Podcast Summary

New Books Network: Stephen A. Harris on "50 Plants That Changed the World"

Host: Dr. Miranda Melcher
Guest: Professor Stephen Harris
Date: September 17, 2025
Publisher: Bodleian Library

Episode Overview

This episode features Dr. Miranda Melcher interviewing Professor Stephen Harris about his new book, "50 Plants That Changed the World." The conversation delves into how Harris selected the titular fifty plants, the stories and histories behind them—ranging from globally significant crops to lesser-known species—and how their roles have evolved over time. The discussion covers methods for tracing plant origins, the cultural and industrial impact of specific plants, and the sometimes surprising histories and uses that bridge both the everyday and the extraordinary.

Key Discussion Points & Insights

1. Genesis of the Book and Selecting "The 50"

• Background: The idea for the book was suggested by the Bodleian editors, building on Harris’s expertise as the Druce Curator of Oxford University Herbaria ([02:25]).
• Selection Process:
  • Out of 35,000 plants exploited by humans, Harris whittled down his list with several criteria: personal experience, public familiarity, geographic and thematic diversity, the ability to tell good stories, and peer input ([04:07]).
  • Notable method: Peer review—asking about 10 colleagues for their own lists, resulting in more than half overlap ([06:17]).
• Quote:

  “Getting from 35,000 down to 50 is quite a challenge... I ended up with a list of about 300 in terms of a short list. And then I paired this down...which plants represent different ideas, they represent different parts of the world, they represent different times...[and] plants that have really good stories.”
  —Stephen Harris [04:07]

2. Research and Writing Challenges

• Easy Choices: Staples like wheat, barley, potatoes, and chilies.
• Harder Choices:
  • Some plants were difficult to make publicly engaging, e.g., thale crest—a model organism in plant science ([06:53]).
• Storytelling Focus: Keeping narratives fresh, even for familiar or obscure plants.

3. Tracing Plant Origins—A Multidisciplinary Approach

• Detective Work:
  • Uses morphology, archaeological finds, DNA analysis, and etymology to piece together plant origins ([08:44]).
  • Example: Wheat’s origins involve at least three near eastern species. The domestication of broad beans is still mysterious—possibly due to extinction of wild relatives.
• Quote:

  “It's not simply the case of finding, if you like, a species in the wild and then bringing it into domestication ... A lot of this happened when people didn't really know precisely what was going on.”
  —Stephen Harris [08:44]

4. Plants in Religion and Symbolism

• Religious Integration:
  • Many world religions incorporate plants, e.g., wheat and grapes (Christianity), mirroring plants’ centrality in daily life ([12:53]).
• Legacy Adaptation:
  • Rogation period in Christianity is derived from Roman Robigalia, emphasizing the continuity and adaptation of rituals ([14:05]).

5. Plant Folklore: Mandrake and Beyond

• Mandrake:
  • Deep roots (pun intended) in ancient folklore—referenced in Sumerian, Egyptian texts.
  • Its human-shaped root and psychoactive properties have generated enduring magical associations ([15:50]).
• Quote:

  “One of the reasons that mandrakes are...so strongly associated with...folklore is obviously the form. So they have these roots which...can take on the human form. And they look like they look like humans.”
  —Stephen Harris [15:50]

6. Overlooked but Important: Sugar Beet & Industrial Crops

• Napoleonic Industry:
  • Sugar beet’s rise during the Napoleonic wars was driven by blockades and necessity, becoming France's alternative to sugarcane ([18:54]).
  • Artificial selection improved crop yield, and its use expanded beyond sugar to animal fodder.
• Quote:

  “There was this great push by Napoleon to take on this northern European crop and to force essentially French farmers to grow sugar beet for sugar production, for industrial sugar production.”
  —Stephen Harris [18:54]

7. Rise and Fall: Shifting Plant Importance

• Woad, Indigo, and Rubber:
  • Woad (blue dye) was vital in 15–16th century Europe but faded after the discovery of indigo and, later, synthetic dyes.
  • Rubber: From oddity to industrial necessity with the advent of vulcanization and the automobile ([25:41]).
  • Soya: Ancient in China, but recently industrialized in the West for oil, plastics, and protein.
• Quote:

