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The Redbud Phenology Project

Project Background

The Redbud Phenology Project logoOne of the most iconic native North American trees is the eastern redbud (Cercis canadensis). This tree is one of the earlier flowering forest trees in the spring. Because it is beautiful when in flower, it has become a widespread ornamental tree in the US and elsewhere around the world.

New for 2023: we have added western redbud (Cercis occidentalis) to this campaign to better understand the phenology of redbuds in the western US! 

We are interested in answering the following questions: 1) When do redbud trees flower and fruit across the tree's range? 2) How does the timing of these events vary across geography and elevation? 3) Has the timing of flowering and fruiting advanced in recent years?

Join us!

We welcome your reports of what your redbud tree is doing throughout the season. We will compare these observations to historical records of flowering and fruiting contributed to herbaria in the eastern U.S. 

How to Participate

1. Join Nature's Notebook. If you haven't already, create a Nature's Notebook account. Take the Observer Certification Course at if you need more details on getting started. You can set up a phenology monitoring site in your backyard or another location you frequent.

For further assistance: 

2. Take observations. For this effort, we are seeking observations on the following life cycle stages:

Phenophase Definition Photo (click to enlarge)
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. Redbud Flowers or flower buds, Photo: Agnes Monkelbaan via Wikimedia Commons, CC BY-SA 4.0
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.  Redbud Open flowers, Photo: Fredlyfish4 via Wikimedia Commons, CC BY-SA 4.0
Fruits One or more fruits are visible on the plant. For Cercis canadensis, the fruit is a pod that changes from green to purplish to dark brown and, over time, splits open to expose the seeds. Do not include empty pods that have already dropped all of their seeds. Redbud Fruits, Photo: SEWilco via Wikimedia Commons, CC BY-SA 3.0 
Ripe fruits One or more ripe fruits are visible on the plant. For Cercis canadensis, a fruit is considered ripe when it has turned dark brown. Do not include empty pods that have already dropped all of their seeds.  Redbud Ripe fruits, Photo: JDMcGreg via Wikimedia Commons, CC BY-SA 3.0
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.  

3. Report your observations. As you collect data during the season, log into your Nature's Notebook account and enter the observation data you record. You can also use our smartphone apps to submit your observations.

Download the eastern redbud datasheet

Questions about this effort? Contact Dr. Jorge Santiago-Blay, National Museum of Natural History and Penn State York.