Podcast Summary:

Podcast: New Books Network
Episode: Stephen D. Hopper, "Eucalyptus" (Reaktion, 2025)
Date: November 23, 2025
Host: Dr. Miranda Melcher
Guest: Professor Stephen Hopper

Overview

In this episode, Dr. Miranda Melcher interviews Professor Stephen Hopper about his new book, Eucalyptus (Reaktion, 2025). The discussion explores the ecological, cultural, and historical significance of eucalyptus trees, with a focus on their centrality in Australian and Aboriginal life, their scientific diversity and adaptability, current conservation challenges, and ongoing research. Hopper’s unique perspective bridges Western botanical science and centuries-old Aboriginal knowledge, aiming to foster broader understanding and more effective conservation strategies.

Key Discussion Points & Insights

1. Background and Motivation for the Book

• Hopper introduces himself as a conservation biologist with 50 years of experience, former director of both Kings Park (Perth) and Royal Botanic Gardens, Kew (London).

• He began focusing on eucalypt conservation in the early 1980s and collaborated with Dr. Ian Brooker to describe ~100 new species/subspecies (about a ninth of the currently recognized genus).

• The book is distinguished by its prioritization of Aboriginal knowledge systems and integration with Western scientific advances.

• Hopper has collaborated with Aboriginal elders for over 20 years, emphasizing traditional ecological knowledge in managing biodiversity.

  "It is the first attempt to give priority to Aboriginal knowledge systems on eucalypts, and that required a narrative style presentation because it's an oral tradition."
  — Professor Stephen Hopper [05:24]

2. Aboriginal Cultural Significance of Eucalyptus

• Eucalypts are referred to as "the universal Australians," omnipresent across the continent and central to Aboriginal culture.

• Aboriginal peoples developed a multitude of uses for eucalypts—medicine, tools, marker trees, water storage, and more.

• Culturally modified trees and Dreamtime stories are crucial, such as trees shaped to commemorate places, totems, or store water, and narratives linking trees to landscape formation and cultural norms.

  "Many Aboriginal cultures would modify the eucalypt horticulturally, manipulate them to produce marker trees in the landscape to signify important cultural places, important people, to store water in dry habitats and to celebrate totems."
  — Professor Stephen Hopper [08:29]

3. Stories and Examples from Aboriginal Traditions

• Hopper recounts specific Dreamtime stories and landscape features from southwest Australia, like the Magic Circle on Warrumbup Hill, where karri trees and granite boulders intertwine, believed by the Knapp family to be where trees gave birth to rocks.

• An example also discussed are twin-trunked karri trees, culturally modified to symbolize elements of spiritual narratives (such as the spirit woman and the Milky Way).

  "This is the place known for where the trees gave birth to the rocks...it does indeed look like that with this callus-like tissue beginning to surround the rocks adjacent to the trees themselves."
  — Professor Stephen Hopper [11:00-12:00]

  "She was trampolined up into the night sky and her long silver hair became the Milky Way...the twin trunks are her legs and a short body..."
  — Professor Stephen Hopper [14:00-15:00]

4. Etymology and Classification of “Eucalyptus”

• The name “Eucalyptus” was coined by French botanist Charles Louis L'Héritier from English collections at Kew Gardens during the Enlightenment period.

• The term means “well covered,” referencing the distinctive cap over the flower bud.

  "He named Eucalyptus...the name he chose means well-covered, and it alludes to a cap that sits over the bud and it's a fusion of petals and sepals..."
  — Professor Stephen Hopper [21:10]

5. Evolution and Biogeography

• Traditional theory held eucalypts originated on rainforest margins—recent theory (Hopper 2021) suggests their roots are in ancient, dry, infertile Australian landscapes where sclerophyll (hard, drought-tolerant leaves) evolved.

• Fossils support both hypotheses, but more testing is needed to resolve the debate.

  "There are now these two creation hypotheses for eucalypts...the evidence is yet to come in to convince most people."
  — Professor Stephen Hopper [25:40]

6. Species Diversity and Identification

• About 900 species are known, with 850 formally described and more likely to be found.

• DNA sequencing is revolutionizing Eucalyptus classification, confirming or reclassifying species, subspecies, and hybrids.

