- You are here:
- Dichotomous Key
- Asteraceae
- Asteraceae Group 6
- Helianthus
- Helianthus decapetalus
Helianthus decapetalus — thin-leaved sunflower
Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.
Facts
The seeds of thin-leaved sunflower are eaten by gamebirds and songbirds. Muskrats eat the leaves and stems and use the stems in the construction of their lodges. The Meskwaki applied a poultice of the macerated roots to persistent sores.
Habitat
Floodplain (river or stream floodplains), forest edges, forests
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
Found this plant? Take a photo and post a sighting.
Characteristics
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- 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 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
- 70–210 mm
- Disk flower number
- 21-50
-
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 tip shape
- the tips of the bracts are acuminate (tapered to a narrow point)
- Bract width
- 2–3
- Disk flower color
- yellow
- Disk flower lobe number
- 5
- Disk flower number
- 21-50
- Disk flower reproductive parts
- the disk flower has both pollen- and seed-producing parts
- Disk width
- 10–20 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
- 20–25
- Ovary cross-section
- the ovary is compressed (flattened)
- Peduncle length
- 20–120 mm
- 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
- 20–25 mm
- Width of flower head base
- 12–25 mm
-
Fruits or seeds
- Number of pappus parts
- 2
- Ovary length in developed fruit
- 3.5–5 mm
- Seed hair tuft bases
- NA
- Seed hair tuft color
- NA
- Seed hair tuft details
- NA
- Seed hair tuft length
- 3–4 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
- 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
- the base of the leaf blade is rounded
- the base of the leaf blade is truncate (ends abruptly in a more or less straight line as though cut off)
- 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 length
- 70–210 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)
- the tip of the leaf blade is rounded, with no point
- Leaf blade veins
- the leaf blade has three main veins running from the base towards the tip
- Leaf blade width
- 40–100 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
- 15–60 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
-
Place
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- edges of forests
- forests
- river or stream floodplains
-
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
- there is no powdery or waxy film on the stem
- Stem internode hair direction
- NA
- Stem internode hair length
- 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 non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)
In New England
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- present
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- fairly widespread (S-rank: S4)
From Flora Novae Angliae dichotomous key
3. Helianthus decapetalus L. N
thin-leaved sunflower. Helianthus tracheliifolius P. Mill. • CT, MA, ME, NH, RI, VT. Riparian forests, mesic, deciduous forests, forest edges.
Native to North America?
Yes
Sometimes confused with
- Helianthus strumosus:
- involucral bracts at base of flower head ascending, not exceeding the disk of the flower head and leaf stalks 5-30 mm long (vs. H. decapetalus, with the involucral bracts at base of flower head spreading, much longer than the disk of the flower head and leaf stalks 15-60 mm long).
- Helianthus tuberosus:
- stems evidently hairy and without a bloom and rhizomes ending in thickened tubers (vs. H. decapetalus, with stems without hairs or with very few hairs and with a whitish bloom and rhizomes not ending in thickened tubers).
Synonyms
- Helianthus tracheliifolius P. Mill.