)
    Scales inside corolla
    no
    Sepal and petal color
    • NA
    • 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 color
    green to brown
    Sepal length
    3–4 mm
    Sepal number
    6–24
    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
    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
    Stamen relative length
    anything
    Stamens fused
    the stamens are not attached to one another
    Staminodes
    there are no staminodes on the flower
    Style petal-like
    the styles are not petal-like
    Umbel flower reproductive parts
    NA

  • Fruits or seeds

    Achene relative orientation
    the achenes are perpendicular to the plane of the perianth (vertical)
    Achene surface (Polygonum)
    NA
    Achene type
    the fruit is an achene (dry, indehiscent, and usually one-seeded)
    Berry color
    NA
    Capsule color (Viola)
    NA
    Capsule ribs
    NA
    Capsule splitting
    NA
    Carpel beak length
    0 mm
    Fruit (pyxis) dehiscence
    NA
    Fruit features (Brassicaceae)
    NA
    Fruit length
    5–6 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)
    Hairs on fruit
    the fruits have hairs on them
    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 apical placentation, where one or a few ovules develop at the top of a simple or compound ovary
    Rows of seeds in fruit (Brassicaceae)
    NA
    Schizocarpic fruit compression
    NA
    Schizocarpic fruit segments
    0
    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
    • the plant has stolons
    Lifespan
    • the plant lives for two years
    • 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
    Spines on plant
    the plant has no spines
    Underground organs
    there is a thickened taproot on the plant

  • 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
    Floral bracts
    the flower has one or more bracts associated with it
    Flower bract length
    8–12 mm
    Hairs on underside of leaf
    the underside of the leaf is fuzzy or hairy
    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
    opposite: there are two leaves per node along the stem
    Leaf blade bloom
    the underside of the leaf has no noticeable bloom
    Leaf blade edges
    • the edge of the leaf blade has lobes, or it has both teeth and lobes
    • the edge of the leaf blade has teeth
    • the edge of the leaf blade is entire (has no teeth or lobes)
    Leaf blade hairs
    the leaf blade has simple hairs with no glands, and not tangled or wooly
    Leaf blade length
    Up to 25 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 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 scarious (thin and dry like paper) or membranaceous (thin and flexible and almost translucent like a membrane)
    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 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 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 leaf stalks
    • the leaves have no leaf stalks, but attach directly to the stem
    Leaf stalk attachment to leaf
    • NA
    • the petiole attaches at the basal margin of the leaf blade
    Leaf teeth and lobes
    • the edge of the leaf blade is entire (has no teeth or lobes)
    • the leaf blade margin has outward-pointing teeth
    Leaf tip
    the tip of the leaf blade is acute (sharply pointed)
    Leaf type
    • the leaves are compound (made up of two or more discrete leaflets
    • the leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaf types
    NA
    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 two leaves 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

  • Place

    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Vermont
    Specific habitat
    • man-made or disturbed habitats
    • meadows or fields

  • Stem, shoot, branch

    Branched tendrils
    NA
    Direction of stem hairs
    the hairs point mostly upwards to outwards
    Hair between stem nodes
    the stem has hairs between the nodes
    Hairs between stem nodes
    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
    30–100 cm
    Stem bloom
    there is no powdery or waxy film on the stem
    Stem hair distribution
    the hairs on the stem are mainly found on the edges or angles of the stem
    Stem orientation
    the stems are upright or angled outwards
    Stem roughness between nodes
    the stem does not feel rough
    Stem spacing
    the plant is growing in tufts, or compact clusters with closely spaced stems, or it is densely matted together in clumps, cushionlike
    Stem succulence
    the stems are not succulent
    Tendril origin
    NA
    Tendrils
    the plant does not have tendrils
    Wings on stem
    the stem does not have wings on it

Wetland status

Not classified

New England distribution and conservation status

Distribution

Connecticut
present
Maine
present
Massachusetts
present
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.

Massachusetts
not applicable (S-rank: SNA)

Native to North America?

No

Sometimes confused with

Jasione montana:
leaf blades unlobed, corolla with 5 apical lobes, and fruit a capsule opening by two apical pores (vs. K. arvensis, with leaf blades lobed, corolla with 4 apical lobes, and fruit seed-like).

Synonyms

  • Scabiosa arvensis L.

Family

Caprifoliaceae

Genus

Knautia

Help

From the dichotomous key of Flora Novae Angliae

1.  Knautia arvensis (L.) Coult. E

bluebuttons. Scabiosa arvensis L. • CT, MA, ME, NH, VT. Fields, roadsides, lawns, waste areas.