  “There are certain plants...in the 14, 1500s in Europe [that] were really, really important. Woad...people really had to make that decision between growing food plants or growing this industrial, this industrial blue dye....but over time...these natural dyes like woad, indigo...then artificial pigments...”
  —Stephen Harris [25:41]

8. Cultural, Political & Agricultural Stories: The Sunflower

• Symbolism and Science:
  • Originally North American, sunflower became agriculturally vital first in Russia/Ukraine, then returned to North America after extensive breeding ([31:28]).
  • Its oil was acceptable during Orthodox Lent, increasing its popularity.
• Quote:

  “Russian scientists and Ukrainian scientists got involved in breeding these and they bred these sunflowers. They dramatically increased the size of the seeds and also the quality of the oils that were produced. And it's these seeds which were then in the 1950s, were then moved back into North America and become the foundation of the North American sunflower industry.”
  —Stephen Harris [33:46]

9. Obscure Yet Impactful: Lycopods and Thale Crest

• Lycopods:
  • Ancient plants, main ingredient of coal; their burning shaped industrial civilization and climate change awareness ([35:16]).
  • Modern uses: flash powder, early photography, lubricants.
• Thale Crest (Arabidopsis):
  • Chosen for its importance to plant biology as a model organism—the most genetically and biochemically studied plant ([35:16]).

10. The Value of "Weeds": Ragwort

• Why Include a Weed?
  • Symbolizes invasive and problematic species, highlights ongoing environmental challenges, and reflects the author’s own research interests ([40:06]).
  • Harmful to livestock; its management is significant in agricultural economics.
• Quote:

  “The reason for including ragwort is because it is representative of...weed and invasive plants, plants that we...move around, we change habitats so that plants move into, they compete with our activities. They have become really important. They are one of the big environmental things, threats that are faced by natural communities.”
  —Stephen Harris [40:06]

11. Banana Mythbusting

• Do Bananas Grow on Trees?
  • No; bananas are giant herbs, not trees. What appears as a trunk is actually leaf bases.
• Quote:

  “What you need to think about in terms of the thing that you look at as a banana plant is to realize that the stem of the plant is actually ground level or underground. And what you're seeing that are sticking up are in fact the leaves....bananas do not grow on trees.”
  —Stephen Harris [43:13]

12. Current & Future Work

• Harris’s upcoming book will focus on herbarium collections and their crucial role in the history of botany and understanding plant diversity changes ([45:36]).

Notable Quotes & Memorable Moments

• On Plant Origins:
  “Nature was doing their stuff. You were getting crossing going on between species. You're getting hybridization. People were seeing things that they liked...(and thought) ‘I'll bring that into my garden.’”
  —Stephen Harris [10:00]

• On Mandrake's Folklore:
  “As humans, we're extremely good at seeing patterns within, within nature. And you can see a human form [in the mandrake]...that would give it perhaps a particular significance.”
  —Stephen Harris [15:50]

• On the Industrial Potato:
  “Potatoes, chilies—these sorts of things—came easily [to the list]. The more difficult ones were actually trying to write about them in a way that would engage people...”
  —Stephen Harris [06:53]

Important Timestamps

| Timestamp | Segment | |-----------|--------------------------------------------------| | 01:34 | Introduction & premise of the book | | 02:25 | Stephen Harris’s background | | 04:07 | Criteria and process for plant selection | | 08:44 | Methods for tracing plant origins | | 12:53 | Plants in religious and symbolic contexts | | 15:50 | Mandrake’s legendary status | | 18:54 | Sugar beet, Napoleonic era, artificial selection | | 25:41 | Rise & fall of plant importance: woad & rubber | | 31:28 | Sunflower’s cultural/economic journey | | 35:16 | Lycopods, coal, and thale crest | | 40:06 | The significance of ragwort and weeds | | 43:13 | Bananas: tree or herb? Mythbusting | | 45:36 | Future projects: herbarium collections |

Conclusion

Professor Stephen Harris’s "50 Plants That Changed the World" masterfully intertwines science, history, and storytelling. Through this interview, listeners are invited to look more closely at the quiet powers of the plant world—how plants have not only shaped diets and economies, but rituals, industries, and even myths. Whether discussing the journey of the sunflower from the Americas to Ukraine, or busting the myth of banana trees, Harris’s passion for botany and history is palpable. The episode stands as a compelling reminder of how our societies are deeply rooted—often quite literally—in the green world around us.