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

Helianthus pauciflorus — stiff sunflower

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Facts

Stiff sunflower is a complicated, variable species with two subspecies as well as a rare stable hybrid (frequently cultivated), all of which are found in most New England states. This may pose more than the usual challenges to identification.

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
  • Rhode Island
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
  • whorled: there are three or more 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
50–270 mm
Disk flower number
more than 50
Show all characteristics

  • Flowers

    Bract cycle number
    • there are three or more cycles of bracts
    • there are two main cycles of bracts
    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 spines
    the bracts have no spines
    Bracts
    there are at least two distinct forms of bracts in different cycles
    Disk flower color
    • blue to purple
    • pink to red
    • yellow
    Disk flower number
    more than 50
    Disk flower reproductive parts
    the disk flower has both pollen- and seed-producing parts
    Disk width
    15–30 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
    Inflorescence branching (Solidago)
    NA
    Ovary beak
    there is no beak on the ovary
    Ovary cross-section
    the ovary is compressed (flattened)
    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 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
    • 16-25
    • 6-10
    Ray length
    25–35 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
    15–23 mm

  • Fruits or seeds

    Number of pappus parts
    2
    Ovary length in developed fruit
    5–6 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
    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 rhizome (a horizontal underground stem with roots growing from it)

  • 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
    • whorled: there are three or more 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
    50–270 mm
    Leaf blade shape
    • the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    • the leaf blade is linear (very narrow with more or less parallel sides)
    • 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 acuminate (tapers to a long, thin point)
    • the tip of the leaf blade is acute (sharply pointed)
    • the tip of the leaf blade is obtuse (bluntly pointed)
    Leaf blade veins
    the leaf blade has three main veins running from the base towards the tip
    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
    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
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    Specific habitat
    • man-made or disturbed habitats
    • meadows or fields

  • 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 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
    Stem internode hairs
    the stem has hairs between the nodes

Wetland status

Not classified

In New England

Distribution

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

Conservation status

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

ssp. pauciflorus

Massachusetts
not applicable (S-rank: SNA)

ssp. subrhomboideus

Massachusetts
not applicable (S-rank: SNA)

Subspecies and varieties

Subspecies pauciflorus is known from CT, MA, ME, NH, RI. Subspecies subrhomboideus is known from CT, MA, ME, NH. Clevenger and Heiser (1963) gave detailed accounts of crossing studies that suggested Helianthus ×‌laetiflorus is best treated as a hybrid (see below) and that ssp. pauciflorus may have arisose through through hybridization between H. pauciflorus ssp. subrhomboideus and H. tuberosus with later character segregation such that the stabilized entity closely resembles the former parent. Introgression with the latter species would explain the taller stems, longer leaves that are often alternate above, and longer petioles.

From Flora Novae Angliae dichotomous key

12.  Helianthus pauciflorus Nutt. E

stiff sunflower.  12a. Helianthus laetiflorus Pers. var. rigidus (Cass.) Fern.; H. rigidus (Cass.) Desf.;  12b. Helianthus laetiflorus Pers. var. subrhomboideus (Rydb.) Fern.; H. pauciflorus Nutt. var. subrhomboideus (Rydb.) Cronq.; H. rigidus (Cass.) Desf. ssp. subrhomboideus (Rydb.) Heiser; H. rigidus (Cass.) Desf. var. subrhomboideus (Rydb.) Cronq.; H. subrhomboideus Rydb. • CT, MA, ME, NH, RI; also reported from VT by Kartesz (1999), but specimens are unknown. Roadsides, fields, disturbed soil.

1a.  Reproductive stems 8–20 dm tall, with 9–15 leaf-bearing nodes below the capitulescence; leaves usually alternate on upper portion of stem, the blades oblong-lanceolate to narrow-ovate, 8–27 cm long, and acuminate at the apex … 12a. H. pauciflorus ssp. pauciflorus

1b.  Reproductive stems 5–12 dm tall, with 5–10 leaf-bearing nodes below the capitulescence; leaves usually opposite throughout the stem, the blades rhombic-ovate to narrow-lanceolate, 5–12 cm long, and acute to obtuse at the apex 
 … 12b. H. pauciflorus ssp. subrhomboideus (Rydb.) O. Spring & E. Schilling

Subspecies pauciflorus is known from CT, MA, ME, NH, RI. Subspecies subrhomboideus is known from CT, MA, ME, NH. Clevenger and Heiser (1963) gave detailed accounts of crossing studies that suggested Helianthus ×‌laetiflorus is best treated as a hybrid (see below) and that ssp. pauciflorus may have arisose through through hybridization between H. pauciflorus ssp. subrhomboideus and H. tuberosus with later character segregation such that the stabilized entity closely resembles the former parent. Introgression with the latter species would explain the taller stems, longer leaves that are often alternate above, and longer petioles.

12×15. Helianthus pauciflorus × Helianthus tuberosus → Helianthus ×‌laetiflorus Pers. is a rare hybrid sunflower that frequently 
occurs in the absence of its parents. It is known from CT, MA, ME, NH, RI, VT. It is similar to H. pauciflorus in regard to involucre characteristics and often disk corolla color (though the corollas can also be yellow), but the involucral bracts are oblong-lanceolate with an acuminate apex, are sometimes sparsely short-pubescent abaxially, and 7–12 mm long (vs. elliptic to oblong-ovate, acute to obtuse, ± glabrous abaxially, and 6–10 mm long; lanceolate with an acuminae apex, hispid abaxially, and 8.5–15 mm long in H. tuberosus). It also occasionally shows the branching tubers of H. tuberosus.

Native to North America?

Yes and no (some introduced)

Sometimes confused with

Helianthus occidentalis:
reproductive stems with mostly 3–5 nodes bearing highly reduced leaves or rarely the lower 2–4 nodes with well-formed blades, often the upper 50% of the stem lacking leaves, and plants with a basal rosette of leaves (vs. H. pauciflorus, with reproductive stems with mostly 6–15 or more leaf-bearing nodes, the blades gradually, if at all, decreasing in size upward, only the upper 25% or less of the stem lacking leaves, and plants often without a basal rosette of leaves).

Synonyms

  • Helianthus laetiflorus Pers. var. rigidus (Cass.) Fern.
  • Helianthus rigidus (Cass.) Desf.

Family

Asteraceae

Genus

Helianthus