January 4, 2021 Invasive Garlic Mustard, Stephen Hales, Johanna Weterdijk, Eleanor Perenyi, Winter Garden Thoughts, A Life in Shadow by Stephen Bell, and Garden Trivia for National Trivia Day

Show Notes

Today we celebrate an English botanist who discovered which way sap flows in plants.

We'll also learn about a female Dutch botanist who fought for equity and is now remembered as a trailblazer.

We’ll remember a thoughtful and witty garden writer whose only book became a garden classic.

We hear some thoughts on the garden in winter from one of my favorite authors.

We Grow That Garden Library™ with a book that shares the story of the French naturalist and medical doctor Aimé Bonpland (“bon-plon”).

And then we’ll wrap things up with a little garden trivia in honor of National Trivia Day.



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Invasive Species Spotlight: Garlic Mustard | Washington Gardener | Jacqueline Hyman


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Important Events

January 4, 1761
Today is the anniversary of the death of the English clergyman, botanist, and physiologist Stephen Hales.

Stephen applied himself to many different areas of science. Stephen spent most of his life studying tree sap and blood flow.

Do you know the direction sap flows in a plant? Stephen figured this out - it flows upward - and he also examined other fascinating aspects of plants like the sap's pressure, the pressure roots exert on sap, and how fast shoots and leaves grow. He also demonstrated that plants absorb air.

Stephen’s curiosity about sap and blood flow led him to become the first person to measure blood flow, blood volume, and blood pressure.

Stephen was always thinking about the forces around us - from our internal blood pressure to external air pressure. It’s not surprising that Stephen became curious about air quality and whether improved airflow could help fight typhus. And so, Stephen invented a ventilator to purify stale air. Stephen’s device was essentially large bellows that had to be moved by hand, but they were still effective and were used in ships, prisons, and mines. And there was another use for Stephen’s ventilator: it also preserved and dried food.

In the twilight of his life, Stephen had royal visitors. Frederick, Prince of Wales, and his wife, Princess Augusta, both stopped by to discuss gardening and botany. And it was Stephen Hales who gave Princess Augusta advice on the creation of Kew Gardens.

Today, Stephen is remembered in the genus for the snowdrop tree, the Halesia carolina.

And since 1927, the Stephen Hales Prize is awarded to a scientist who made an outstanding contribution to plant biology science.


January 4, 1883
Today is the birthday of a Dutch plant pathologist and the first female professor in the Netherlands, Johanna Westerdijk, who went by "Hans."

In 1906, Johanna completed her thesis on the regeneration of mosses, and she was hired to be the director of a major botanical institute at the ripe old age of 23. By 1917, Johanna became the first female professor in the Netherlands. During her tenure, Johanna supervised 56 doctoral students - half of them women - and she strongly believed in equal opportunities for women. She once said,

“I strive for a genuinely equal division of men and women in high positions.”

To illustrate how her peers perceived Johanna during her lifetime, check out this excerpt from The Lincoln Star Journal from October 29, 1914. Johanna had traveled to America to visit the Missouri Botanical Garden, and the article was titled, “Woman Botanist Who Smokes and Drinks Publicly.”

“A famous woman botanist, who both drinks and smokes In public, is now in the United States. Doctor [Charles] Bessey of the State University met her in St. Louis a short time ago. The name of the peculiar woman is Doctor Johanna Westerdtjk, and she is in charge of the pathological laboratories in Amsterdam.

"She was quite enraged because botanists did not pay quite as much attention to her in St. Louis as she thought she deserved," said Doctor Bessey.

"She insists that women should have the same rights as men and is in rebellion against American conventions. In large hotels, wherever it is permissible, she stays up late and drinks and smokes In the lobby."

Doctor Bessey has a picture of all the botanists in attendance at the Missouri Botanical Gardens' anniversary.

There is Miss Johanna Westerdijk, cigarette in hand. She appears to be the only one of any of the men or women in the picture who is smoking. Doctor Bessey believes that there is little danger of the learned doctor coming as far as Lincoln on her American travels.”

Joanna led an all-female team of scientists who identified the fungus that caused Dutch Elm disease. Joanna’s Dutch Elm Committee was a group she formed on her own to fund additional research for elm disease.

Johanna was a pioneer in plant pathology and fungi, and her system is still used to classify species.

Today Johanna is remembered for some great quotes:

“Both work and play are needed to create a beautiful mind.”


"Even fungus dies from a dull and monotonous life." 

Today, at the university, there’s a wall showing the photos of all the professors of her time - all men, of course - and right there, in the lower bottom left frame, is a painting of Johanna.

And almost four years ago, on February 12, 2017, the Fungal Biodiversity Centre Institute was renamed the Westerdijk Institute in honor of Joanna. She served as the Institute’s Director for over fifty years. Today, the Westerdijk Institue is the largest microbial, fungal resource center in the world.


