Written by davethetreecenters • July 06 William Penn Barberry – A Beautiful Little-known Shrub

Sometimes the stories of our garden plants are as interesting as the plants themselves and knowing them adds to the pleasure of growing them. Just like getting to know your neighbors enriches your sense of community, learning more about your plants enriches your garden experience. It could be where on the planet they come from, who collected them, the history of their uses, the life of their creator, or some special botanical features. Some plants have very little to tell, while others hold our interested for hours. It also helps if they are attractive and versatile in the garden.

We recently acquire some plants of the William Penn Barberry , and a little research revealed a fascinating story that contains just about all the possible details and curiosities that any plant can have. We will hardly even mention William Penn himself, the British Admiral and Quaker leader who began the colony of Pennsylvania in 1682. (The inhabitants at the time were of course never consulted when the King of England ‘gave’ Penn 45,000 square miles of the future America).

The William Penn Barberry

But first, the plant itself. Almost every barberry seen in gardens is a form of the Japanese barberry, Berberis thunbergii. That plant is available in a host of sizes, shapes and leaf colors, and it’s an invaluable garden plant. If you live in areas where it has become invasive, there are today plenty of non-seeding forms that allow you to keep growing this tough, durable shrub. The William Penn Barberry, however, is not a kind of Japanese barberry at all. It is an evergreen shrub, probably only hardy to zone 6. It grows into an arching bush, perhaps 5 feet tall and wide, with spiny leaves and big stem-spines too. You might not want to roll around in it, but it makes a great screen, and it is a very attractive plant. The glossy leaves are rich green, and they turn deep red in fall, staying that way all through winter. In late spring, after the new green leaves have developed, large bright yellow flowers hang along the branches, in clusters of up to 10 blooms. It is a lovely sight. These become bunches of blue-black berries by fall, which will be enjoyed by your local birds. There is no evidence that this species can spread or become invasive, so you can grow it anywhere. We recommend it highly for something different and striking, as well as a plant that is easy to grow in both sun and partial shade, in any well-drained soil.

Ernest Henry Wilson, Plant Collector Extraordinaire

There are about 200 other barberries that grow around the world, but that are rarely seen in gardens. One parent of the William Penn Barberry is Berberis verruculosa, a plant from China sometimes called the warty barberry, because of the numerous brown bumps scattered across the bark. This evergreen shrub grows in western China, in Sichuan and Yunnan provinces, and it was found and introduced to western gardens by the famous plant explorer E.H. Wilson. Often called ‘Chinese Wilson’, this adventurous Englishman began his career collecting new plants for the famous Veitch’s Nursery. Charles Sprague Sargent, head of the Arnold Arboretum in Massachusetts at the time, took to the young man, and sent him to China. In 1903 he found and brought back Lilium regale, a garden lily that is a perennial border ‘standard’ still today. It was probably on that same expedition that he discovered the warty barberry. Unlike many other of Wilson’s introductions, the warty barberry never became popular or widely grown (the unfortunate name probably didn’t help!).

Mary Gibson Henry, An American Plant Enthusiast and Collector

A plant of the warty barberry did however end up in the garden of an American. Not just any American, but the large garden of Mary Gibson Henry, in Gladwyne, Pennsylvania. Born in 1884, Mary came from a wealthy family with gardening interests, and her grandfather had been a founding member of the Pennsylvania Horticultural Society. On her 50-acre garden she decided to grow the rare and unusual, and she went on over 200 collecting trips during her lifetime, all across America, seeking rare and unique plants she could grow. She died in 1967 while on what became her last collecting trip. In 1950 she had protected her legacy by turning her garden into an endowed trust, still existing today, called the Henry Foundation for Botanical Research.

A Chance Seedling is Found

Around the middle of last century Mary was out in the garden, and she spotted an unusual seedling growing beneath her plant of the warty barberry. She dug it up and grew it for a few years. She concluded after close examination that this new plant was a hybrid between Berberis verruculosa and another Chinese barberry called Berberis julianae. That striking evergreen is certainly a plant that should be seen in gardens much more often. It also fits into our story nicely, because it was an earlier introduction by E. H. Wilson, from 1900, when he was still working for Messrs Veitch, as the English usually refer to that nursery. Mary Henry named her plant ‘William Penn’, and in 1963 she patented it. We can see the exponential growth of plant patents in the fact that she was only number 2, 212, although the first plant patent in America had been granted 32 years earlier. That #1 was for the climbing rose ‘New Dawn’, a beautiful plant which is still work growing. Today there are over 31,000 patents, although of course many, like Mary Henry’s ‘William Penn’ have expired. Plant patents are only valuable for 20 years.

What Exactly is the William Penn Barberry?

This is where the botanists step into the picture. Always looking to revise and improve accuracy, today botanists don’t think Mary Henry was right about the parentage of her plant. Instead they think that the pollen donor to her warty barberry was Berberis gagnepainii, yet another of Wilson’s introductions. It is clear that Ernest was a man who clearly loved barberry plants! Wilson probably brought it back from Sichuan along with the warty barberry, and although not known much in America, that plant does have a European ‘following’. In fact, hybrids between the same two species – B. verruculosa and B. gagnepainii – were created in Holland and France last century, before Mary Henry’s seedling appeared. First was ‘Terra Nova’, found in the Netherlands in the 1920s. 1933 saw the appearance of ‘Chenaultii’, from the Chenault Nursery in Orleans, France. ‘Wallich’s Purple’ is yet another, from the Netherland’s in the 1960s. Mary Henry’s plant was perhaps not as unique as she thought, but it is probably the ‘pick of the litter’ for garden worthiness. As for the correct name, Berberis x gladwynensis is our favorite, as it honors Mary’s garden appropriately. The Europeans are more likely to call it Berberis × hybrido-gagnepainii. Wow, those botanists love to dazzle us with complicated names!


So the story of the William Penn Barberry turns out to be quite a tale. If you do choose to grow them in your garden – and we recommend you do – then you have a good yarn to tell when showing it off to family, friends, and neighbors!

***If you want to check the availability of any of the plants mentioned here, go to our Home Page, click on the ‘Search’ button in the upper right, and type in your choice – both common names and botanical ones will work. If, sadly, you find the item sold out, click on the ‘notify me’ box beside the size you want, and you will get an email the moment that plant is available again – it’s easy.