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- Centaurea scabiosa
Centaurea scabiosa — greater knapweed
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New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
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Facts
Greater knapweed is native to Europe and occasionally escapes from cultivation in some parts of North America. Its large flowers make it a popular garden ornamental, and it is also used in traditional medicine to treat kidney problems, mouth ulcers, and to aid the healing of wounds.
Habitat
Anthropogenic (man-made or disturbed habitats), meadows and fields
Characteristics
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- New Hampshire
- Leaf type
- 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
- basal: the leaves are growing only at the base of the plant
- 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 no teeth or lobes
- the edge of the leaf blade has teeth
- Flower type in flower heads
- the flower head has disk flowers only, and lacks the strap-shaped flowers
- Ray flower color
-
- blue to purple
- pink to red
- white
- Tuft or plume on fruit
- at least a part of the plume is made up of fine bristles
- Spines on plant
- the plant has no spines
- Leaf blade length
- 100–250 mm
- Flower head width
- 50–60 mm
-
Flowers
- Bases of bract appendages
- bases of bract appendages are u-shaped, with a tiny projecting edge running across from one appendage to the next
- Bract color
- the bracts are not colored or tinged with pink, red or purple
- Bract cycle number
- there are three or more cycles of bracts
- Bract outer side hair type
-
- the bracts are hairy, with simple hairs on their outer surface
- the bracts are not hairy on their outer surface
- Bract outer side hairs
-
- the bracts are hairy on their outer surfaces
- the bracts are not hairy on their outer surfaces
- Bract shape
-
- the main bracts are lanceolate (widest above the base, then taper narrowly towards the tip)
- the main bracts are oblong (roughly rectangular but rounded at the ends)
- the main bracts are ovate (egg-shaped)
- Bract spines
- the bracts have no spines
- Bract tip color
- the tips are a different color from the center of the bract
- Bract tip extension appearance
- the projections from the bract tips have further projections from their edges, like a fringe
- Bract tip extension edge
- there are projections from the bract tips
- Bract tip orientation
- the bracts are pressed against the plant, or spreading out at the tips
- Bract tip shape
- NA
- Bract width
- 3–4
- Bracts
- there are at least two distinct forms of bracts in different cycles
- Disk flower color
-
- blue to purple
- pink to red
- white
- Disk flower lobe number
- 5
- Disk flower reproductive parts
- the disk flower has both pollen- and seed-producing parts
- Disk flower shape
- the disk flower is tube-shaped (cylindrical), or gradually widening like a funnel
- Flower head number
- each flowering stem has only one to three flower heads on it
- Flower head outer flowers
- at the outer edge of the flower head, the flowers have no enlarged lobe or strap, but are bigger than the flowers in the center of the disk
- Flower head platform
- the base has fine, short hairs on it
- Flower head platform surface
- NA
- Flower head position
- each of the flower heads is separate on its own peduncle (stalk), not clustered in groups
- Flower head profile
- the disk is flat or nearly flat across the top
- Flower head shape
- the sides of the flower head are roughly parallel, like a cylinder
- Flower head width
- 50–60 mm
- Flower type in flower heads
- the flower head has disk flowers only, and lacks the strap-shaped flowers
- Height of flower head base
- 15–25 mm
- Inflorescence branching (Solidago)
- NA
- Inflorescence shape
- the inflorescence is flat-topped in profile
- Ovary attachment
- the ovary is attached at the side near the base, rather than at the base
- Ovary beak
- there is no beak on the ovary
- Ovary cross-section
-
- the ovary has five or more corners in cross-section
- the ovary is compressed (flattened)
- Ovary hair type
- the ovary has hairs on it, but the hairs have no glands
- Ovary hairs
- the ovary has hairs on it
- Ovary profile
-
