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Cloned Dogwoods

You're invited to participate in the Cloned Plants Project by obtaining a cloned Cloned Plants Program logo dogwood and reporting phenology observations via Nature's Notebook. You can also participate by tracking a native flowering dogwood that is already established in your yard.

Why Clones?

dogwood flowersA maple tree in New York blooms later than a maple tree in Georgia. Why? Is it that both trees bloom when it's been warmer than 40 degrees Farenheit for 3 weeks? Or are there genetic differences between the trees? One way to tease these influences apart is by planting genetically identical plants, or clones, in different locations, and then to observe when they leaf out and flower. When observations are made on cloned plants, you can know with confidence that differences in the timing of phenological events between different individuals is due to differences in local environmental conditions.

Volunteers have been tracking cloned lilacs for over 50 years, and these observations have been invaluable for documenting how plants are responding to a variable and changing climate. However, lilacs don't grow very well in the southernmost parts of the US. A dogwood was recently cloned for distribution in southeastern states to address part of this data gap, and Nature's Notebook participants began submitting observations in 2013.

Consider contributing to this valuable effort by tracking a cloned dogwood (Cornus florida 'Appalachian Spring'). View the map to find out whether dogwoods grow where you live. To acquire a cloned dogwood plant, view the list of local cloned dogwood distributors, or inquire at your local nursery. We are also interested in observations of cloned lilacs; if you live outside of the dogwood distribution, a cloned lilac might be best for you. See what volunteers' observations of cloned dogwoods are revealing.

How to participate...

1. Mark your cloned plants.

If you received cloned dogwoods from us prevously, check our guide on dogwood planting and care.

If you prefer to track plants which are already established at your site, we also welcome observations on the native flowering dogwood (Cornus florida)

2. Join Nature's Notebook. If you haven't already, create a Nature's Notebook account. See our specifics of observing if you need more details on getting started. Make sure you register your dogwoods as the clone Cornus florida 'Appalachian Spring' when adding the plants to your site. 

3. Observe your plant(s). Report what you see (yes/no/not sure) on your plant periodically following the instructions for cloned dogwoods. We encourage you to observe your plant(s) 2-4 times a week, especially in the spring, when things are changing rapidly. However, we welcome any observations you can contribute.

We are especially interested in the following phenophases, although you are welcome to track all of the phenophases for this species. We have also included some photos to help you identify some of the more tricky phenophases:

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 stalk (petiole) or leaf base. Breaking leaf bud, Photo: Josh Sayers
Leaves One or more live, unfolded leaves are visible on the plant. A leaf is considered "unfolded" once its entire length has emerged from the breaking bud so that the leaf stalk (petiole) or leaf base is visible at its point of attachment to the stem. Do not include fully dried or dead leaves.  
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.  Increasing leaf size, Photo: CJ Tsai, Dogwood Genome Project
Flower buds One or more fresh open or unopened flowers or flower buds are visible on the plant. Include flower buds that are still developing, but do not include wilted or dried flowers. As soon as the overwintering flower buds begin to swell, you can start reporting "yes" to flowers or flower buds Flower buds, Photo: Dennis Brown, Wikimedia Commons
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. For Cornus florida 'Appalachian Spring', ignore the four large, white bracts and watch for the opening of the small flowers in the center of the bracts'. Remember, you should continue to report "yes" to flowers or flower buds (above) when you report "yes" to open flowers. Open flowers, Photo: Dcrjsr, Wikimedia Commons

 

How do I tell a leaf bud from a flower bud? Leaf buds (left photo) and flower buds (right photo) can be tricky to identify. If you think you have misidentified a flower or leaf bud, you can correct your submitted observations. Learn more here. Also, remember that the "flowers" you are looking for are actually the small yellow/green flowers inside the large white bracts. In dogwoods, flower buds generally start to open before leaf buds. 

Leaf buds, Photo: S.Seiberling UNC Herbarium Flower buds, Photo: Derek Ramsey, Wikimedia Commons

 

4. Report your observations. Periodically log into your Nature's Notebook account and transfer your observations from your paper data sheet into the online reporting system. Alternatively, you can enter your observations directly using our Android or iPhone smartphone and tablet apps.


2018 Results from the cloned and flowering dogwood campaign

Over the last five years of this campaign, observers reported nearly 150,000 records on dogwoods, capturing nearly a thousand onsets of flowers or flower buds and thousand onsets of breaking leaf buds between 2014 and 2018. The highest number of individual trees were observed in 2017.

Dogwood campaign growth 2014-18

Observers submitted data at 126 sites this year on cloned and native flowering dogwoods.

Sites reporting on native flowering dogwood (represented by blue) and cloned dogwood (Appalachian Spring, represented by yellow) in 2018. Darker colors represent sites with more observations.

Dogwood campaign map of sites 2018

This year, observers reported flowers or flower buds slightly later than last year for both native flowering dogwoods and cloned dogwoods.

Dogwood flowering 2018 vs 2017

If we take a closer look at the reports for flowers or flower buds, we can see that the proportion of individual cloned dogwoods with "yes" records was higher earlier in the year in 2017 than in 2018. This may be due to the early spring of 2017 over much of the country.

Cloned dogwood flowering 2017 and 2018

Observations of dogwood flowering tended to be earlier in the south and California than in the Midwest and Northeast.

Dogwood flowering map 2018

This year, observers reported breaking leaf buds earlier than last year for native flowering dogwoods, but later than last year for cloned dogwoods.

Dogwood breaking leaf buds 2018 vs 2017

If we take a closer look at the proportion of cloned dogwoods for which observers reported a "yes" for breaking leaf buds, we see that while the first "yes" reports were earlier for 2018, the peak in reports of breaking leaf buds was earlier in 2017 than in 2018. This follows the pattern of flowers or flower buds, where 2018 was later than 2017.

Cloned dogwood breaking leaf buds 2017 and 2018

Observations of dogwood breaking leaf buds tended to be earlier in California and parts of the Southeast than in the Northeast and Midwest.

Dogwood breaking leaf bud map 2018

We hope that you join us again next year to keep learning about your dogwoods and adding to this rich dataset. Your reports will help us to continue to understand how local environmental conditions influence the timing of flowering and leafing in dogwoods and to develop models to predict these seasonal events in the future.

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