• Eucalyptus as currently classified comprises four major genera:

  • Eucalyptus (~750 species),
  • Angophora,
  • Corymbia,
  • Blakehella (recently separated from Corymbia in 2024).

• Identification can range from easy (distinct species) to highly challenging (closely related radiations).

  "Many of them are in groups of very close relatives, and you require many techniques to really be sure that you're looking at different species or subspecies these days."
  — Professor Stephen Hopper [27:44-28:00]

7. Ecology, Adaptability, and Global Spread

• Eucalypts thrive in nearly every Australian habitat except the driest deserts and have been introduced globally due to their quick germination, rapid growth, utility for timber/firewood, and disturbance resilience.

• Certain species have become essential in environmental management, like draining swamps in Italy.

  "They are incredibly fast growing...They provide firewood, of course, they're hardwood species and they've been planted worldwide for that reason...They can be used in environmental manipulation and repair."
  — Professor Stephen Hopper [35:55-36:45]

8. Conservation Status and Threats

• Threats include agricultural clearing, urban infrastructure, and potentially climate change.

• Classification of threat has shifted from mere rarity to range reduction and generational turnover.

• Remarkably, no Eucalyptus species are known to have gone extinct since European scientific records began, though about a quarter are now considered threatened, especially under expanded criteria.

  "We have this anomaly, you know, with the eucalypts are incredibly resilient, as I've mentioned, they're capable from bouncing back from destructive events, but if a quarter of them are threatened, then in the longer term we really do have to help some of them survive."
  — Professor Stephen Hopper [42:44]

  "Climate change is the biggest threat that we're all increasingly becoming aware of...for the first time...common trees like Mary trees started to die or at least lose their canopies."
  — Professor Stephen Hopper [43:56-44:38]

9. Ongoing and Future Work

• Hopper continues to publish on specific eucalypt taxa and on kangaroo paws (his doctoral focus).

• He works closely with Aboriginal elders to integrate indigenous and scientific approaches to land stewardship and plant conservation.

• Upcoming projects include books presenting male and female Aboriginal perspectives on “caring for country,” a volume expanding his “old landscape theory,” and research on granite outcrop habitats.

  "The main thrust of what I'm doing now is to continue to work with Aboriginal elders on caring for country. They really are highlighting approaches that Western science needs to take serious consideration of in Australia..."
  — Professor Stephen Hopper [46:49]

Notable Quotes

• On integrating Aboriginal knowledge:
  "It is the first attempt to give priority to Aboriginal knowledge systems on eucalypts, and that required a narrative style presentation because it's an oral tradition."
  — Professor Stephen Hopper [05:24]

• On cultural landscape and Dreamtime stories:
  "This is the place known for where the trees gave birth to the rocks...it does indeed look like that with this callus-like tissue beginning to surround the rocks adjacent to the trees themselves."
  — Professor Stephen Hopper [11:00-12:00]

• On evolution and research uncertainty:
  "There are now these two creation hypotheses for eucalypts...the evidence is yet to come in to convince most people."
  — Professor Stephen Hopper [25:40]

• On resilience and threat:
  "Not a single known eucalypt has gone extinct. And that's quite unusual for plants in general. Often 10%, even more of species that have been described have gone extinct since Linnaean times."
  — Professor Stephen Hopper [42:12]

Key Timestamps for Segments

• [02:28]—Professor Hopper’s background, career, and inspiration
• [05:24]—Prioritizing Aboriginal knowledge and intended book audience
• [07:19]—Eucalyptus in Aboriginal culture and belief
• [09:42]—Dreamtime stories and specific cultural examples
• [18:53]—Scientific naming and etymology of "Eucalyptus"
• [22:52]—Evolutionary origins and competing hypotheses
• [27:08]—Species diversity, taxonomy, and identification challenges
• [33:52]—Habitats, ecological range, and global success
• [38:39]—Conservation threats and resilience
• [46:07]—Ongoing/future research and projects

Closing

The episode offers a vivid blend of science, history, and culture, revealing why eucalyptus trees are not just botanical icons but also enduring symbols in ecology, art, and indigenous heritage. Professor Hopper’s Eucalyptus provides an accessible, authoritative guide to their story—one that continues to unfold amid environmental change and cross-cultural collaboration.