- in profile, the ovary is oblong (roughly rectangular but rounded at the ends)
- in profile, the ovary is roughly elliptical (widest in the middle, tapering to both ends)
- Ray flower color
-
- blue to purple
- pink to red
- white
- Ray flower reproductive parts
- NA
- Ray flowers
- 0
- Ray length
- 0 mm
- Reproductive system
- all the flowers on the plant contain both carpels and stamens
- Scale tip
- NA
- Smaller bracts at base of bracts
- there is no smaller, outer cycle of bracts
- Style branch number
- the style has two branches
- Width of flower head base
- 18–25 mm
-
Fruits or seeds
- Ovary length in developed fruit
- 4–5.5 mm
- Seed hair tuft color
- the pappus hairs are white or off-white
- Seed hair tuft length
- 3–6 mm
- Seed tuft type
- the pappus is made of very fine hairs or bristles
- Top of disk flower ovary
- NA
- Tuft or plume on fruit
- at least a part of the plume is made up of fine bristles
-
Glands or sap
- Leaf blade glands
- the leaf blades have glandular (translucent) dots or scales
- Sap
- the sap is clear and watery
-
Growth form
- Growth form
- the plant has one or more free-standing stems
- Plant lifespan
- the plant is perennial, it shows evidence of previous year's leaves, stems or stem bases
- Spines on plant
- the plant has no spines
- Underground organs
- there is a thickened taproot on the plant
-
Leaves
- Hairs on underside of leaf blade
- the underside of the leaf is fuzzy or hairy
- Hairs on upper side of leaf blade
-
- the upper side of the leaf is fuzzy or hairy
- the upper side of the leaf is not hairy, or has very few hairs
- Leaf arrangement
-
- alternate: there is one leaf per node along the stem
- basal: the leaves are growing only at the base of the plant
- Leaf blade base
- the leaf has a distinct petiole
- 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 has lobes, or it has both teeth and lobes
- the edge of the leaf blade has no teeth or lobes
- the edge of the leaf blade has teeth
- Leaf blade hairs
-
- the leaf blade has hairs with glands at their tips
- the leaf blade has simple hairs with no glands, and not tangled or wooly
- Leaf blade length
- 100–250 mm
- 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 tip
-
- the tip of the leaf blade is acute (sharply pointed)
- the tip of the leaf blade is obtuse (bluntly pointed)
- Leaf disposition
- the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
- Leaf spines
- there are no spines on the leaf edges
- Leaf stalk
- the leaves have leaf stalks
- Leaf tip extension
- NA
- Leaf type
- leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Specific leaf type
-
- the leaf has a row of two or more lobes on each side of the central axis
- the leaf has a row of two or more lobes on each side of the central axis, and each lobe itself has rows of lobes on each side of the lobe's central axis
-
Place
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- New Hampshire
- Specific habitat
-
- man-made or disturbed habitats
- meadows or fields
-
Stem, shoot, branch
- Leaves on stem
- there is at least one full leaf above the base of the flowering stem
- Stem internode hair direction
- the hairs point mostly upwards to outwards
- Stem internode hair type
-
- the hairs on the stem are plain, without glands or branches, and not tangled
- the stem has no hairs between the nodes
- Stem internode hairs
-
- the stem has hairs between the nodes
- the stem has no hairs between the nodes
Wetland status
Not classified
New England distribution and conservation status
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- absent
- New Hampshire
- present
- Rhode Island
- absent
- Vermont
- absent
Conservation status
None
Native to North America?
No
Sometimes confused with
- Centaurea stoebe:
- involucre 6-8 mm wide, the bracts with several prominent longitudinal veins, and fertile flowers 12-15 mm long (vs. C. scabiosa, with the involucre 18-25 mm wide, the bracts lacking prominent longitudinal veins, and fertile flowers 20-25 mm long).
Synonyms
- Acrocentron scabiosa (L.) A. & D. Löve
- Colymbada scabiosa (L.) Holub
Family
Genus
From the dichotomous key of Flora Novae Angliae
11. Centaurea scabiosa L. E
greater knapweed. Acrocentron scabiosa (L.) A. & D. Löve; Colymbada scabiosa (L.) Holub • CT, ME, NH. Roadsides, fields, waste areas.