Acer rubrum

This is one of the species in our North American forests that provides brilliant autumn coloring. The sap from this plant is suitable for syrup production, though the tapping season is shorter than sugar maple because of its earlier flowering.

Photo Credit: © Elaine Haug, USDA-NRCS PLANTS Database. Courtesy of Smithsonian Institution, Dept. of Systematic Biology, Botany.

Acer rubrum

Common Name: red maple

Plant Functional Group: Deciduous broadleaf

Class > Order > Family: Magnoliopsida > Sapindales > Sapindaceae

What does the species look like?

Red maple is a deciduous tree growing 30 to 90 feet tall. Its tiny, usually red, male and female flowers mostly occur separately on the same tree but occasionally can occur on different trees.

Red maple is often found in swamps and on moist soils, but can also thrive in drier habitats. It occurs on moist soils along stream banks, and in swamps, moist to drier woodlands, and occasionally on dry rocky hillsides and sand dunes. It is moderately shade-tolerant.

Where is the species found?

States & Provinces

AL, AR, CT, DC, DE, FL, GA, IA, IL, IN, KY, LA, MA, MD, ME, MI, MN, MO, MS, NB, NC, NH, NJ, NL, NS, NY, OH, OK, ON, PA, PE, QC, RI, SC, TN, TX, VA, VT, WI, WV

Special Considerations for Observing

If drought seems to be the cause of leaf color or fall for a plant, please make a comment about it for that observation.

This species has separate male and female flowers. If you know whether the flowers you are observing are male or female (or both), please make a comment about it for that observation.

Note that individuals of this species with only male flowers will not produce fruit.

Which phenophases should I observe?

	Do you see...?
Leaves	Breaking leaf buds One or more breaking leaf buds are visible on the plant. A leaf bud is considered "breaking" once a green leaf tip is visible at the end of the bud, but before the first leaf from the bud has unfolded to expose the leaf base at its point of attachment to the leaf stalk (petiole) or stem. For Acer rubrum, leaf tips may appear reddish. More... How many buds are breaking? Less than 3 3 to 10 11 to 100 101 to 1,000 1,001 to 10,000 More than 10,000
	Leaves One or more live, unfolded leaves are visible on the plant. A leaf is considered "unfolded" once its entire length has emerged from a breaking bud, stem node or growing stem tip, so that the leaf base is visible at its point of attachment to the leaf stalk (petiole) or stem. Do not include fully dried or dead leaves. More... What percentage of the potential canopy space is full with leaves? Ignore dead branches in your estimate of potential canopy space. Less than 5% 5-24% 25-49% 50-74% 75-94% 95% or more
	Increasing leaf size A majority of leaves on the plant have not yet reached their full size and are still growing larger. Do not include new leaves that continue to emerge at the ends of elongating stems throughout the growing season. More... What percentage of full size are most leaves? Less than 25% 25-49% 50-74% 75-94% 95% or more
	Colored leaves One or more leaves show some of their typical late-season color, or yellow or brown due to drought or other stresses. Do not include small spots of color due to minor leaf damage, or dieback on branches that have broken. Do not include fully dried or dead leaves that remain on the plant. More... What percentage of the potential canopy space is full with non-green leaf color? Ignore dead branches in your estimate of potential canopy space. Less than 5% 5-24% 25-49% 50-74% 75-94% 95% or more
	Falling leaves One or more leaves with typical late-season color, or yellow or brown due to other stresses, are falling or have recently fallen from the plant. Do not include fully dried or dead leaves that remain on the plant for many days before falling. More...
Flowers	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. More... 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 1,001 to 10,000 More than 10,000
	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. More... 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
	Pollen release One or more flowers on the plant release visible pollen grains when gently shaken or blown into your palm or onto a dark surface. More... How much pollen is released? Little: Only a few grains are released. Some: Many grains are released. Lots: A layer of pollen covers your palm, or a cloud of pollen can be seen in the air when the wind blows
Fruits	Fruits One or more fruits are visible on the plant. For Acer rubrum, the fruit is two joined seeds in a "V" shape, each seed having a wing, that changes from green or red to tan or brownish and drops from the plant. More... How many fruits are present? Less than 3 3 to 10 11 to 100 101 to 1,000 1,001 to 10,000 More than 10,000
	Ripe fruits One or more ripe fruits are visible on the plant. For Acer rubrum, a fruit is considered ripe when it has turned tan or brownish and readily drops from the plant when touched. More... 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
	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. More... 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 1,001 to 10,000 More than 10,000

What do these phenophases look like?

The following Phenophase Photo Guides for this species have been vetted for accuracy by the USA-NPN National Coordinating Office. Most photo guides are developed for a particular local or regional monitoring effort, and some of the content may not apply to your effort or your region. However, we make them available to provide as much help as they may in illustrating phenophases for this species. If you have high quality phenophase photos that you are willing to share with us, please visit the Phenophase Photo Guidelines page.

Be aware there is variation from individual to individual within a species, especially across different regions, so your plant may not look exactly like the one pictured.

Since they do not always include complete definitions for the species, use these photo guides ONLY in conjunction with the official Nature's Notebook phenophase defintions included in the table above, in the phenophase definition sheet that downloads with the datasheet, or in the Observe screen in the mobile app.

Scarsdale Public Schools CHOICE Program: Acer rubrum

ITIS information for red maple (ITIS TSN: 28728 )

USDA PLANTS profile for red maple (USDA Symbol: ACRU )

Acer rubrum

Nature's Notebook

Phenology Data

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