Helianthus microcephalus Torr. & Gray

small-headed sunflower

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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

The small-headed sunflower, true to its name, has smaller flower heads than the other sunflower species, an inch or less in diameter. Its natural range does not extend into New England, but it is often grown in gardens.

Habitat

Anthropogenic (man-made or disturbed habitats)

Characteristics

Habitat
terrestrial
New England state
Connecticut
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
70–200 mm
Disk flower number
  • 11-20
  • 21-50
Show All Characteristics
  • Flowers
    Bract cycle number
    • there are three or more cycles of bracts
    • there are two main cycles of bracts
    Bract inner side hairs
    the bracts are not hairy on their inner surfaces
    Bract margins
    there are fine hairs along the bract margins
    Bract outer side hair type
    the bracts are not hairy on their outer surface
    Bract outer side hairs
    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)
    Bract tip orientation
    the bracts are pressed against the plant, or spreading out at the tips
    Bract tip shape
    • the tips of the bracts acute (have a sharp point)
    • the tips of the bracts are acuminate (tapered to a narrow point)
    Bracts
    the bracts in separate cycles are similar or gradually changing from the outer to inner cycles
    Disk flower color
    yellow
    Disk flower number
    • 11-20
    • 21-50
    Disk flower reproductive parts
    the disk flower has both pollen- and seed-producing parts
    Disk width
    4–10 mm
    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 profile
    the disk is rounded across the top
    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
    7–10 mm
    Inflorescence branching (Solidago)
    NA
    Ovary beak
    there is no beak on the ovary
    Ovary cross-section
    the ovary is compressed (flattened)
    Ovary hairs
    • the ovary has hairs on it
    • the ovary has no hairs on it
    Ovary profile
    in profile, the ovary is another shape
    Ray flower color
    yellow
    Ray flower reproductive parts
    there are neither carpels nor stamens in the ray flowers
    Ray flowers
    • 11-15
    • 6-10
    Ray length
    10–15 mm
    Reproductive system
    some of the flowers on the plant have only carpels or stamens, while others have both carpels and stamens
    Style branch number
    the style has two branches
    Width of flower head base
    6–13 mm
  • Fruits or seeds
    Number of pappus parts
    2
    Ovary length in developed fruit
    3.5–4.2 mm
    Seed hair tuft bases
    NA
    Seed hair tuft color
    NA
    Seed hair tuft details
    NA
    Seed hair tuft length
    1–5 mm
    Seed hair tuft tips
    NA
    Seed hairs uniform
    NA
    Seed tuft scale number
    2–6
    Seed tuft type
    • the pappus is made of flat scales that are not split or frayed at the tips
    • the pappus is made of stiff, tapering bristles
    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
  • 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 caudex (the root mass is firm and hardened at the top)
    • the plant has a rhizome (a horizontal underground stem with roots growing from it)
    • there are only slender roots 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
    • 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 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 simple hairs with no glands, and not tangled or wooly
    Leaf blade length
    70–200 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 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
    10–60 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
    5–25 mm
    Leaf type
    leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Specific leaf type
    the leaves are simple (i.e., lobed or unlobed but not separated into leaflets
  • Place
    Habitat
    terrestrial
    New England state
    Connecticut
    Specific habitat
    man-made or disturbed habitats
  • 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
    NA
    Stem internode hair type
    the stem has no hairs between the nodes
    Stem internode hairs
    the stem has no hairs between the nodes

Wetland Status

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

New England Distribution and Conservation Status

Distribution

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

Conservation Status

None

Native to North America?

Yes and no (some introduced)

Sometimes Confused With

Helianthus decapetalus:
disk 15–25 mm wide and capitula with 8–12 ray flowers (vs. H. microcephalus, with the disk 4–10 mm wide and capitula with 5–8 ray flowers).

Family

Asteraceae

Genus

Helianthus

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Information from Dichotomous Key of Flora Novae Angliae

9.  Helianthus microcephalus Torr. & Gray E

small-headed sunflower. CT. Gardens, waste areas.