Helianthus annuus

common sunflower, annual sunflower, sunflower, wild sunflower

What does this species look like?

What does this species look like?:

Common sunflower is an annual, herbaceous plant reaching up to 9 feet tall. Its showy flowerheads consist of very small reddish, brown, or yellow flowers crowded onto a small to large disk (flowerhead center) and surrounded by a row of showier yellow, large-petaled flowers. The flowers are insect-pollinated.

Common sunflower is common in dry to moderately moist areas. It is widespread along roadsides and railroads, disturbed sites, pastures, meadows, plains, and foothills. Its many cultivars are grown for agriculture and horticulture.

Where is this species found?

States & Provinces:

AB, AK, AL, AR, AZ, BC, CA, CO, CT, DC, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MB, MD, ME, MI, MN, MO, MS, MT, NB, NC, ND, NE, NH, NJ, NM, NS, NT, NV, NY, OH, OK, ON, OR, PA, PE, PR, QC, RI, SC, SD, SK, TN, TX, UT, VA, VT, WA, WI, WV, WY

click to enlarge

Which phenophases should I observe?

Leaves	Do you see...? *Initial growth* New growth of the plant is visible after a period of no growth (winter or drought), either from above-ground buds with green tips, or new green or white shoots breaking through the soil surface. Growth is considered "initial" on each bud or shoot until the first leaf has fully unfolded. For seedlings, "initial" growth includes the presence of the one or two small, round or elongated leaves (cotyledons) before the first true leaf has unfolded. *Leaves* One or more live, fully unfolded leaves are visible on the plant. For seedlings, consider only true leaves and do not count the one or two small, round or elongated leaves (cotyledons) that are found on the stem almost immediately after the seedling germinates. Do not include fully dried or dead leaves.
Flowers	Do you see...? *Flowers or flower buds* One or more fresh open or unopened flowers or flower buds are visible on the plant. Include flower buds or inflorescences that are swelling or expanding, but do not include those that are tightly closed and not actively growing (dormant). Also do not include wilted or dried flowers. How many flowers and flower buds are present? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), simply estimate the number of flower heads, spikes or catkins and not the number of individual flowers. Less than 3;3 to 10;11 to 100;101 to 1,000;More than 1,000 More... *Open flowers* One or more open, fresh flowers are visible on the plant. Flowers are considered "open" when the reproductive parts (male stamens or female pistils) are visible between or within unfolded or open flower parts (petals, floral tubes or sepals). Do not include wilted or dried flowers. What percentage of all fresh flowers (buds plus unopened plus open) on the plant are open? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), estimate the percentage of all individual flowers that are open. Less than 5%;5-24%;25-49%;50-74%;75-94%;95% or more More...
Fruits	Do you see...? *Fruits* One or more fruits are visible on the plant. For Helianthus annuus, the fruit is very tiny and seed-like and is crowded into a large spent flower head. The seed-like fruit changes from white or light yellow-green to gray or black, often striped with white, and drops from the plant. Do not include empty flower heads that have already dropped all of their fruits. How many fruits are present? Less than 3;3 to 10;11 to 100;101 to 1,000;More than 1,000 More... *Ripe fruits* One or more ripe fruits are visible on the plant. For Helianthus annuus, a fruit is considered ripe when it has turned gray or black, often striped with white, or when it readily drops from the spent flower head when touched. Do not include empty flower heads that have already dropped all of their fruits. What percentage of all fruits (unripe plus ripe) on the plant are ripe? Less than 5%;5-24%;25-49%;50-74%;75-94%;95% or more More... *Recent fruit or seed drop* One or more mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind, or empty fruits that had long ago dropped all of their seeds but remained on the plant. How many mature fruits have dropped seeds or have completely dropped or been removed from the plant since your last visit? Less than 3;3 to 10;11 to 100;101 to 1,000;More than 1,000 More...

Leaves

Do you see...?

Initial growth
New growth of the plant is visible after a period of no growth (winter or drought), either from above-ground buds with green tips, or new green or white shoots breaking through the soil surface. Growth is considered "initial" on each bud or shoot until the first leaf has fully unfolded. For seedlings, "initial" growth includes the presence of the one or two small, round or elongated leaves (cotyledons) before the first true leaf has unfolded.

Leaves
One or more live, fully unfolded leaves are visible on the plant. For seedlings, consider only true leaves and do not count the one or two small, round or elongated leaves (cotyledons) that are found on the stem almost immediately after the seedling germinates. Do not include fully dried or dead leaves.

Flowers

Do you see...?

Flowers or flower buds
One or more fresh open or unopened flowers or flower buds are visible on the plant. Include flower buds or inflorescences that are swelling or expanding, but do not include those that are tightly closed and not actively growing (dormant). Also do not include wilted or dried flowers.

How many flowers and flower buds are present? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), simply estimate the number of flower heads, spikes or catkins and not the number of individual flowers.

Less than 3;3 to 10;11 to 100;101 to 1,000;More than 1,000

More...

Open flowers
One or more open, fresh flowers are visible on the plant. Flowers are considered "open" when the reproductive parts (male stamens or female pistils) are visible between or within unfolded or open flower parts (petals, floral tubes or sepals). Do not include wilted or dried flowers.

What percentage of all fresh flowers (buds plus unopened plus open) on the plant are open? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), estimate the percentage of all individual flowers that are open.

Less than 5%;5-24%;25-49%;50-74%;75-94%;95% or more

More...

Fruits

Do you see...?

Fruits
One or more fruits are visible on the plant. For Helianthus annuus, the fruit is very tiny and seed-like and is crowded into a large spent flower head. The seed-like fruit changes from white or light yellow-green to gray or black, often striped with white, and drops from the plant. Do not include empty flower heads that have already dropped all of their fruits.

How many fruits are present?

Less than 3;3 to 10;11 to 100;101 to 1,000;More than 1,000

More...

Ripe fruits
One or more ripe fruits are visible on the plant. For Helianthus annuus, a fruit is considered ripe when it has turned gray or black, often striped with white, or when it readily drops from the spent flower head when touched. Do not include empty flower heads that have already dropped all of their fruits.

What percentage of all fruits (unripe plus ripe) on the plant are ripe?

Less than 5%;5-24%;25-49%;50-74%;75-94%;95% or more

More...

Recent fruit or seed drop
One or more mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind, or empty fruits that had long ago dropped all of their seeds but remained on the plant.

How many mature fruits have dropped seeds or have completely dropped or been removed from the plant since your last visit?

Less than 3;3 to 10;11 to 100;101 to 1,000;More than 1,000

More...

USDA PLANTS profile for common sunflower (USDA Symbol: HEAN3)
ITIS information for common sunflower (ITIS TSN: 36616)

Acknowledgments

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Helianthus annuus