January 4, 1918
Today is the birthday of the American writer and gardener Eleanor Perenyi.

We lost Eleanor in 2009, at the age of 91.

Her book, Green Thoughts, is widely considered to be a classic of garden writing. Sadly, it was Eleanor's only book.

Eleanor wrote about working in her Connecticut garden, and she was not a fan of rock gardens, chemical pesticides, or petunias.

She once called petunias,

“as hopelessly impractical as a chiffon ball dress.”

And her book Green Thoughts gives us many more witty quotes and sayings from Eleanor. Here are a few of my favorites:

“A little studied negligence is becoming to a garden.”

“The double hoops for peonies are beyond-description maddening to unfold and set in place.
Two people are needed, one of them with better control of his temper than I have.”

“I ordered a modern purple martin house myself
and proceeded to construct a dreadful object:
unpainted, it looked like a cheap motel;
painted blue and white, it looked like a cheap Greek motel
and had to be thrown out.”

“A killing frost devastates the heart as well as the garden.”

And finally, here's a quote for gardeners who are too hard on themselves. Eleanor recognized that this happens - quite a bit.

“It takes a while to grasp that not all failures are self-imposed -
the result of ignorance, carelessness, or inexperience.
It takes a while to grasp that a garden
isn't a testing ground for character
and to stop asking,
“What did I do wrong?”
Maybe nothing.”


Unearthed Words

I have had to enjoy the winter garden vicariously, with the help of books. The best for this purpose I’ve found is Elizabeth Lawrence’s new one. Gardens in Winter (Harper), which has allowed me to share the delights of the author’s garden in Charlotte, North Carolina, as well as the gardens and woods she knows from her wide reading.

Miss Lawrence is a classicist and can cite Virgil and the English poets as freely as she does Gertrude Jekyll and Jane Loudon. In this volume, she leads us most often to the English garden of Canon Henry Ellacombe, from whose two books In a Gloucestershire Garden (1896) and In My Vicarage Garden (1902) she often quotes.

She also takes us to Walden Pond and Concord, in the winter sections of Thoreau’s Journal. In North Carolina, Miss Lawrence says, there are two springs—the first in autumn, just after the killing frosts, and then the true spring, which starts on St. Valentine’s Day—but she reminds us that it was Thoreau who wrote, “All the year is a spring,” and her book seems to prove this to be true, even in the North.

She has collected winter-garden notes and-flowering dates from her network of correspondents all over the United States and shares these with her readers. Though we Northerners will envy her her iris and camellias in November, her roses and hardy cyclamens in December, and her violets and hoopskirt daffodils in January, she shows us that all winter, even in the most frigid and unlikely spots, there are flowers or shrubs in bloom or, at the very least, in fruit, if we look for them carefully.
— Katharine S. White, gardener and garden writer, Onward and Upward in the Garden,


Grow That Garden Library

A Life in Shadow by Stephen Bell

This book came out in 2010, and the subtitle is Aimé Bonpland in Southern South America, 1817–1858.

In this book, Stephen shares the story of the French naturalist and medical doctor Aimé Bonpland, one of the most important South American scientific explorers in the early nineteenth century.

Working alongside Alexander von Humboldt, Aimé later conducted his own research and went much farther south than Humboldt. Stephen outlines Aimé’s movements through Argentina, Paraguay (where he was imprisoned for nearly a decade), Uruguay, and south Brazil. By exploring the interior of South America, Aimé’s experience is a unique account of the natural world - along with the social and economic circumstances of the era.

Stephen’s well-researched book is no longer in print, but you can still find rare copies online.

This book is 336 pages of fascinating history, showing Aimé Bonpland’s life in rich detail.

You can get a used copy of A Life in Shadow by Stephen Bell and support the show using the Amazon Link in today's Show Notes for around $62


Today’s Botanic Spark

Reviving the little botanic spark in your heart

Today is National Trivia Day, and in honor of that, I thought I’d close today’s show with some Garden Trivia with you.



  1. Are Almonds in the rose family?
  2. What is the world’s tallest tree?
  3. In the 1600s, what flower had the most value?
  4. Where was the Poinsettia discovered?
  5. What is the largest flower in the world?



  1. Yes - along with apples, peaches, pears, cherries, raspberries, strawberries, and more  
  2. The coast redwood (Sequoia sempervirens)
  3. The Tulip. In the 1600s in Holland, tulips were worth more than gold and caused the crash of the Dutch economy.  The craze was called tulip mania or tulipomania.  
  4. Mexico. In 1825, the first U.S. minister to Mexico, Joel Poinsett, introduced the plant to America.
  5. The titan arum (Amorphophallus titanium)


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