Parthenium hysterophorus L.

Santa Maria feverfew

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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 About

Santa Maria feverfew is probably native to Mexico, Central America and parts of South America, but it has expanded its range around the world. It has become one of the most feared weeds on earth due to its health effects on humans and cattle (asthma, bronchits, dermatitis, and hay fever), as well as its allellopathic (toxic, growth-inhibiting) effects on other plants, including crops. Nevertheless, it is often used in herbal medicine to treat conditions including tuberculosis, dysentery and ague, and animal studies have shown antitumor activity in mice. It is uncommon in New England.

Habitat

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

Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Massachusetts
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
Flower type in flower heads
the flower head has tubular disk flowers in the center and ray flowers, these often strap-shaped, around the periphery
Ray flower color
  • white
  • yellow
Tuft or plume on fruit
there is no plume, or the plume is made up of scales, awns, a crown, or a rim
Spines on plant
the plant has no spines
Leaf blade length
30–180 mm
Flower head width
4–5 mm
Disk flower number
  • 11-20
  • 21-50
  • more than 50
Show All Characteristics
  • Flowers
    Bract cycle number
    there are two main cycles of bracts
    Bract outer side hairs
    the bracts are not hairy on their outer surfaces
    Bract separation
    the bracts appear completely unconnected to one another on all flower heads
    Bract texture
    • the bracts appear thin, flexible and nearly translucent
    • the bracts have a similar texture to a leaf
    Disk flower color
    • white
    • yellow
    Disk flower lobe number
    5
    Disk flower number
    • 11-20
    • 21-50
    • more than 50
    Disk flower reproductive parts
    the disk flower has either only pollen- or only seed-producing parts
    Disk flower shape
    the disk flower is tube-shaped (cylindrical), or gradually widening like a funnel
    Disk width
    3–5 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 papery scales on it
    Flower head position
    some or all the flower heads are grouped in clusters of two or more
    Flower head profile
    • the disk is conical across the top
    • the disk is flat or nearly flat across the top
    Flower head shape
    the flower head is hemispherical (like the bottom half of a sphere)
    Flower head width
    4–5 mm
    Flower type in flower heads
    the flower head has tubular disk flowers in the center and ray flowers, these often strap-shaped, around the periphery
    Height of flower head base
    3–12 mm
    Inflorescence branching (Solidago)
    NA
    Inflorescence shape
    • the inflorescence is flat-topped in profile
    • the inflorescence is not flat-topped but appears rounded, with some flower heads distinctly higher than others
    Number of bracts at flower head base
    10–16
    Ovary cross-section
    • the ovary has five or more corners in cross-section
    • the ovary is compressed (flattened)
    Ovary profile
    • in profile, the ovary is another shape
    • in profile, the ovary is lance-shaped, but widest above the middle
    • in profile, the ovary is roughly egg-shaped, but widest above the middle
    Peduncle hairs
    the peduncles are hairy
    Peduncle length
    1–15 mm
    Peduncle orientation
    the flower heads are held upright, or slightly angled outwards
    Ray flower color
    • white
    • yellow
    Ray flower reproductive parts
    the ray flowers have carpels or stamens, but not both
    Ray flowers
    6-10
    Ray length
    2.5–4 mm
    Reproductive system
    the flowers on the plant may have either carpels or stamens, but always in separate flowers
    Style branch number
    the style has one branch
    Swelling at base of flower head
    the peduncles are not swollen, or only slightly
    Width of flower head base
    3–12 mm
  • Fruits or seeds
    Dispersal unit
    the seeds fall off or are dispersed separately from one another
    Number of pappus parts
    • 0
    • 3
    Ovary length in developed fruit
    1.5–3.5 mm
    Seed hair tuft bases
    NA
    Seed hair tuft color
    NA
    Seed hair tuft details
    NA
    Seed hair tuft length
    0.5–1 mm
    Seed hair tuft tips
    NA
    Seed hairs uniform
    NA
    Seed tuft scale number
    0–3
    Seed tuft type
    the pappus is made of flat scales that are not split or frayed at the tips
    Top of disk flower ovary
    NA
    Tuft or plume on fruit
    there is no plume, or the plume is made up of scales, awns, a crown, or a rim
  • 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 annual, it lacks evidence of previous years' growth
    Spines on plant
    the plant has no spines
    Underground organs
    there are only slender roots on the plant
  • Leaves
    Final leaf segment length (compound lvs only)
    3–50 mm
    Final leaf segment width (compound lvs only)
    2–15 mm
    Hairs on underside of leaf blade
    the underside of the leaf is fuzzy or hairy
    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
    • 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 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
    Leaf blade hairs
    the leaf blade has simple hairs with no glands, and not tangled or wooly
    Leaf blade length
    30–180 mm
    Leaf blade shape
    the leaf blade is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
    Leaf blade veins
    the leaf blade has one main vein running from the base towards the tip
    Leaf blade width
    10–90 mm
    Leaf disposition
    • the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
    • the lower leaves are larger, toothier, and/or on longer stalks than the upper leaves
    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 length
    Up to 20 mm
    Leaf type
    leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaflet number
    0
    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
    • Massachusetts
    Specific habitat
    • man-made or disturbed habitats
    • meadows or fields
  • Stem, shoot, branch
    Stem internode hair direction
    the hairs are pressed flat against the plant, pointing either towards the plant's tip or towards it's base
    Stem internode hair type
    at least some of the hairs on the stem are tangled, matted or woolly
    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

Distribution

Connecticut
present
Maine
absent
Massachusetts
present
New Hampshire
absent
Rhode Island
absent
Vermont
absent

Conservation Status

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

Massachusetts
unranked (S-rank: SNR)

Native to North America?

No

Sometimes Confused With

Parthenium integrifolium

Synonyms

  • Parthenium lobatum Buckl.

Family

Asteraceae

Genus

Parthenium

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Information from Dichotomous Key of Flora Novae Angliae

1.  Parthenium hysterophorus L. E

Santa Maria feverfew. Parthenium lobatum Buckl. • CT, MA. Fields, roadsides, waste areas.