Beauty and Significance – the PCN Plant Consortium
The Peony Garden at the Nichols Arboretum is simultaneously three things:
a beloved destination for generations of peony lovers
a definitive reference collection, internationally recognized within a network of sister-gardens
a conservation model for other historic cultivar collections based on new research methods and perspectives
Serving all three capacities at the same time is what makes the Peony Garden so distinctive. Let’s look at each role and how together they set an exciting future.
A beloved destination
Every peony is beautiful by itself. When you have nearly 800 plants the many story-themes for arranging them are all appealing. To prioritize the immersive experience we’ve retained the original design of 27 beds with all 789 planting-spots aligned in one master-grid. We’ve intentionally kept broad paths and we seasonally install picture-labels (year-round online) to allow exact identification of every plant. However, we’ve made the intentional decision to focus the 27 beds on historic herbaceous peonies. These are peonies introduced to gardens before 1950 (most before 1930). Fortunately, these are often fragrant – individually and even more complexly so in such an extensive display. We’ve taken 5 beds and replanted each of these with a theme – while keeping the master grid and historic restriction. These themes are culture-of-origin, types of floral forms, and wild species and their simple hybrids.
Ever since the garden was first mapped in the 1920s, the slopes above the square beds have been designated for tree peonies. These have been added, mostly since 2010. In addition, no one in the 1920s could have imagined the desired-for-centuries hybrids between herbaceous and tree peonies would be successfully accomplished in the next generation. In 1948, Mr. Itoh of Japan, showed how these “intersectional” peonies could be bred, and “the rest is history.” A selection of intersectional peonies are in their own bed showing their broader color spectrum, and enriching our story-telling capacity across cultures and times.
Together, all the beds of peonies – in the bloom order of tree, intersectional, and herbaceous – harmonize into an immersive experience even if our guest cares nothing about the next two components that make our garden so significant in national and international contexts. Our success depends on the peony garden being so beautiful that it is always a destination – the recurrent huge and diverse audience shows there is ongoing public engagement and meaning.
In our years ahead, we’ll be increasing both the kinds of stories our peonies tell, and the range of voices and media in which it’s done. Yes, that will mean more visitors – on-site and digital – and that’s good!
A definitive reference collection
A living reference collection as ours manages ‘gold-standard’ specimens – their identity is authenticated so well that they are used to confirm or deny the identity of other plants passing under the same name. Identification is first based on details of appearance, but it’s become much deeper with genomic tools. This “gold standard” is a plant-by-plant status – our unknowns are even stripped of names that they may once have carried. (The reasons we retain and study our unknowns are addressed in the Research section.) If, for example, our verified ‘Andrew Muehlig’ peony doesn’t match another specimen, then the other one is a variant – or misidentified.
- Cultivars are maintained as clones – there can be hundreds to thousands of identical individuals – this is why it’s important to know which are ‘true to name’ and which are not part of the clone and for some reason have a wrong name.
- As a reference collection, we are open for visitors and specialists to compare, but we do not offer identification services (more about those issues in our Research section.)
Cultivar Verification – building to the ‘Gold Standard’
Definitive identification takes teamwork – it requires more than one person’s opinion. The first step is visual inspection by specialists who know what to look for. Multiple years of intense work sessions by an international board of advisors led this plant-by-plant review – always in discussion teams. Nearly all the herbaceous peony cultivars in the garden have had their identity confirmed to one of four levels:
- unquestioned identification,
- reasonable to assume identification (peonies can slightly vary place to place and year to year based on growing conditions),
- matches the original description but none of the evaluators have seen it before, and
- Misidentified – these are listed as ‘Unknown’.
The next step in ‘Gold Standard’ identification is to create molecular (genomic) profiles of the plants that allow individual-level resolution. Since many peony breeders introduced cultivars that were bred from related parent plants (or even back-crossed among generations), its important to know if the plant-in-hand might be what in people we’d call a sibling, half-sibling, cousin, or many other combinations that in English would be considered incest. These may “look” very similar, but genomic profiling can resolve them apart.
More about this is in our Research section!
It takes a team of gardens to aggregate genomic profiles and match that information back on the written historic records. Once several gardens have the same genomic profiles for the same cultivars, there is no doubt of that cultivar and how to identify it. This level of confirmation also allows us to understand local differences in how the flowers look year-to-year and place-to-place. The molecular confirmation provides the essential base-line accuracy.
The Peony Garden is the founding and accredited partner of the Peony network in the Plant Collections Network (PCN) of the American Public Garden Association. At present there are 10 sister gardens that are likely to become accredited partners in this network, and among the group there are nearly 1200 peony cultivars – a genomic and cultural treasury for plant lovers, breeders and researchers. For significance – since the early 1800’s nearly 5,000 peony cultivars have been named, so the 1200 is a significant percentage of peony diversity. It is important that there is redundancy among the gardens – so that if a cultivar is lost at one there may be a duplicate that can be cloned and shared. As of 2022, just under half of the cultivars at the Peony Garden are not known to be in other collections – truly a collection of now-rare plants at risk of extinction.
A conservation model based on new methods
In the coming seasons there will be more than one way to unquestionably verify a peony – a genomic fingerprint. In 2013 we began to collaborate with Dr. Nastassia Vlasava and her colleagues at the Central Botanical Gardens, Minsk, in the Republic of Belarus, to trial DNA-fingerprinting of visually-and-record verified peony cultivars at both institutions. This approach will remove all doubt, but it will take time and resources to work out the tools and then expand the numbers of cultivars in the studies. Both this Peony Garden and the Central Botanical Gardens, Minsk, maintain significant peony collections – in addition to many well-known peonies, the CBG Minsk’s garden is noteworthy for its wild species as well as including cultivars developed in the former Soviet Union that are virtually unknown in North America.
Our collaborative research is also focused on the ‘family tree’ of domesticated herbaceous peonies. In the long term we want to know how every cultivar fits – based on its genomics as that is the most reliable source of information. We already know that the historic records and some genomic data are not in agreement – it is unlikely the genomic data is incorrect. As we build this tool and data set, one of our hopes is to be able to identify the ‘Unknowns’. Their genomic profiles will allow us to relink them to their lost identities.
There’s so much potential here – as well as other studies – featured in our ‘Research’ section.
Our verified ‘Sylvia Saunders’ is thought to be extinct commercially and extremely rare world-wide. Changes in lifestyles of gardeners, horticultural fashions, and resultant market demand make some of these otherwise extinct historic peonies extremely valued today by gardeners, specialists, and commercial breeders.