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

Helianthus grosseserratus — saw-toothed sunflower

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Facts

Saw-toothed sunflower is native to the midwestern United States, but has spread as a weed into the Southeast, Canada, and New England. It has been used to make folk remedies including a tea to reduce fevers and loosen phlem, and the stems were used to treat malaria and burns. It occasionally forms hybrids with other sunflower (Helianthus) species.

Habitat

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

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont
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
  • opposite: there are two leaves per node along the stem
Leaf blade edges
  • 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 tubular disk flowers in the center and ray flowers, these often strap-shaped, around the periphery
Ray flower color
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
100–320 mm
Disk flower number
more than 50
Show all characteristics

  • Flowers

    Bases of bract appendages
    NA
    Bract margins
    there are fine hairs along the bract margins
    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 linear (long and very narrow)
    Bract width
    1.5–2.5
    Disk flower color
    yellow
    Disk flower lobe number
    5
    Disk flower number
    more than 50
    Disk flower reproductive parts
    the disk flower has both pollen- and seed-producing parts
    Disk width
    15–25 mm
    Flower head number
    • each flowering stem has four or more flower heads on it
    • each flowering stem has only one to three 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 shape
    the flower head is hemispherical (like the bottom half of a sphere)
    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
    Inflorescence branching (Solidago)
    NA
    Number of bracts at flower head base
    25–30
    Ovary cross-section
    the ovary is compressed (flattened)
    Ovary hair type
    the ovary has no hairs on it
    Ovary hairs
    the ovary has no hairs on it
    Peduncle length
    3–100 mm
    Ray flower color
    yellow
    Ray flower reproductive parts
    there are neither carpels nor stamens in the ray flowers
    Ray flowers
    • 11-15
    • 16-25
    Ray length
    23–40 mm
    Width of flower head base
    15–25 mm

  • Fruits or seeds

    Number of pappus parts
    2
    Ovary beak length
    3–4 mm
    Seed hair tuft bases
    NA
    Seed hair tuft color
    NA
    Seed hair tuft details
    NA
    Seed hair tuft length
    1.9–2.5 mm
    Seed hair tuft tips
    NA
    Seed hairs uniform
    NA
    Seed tuft scale number
    2
    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

    Bract resin
    the bracts have no resin or resin glands
    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
    the plant has a rhizome (a horizontal underground stem with roots growing from it)

  • Leaves

    Final leaf segment length (compound lvs only)
    0 mm
    Final leaf segment width (compound lvs only)
    0 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
    • opposite: there are two leaves per node along the stem
    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 bloom
    the underside of the leaf has no noticeable bloom
    Leaf blade edges
    • 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 tangled or woolly-looking hairs
    Leaf blade length
    100–320 mm
    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
    there is no noticeable color variation on the upper surface of the leaf
    Leaf blade tip
    the tip of the leaf blade is acuminate (tapers to a long, thin point)
    Leaf blade veins
    the leaf blade has three main veins running from the base towards the tip
    Leaf blade width
    12–90 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
    Leaf stalk length
    1–5 mm
    Leaf tip extension
    NA
    Leaf type
    leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaflet number
    0
    Specific leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets
    Teeth per side of leaf blade
    At least 0

  • Place

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

  • Scent

    Plant odor
    the plant does not have much of an odor

  • Stem, shoot, branch

    Flowering stem cross-section
    the flowering stem is circular, or with lots of small angles
    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Stem bloom
    the stem has a powdery or waxy film on it that can be rubbed away
    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 length
    At least 0 mm
    Stem internode hair type
    the stem has no hairs between the nodes
    Stem internode hairs
    the stem has no hairs between the nodes
    Stem wings
    the stem does not have wings on it

Wetland status

Usually occurs in wetlands, but occasionally in non-wetlands. (Wetland indicator code: FACW)

In New England

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)

From Flora Novae Angliae dichotomous key

6.  Helianthus grosseserratus Martens E

saw-toothed sunflower. Helianthus grosseserratus Martens var. hypoleucus Gray • CT, MA, ME, NH, VT. Roadsides, fields, disturbed soil.

4×6. Helianthus divaricatus × Helianthus grosseserratus → Helianthus ×‌divariserratus R.W. Long is an extremely rare sunflower hybrid in New England known from CT. It has a glabrous and glaucous stem bearing opposite leaves that are triple-veined (those of H. grosseserratus are pinnately veined), rounded at the base, and borne on short petioles 5–10 mm long (those of H. divaricatus truncate to broadly rounded at the base and sessile). The involucral bracts are 10–15 mm long (6–12 mm long in H. divaricatus, 10–14 mm long in H. grosseserratus).

5×6. Helianthus giganteus × Helianthus grosseserratus → Helianthus ×‌luxurians E.E. Wats. is a very rare hybrid sunflower known from CT, MA. It closely resembles its parental species. It shows ± glabrous and glaucous stems, and variably toothed leaf blades (subentire to coarsely toothed) that are usually 5–10 times as long as wide and borne on short petioles 5–10 mm long.

6×8. Helianthus grosseserratus × Helianthus maximiliani → Helianthus ×‌intermedius R.W. Long is a very rare sunflower hybrid known from MA, ME. It has sparsely strigose stems, petioles 5–15 mm long, and flat leaf blades that are strongly scabrous adaxially.

6×H. salicifolius A. Dietr. Helianthus ×‌kellermanii Britt. is a rare and local hybrid known from MA, ME. It is similar to H. grosseserratus, differing primarily in the linear 
to narrow-lanceolate principal leaf blades that are 10–20 mm wide and taper to 
the petiole and lobes of the disk corollas that are white-pubescent on the abaxial surface (vs. principal leaf blades lanceolate to narrow-ovate, 12–90 mm wide, tapering 
or rounded to the petiole, and disk corolla lobes glabrous or nearly so).

Native to North America?

Yes and no (some introduced)

Sometimes confused with

Helianthus giganteus:
lobes of the disk corollas pubescent, anther appendages red-brown to dark brown, and leaf blades strongly scabrous on the adaxial surface (vs. H. grosseserratus, with lobes of the disk corollas glabrous or glabrate, anther appendages yellow, and leaf blades slightly, if at all, scabrous on the adaxial surface).

Synonyms

  • Helianthus grosseserratus var. hypoleucus Gray

Family

Asteraceae

Genus

Helianthus