Rhododendron macrophyllum

This has been the official flower of Washington State since 1892.  Rhododendron macrophyllum was chosen in a state-wide vote only open to women before the 1893 Chicago World Fair.  The leaves, flowers and nectar of this species can be toxic to humans and livestock.   Honey made from the floral nectar has also been shown to be toxic.
Photo Credit: © Randy Smith via Wikimedia Commons
Rhododendron macrophyllum
Common Name: Pacific rhododendron
Plant Functional Group: Evergreen broadleaf
Class > Order > Family: Magnoliopsida > Ericales > Ericaceae
What does the species look like?

This species is a broadleaf evergreen shrub with grayish-brown bark that can be up to 4 meters tall. The thick leathery leaves are dark green and whorled at the tip of branches. Leaves have an elliptical shape and are 7 to 15 centimeters long by 3 to 7 centimeters wide. The bell shaped flowers are light to rose pink and 2 to 4 centimeters long. They are found in large loose clusters at the end of the branches. The fruit is a small brown five part capsule.

Rhododendron macrophyllum is found along Pacific coast, between Monterey County and British Columbia, in moist coniferous forests at elevations less than 1100 meters.  It also thrives in disturbed habitats.
Where is the species found?
States & Provinces
BC, CA, OR, WA
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.
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
Young leaves
One or more young, unfolded leaves are visible on the plant. A leaf is considered "young" and "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, but before the leaf has reached full size or turned the darker green color or tougher texture of mature leaves on the plant. Do not include fully dried or dead leaves.

How many young leaves are present?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000
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
Fruits Fruits
One or more fruits are visible on the plant. For Rhododendron macrophyllum, the fruit is a woody capsule that changes from green to rusty brown and splits open to expose the seeds. Do not include empty capsules that have already dropped all of their seeds.
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 Rhododendron macrophyllum, a fruit is considered ripe when it has turned rusty brown and has split open to expose the seeds. Do not include empty capsules that have already dropped all of their seeds.
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?

There is currently no photoguide available for this species. If you'd like help us create one, use the guidance document and species template provided here. Then send it via email to education@usanpn.org when it is complete.

USDA PLANTS profile for Pacific rhododendron (USDA Symbol: RHMA3 )