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• Dichotomous Key
• Asteraceae
• Asteraceae Group 5
• Jacobaea
• Jacobaea vulgaris

Jacobaea vulgaris — tansy ragwort

Facts

Tansy ragwort is considered a noxious weed in California and the Northwest, but it is rare in New England. It was first seen in seaports in the early 1900's, and is easily spread in contaminated hay. It is a cause of toxins in milk as cattle do not avoid it.

Habitat

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

Characteristics

• Flowers

  Bract cycle number

  there is one main cycle 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 separation

  the bracts appear completely unconnected to one another on all flower heads

  Bract shape

  the main bracts are ovate (egg-shaped)

  Bract spines

  the bracts have no spines

  Bract texture

  the bracts appear thin, flexible and nearly translucent

  Bract tip color

  the tips are a different color from the center of the bract

  Bract tip shape

  the tips of the bracts acute (have a sharp point)

  Bract width

  At least 1.2

  Bracts

  the bracts in separate cycles are similar or gradually changing from the outer to inner cycles

  Disk flower color

  yellow

  Disk flower lobe number

  5

  Disk flower number

  • 1-5
  • more than 50

  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
  • the disk flower looks different from the choices given

  Disk width

  7–10 mm

  Flower head number

  each flowering stem has four or more flower heads on it

  Flower head outer flowers

  at the outer edge of the flower head, each flower has a single enlarged lobe or strap

  Flower head platform

  the base has no bristles or papery scales

  Flower head profile

  • the disk is flat or nearly flat across the top
  • the disk is rounded across the top

  Flower head shape

  the flower head is shaped like a cone with the point up

  Flower head width

  15–20 mm

  Flower type in flower heads

  • the flower head has disk flowers only, and lacks the strap-shaped flowers
  • the flower head has ray flowers only, meaning all of the individual flowers of the flower head have a strap-shaped ray, which may or may not have teeth at the very tip of the ray

  Height of flower head base

  3–5 mm

  Inflorescence branching (Solidago)

  NA

  Inflorescence shape

  the inflorescence is flat-topped in profile

  Inflorescence stem

  hairs are present on the stem of the inflorescence

  Number of bracts at flower head base

  12–14

  Ovary cross-section

  the ovary has five or more corners in cross-section

  Ovary hair type

  • the ovary has hairs on it, but the hairs have no glands
  • the ovary has no hairs on it

  Ovary hairs

  • the ovary has hairs on it
  • the ovary has no hairs on it

  Ovary lines or ribs

  there are four to six lines or ribs visible on the ovary

  Ovary profile

  in profile, the ovary is oblong (roughly rectangular but rounded at the ends)

  Ray flower color

  yellow

  Ray flower reproductive parts

  the ray flowers have carpels or stamens, but not both

  Ray flowers

  • 0
  • 11-15

  Ray length

  4–8 mm

  Reproductive system

  all the flowers on the plant contain both carpels and stamens

  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

  5–40 mm

• Fruits or seeds

  Number of pappus parts

  11 or more

  Ovary length in developed fruit

  2–3 mm

  Seed hair tuft color

  the pappus hairs are white or off-white

  Seed hair tuft details

  • the pappus hairs are hooked or barbed
  • the pappus hairs are smooth and plain

  Seed hair tuft tips

  the pappus hairs are slender

  Seed tuft type

  the pappus is made of very fine hairs or bristles

  Tuft or plume on fruit

  at least a part of the plume is made up of fine bristles

• 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

  Leaf arrangement

  alternate: there is one leaf per node along the stem

  Leaf blade base

  • the leaf has a distinct petiole
  • the leaf has no 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 bloom

  the underside of the leaf has no noticeable bloom

  Leaf blade edges

  the edge of the leaf blade has teeth

  Leaf blade hairs

  the leaf blade has tangled or woolly-looking hairs

  Leaf blade length

  40–300 mm

  Leaf blade shape

  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 obtuse (bluntly pointed)
  • the tip of the leaf blade is rounded, with no point

  Leaf blade veins

  the leaf blade has one main vein running from the base towards the tip

  Leaf blade width

  10–120 mm

  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
  • the leaves have no leaf stalks, but attach directly to the stem

  Leaf type

  leaves are simple (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, and each lobe itself has rows of lobes on each side of the lobe's central axis
  • the leaf has lobes that themselves have lobes, and these secondary lobes also have lobes; there may be more than three levels of lobes

• Place

  Habitat

  terrestrial

  New England state

  • Maine
  • Massachusetts

  Specific habitat

  • man-made or disturbed habitats
  • meadows or fields

• Scent

  Plant odor

  the plant has an unpleasant or repellant odor

• 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

  • at least some of the hairs on the stem are tangled, matted or woolly
  • the stem has no hairs between the nodes

  Stem internode hairs

  the stem has hairs between the nodes

Wetland status

Occurs only in non-wetlands. (Wetland indicator code: UPL)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae