In Defense of Plants Podcast

Episode 560: Revisiting Earth's First Forests

Date: January 11, 2026
Host: Matt (In Defense of Plants)
Guest: Dr. Chris Berry, Cardiff University – Paleobotanist

Overview

This episode explores the origin and nature of Earth's first forests during the Devonian period—a transformative era for plant evolution. Host Matt revisits a 2020 conversation with Dr. Chris Berry, whose decades of paleobotanical research have shed light on these ancient ecosystems. They discuss the explosion of plant diversity, the mechanics of fossil formation, reconstructing ancient plant life, and the ongoing mysteries and detective work at the heart of paleobotany.

Key Discussion Points & Insights

Dr. Berry’s Path to Paleobotany

• Inspired by childhood fossil-collecting with his father and an early exposure to geology at school.
• The pivotal shift to paleontology at Cambridge University, where encountering experts (e.g., Simon Conway Morris) sparked his interest in ancient life.
• Initially more focused on animal paleontology, but a “chance encounter” led him to pursue a rare PhD project on Devonian plants with Diane Edwards at Cardiff.
• Quote:

  “I was very lucky that she was enthusiastic... so I came down to Cardiff and got stuck into Devonian plants and botany.” (04:29)

The Devonian: "Cambrian Explosion" for Plants

• The Devonian marked a dramatic evolutionary radiation, paralleling the Cambrian explosion in animals.
• Key innovations: increased size, complexity, wood, leaves, secondary growth, and the rise of seeds by the end of the period.
• Evolutionary "experiments" resulted in bizarre and novel plant anatomies, many unlike anything seen today.
• Quote:

  “You get this explosion of form and to some extent function in plants, which is quite extraordinary to follow through.” (06:54)

The Alien Nature of Early Forests

• Devonian forests were unlike modern forests—few (if any) animals, no large herbivores, and plant forms that defy modern analogies, making it difficult to reconstruct or compare their scale.
• Early reconstructions often struggled with scale due to the lack of animal fossils for context.
• Quote:

  “There’s nothing you can put in the picture that gives you a sense of how big it was.” (09:18)

• Notable mention of the millipede for scale on the famous Gilbert Forest Nature cover (10:25).

The Challenge of Fossilizing Forests

• Plant fossils are mostly fragmented; full reconstructions are rare and often based on composite specimens.
• Early paleobotany frequently pieced together unrelated plant parts, leading to inaccurate depictions.
• Major advancement: Dr. Berry’s work matching cladoxylopsid branches and trunks, revealing their palm-like structure.
• Milestones:
  • First full cladoxylopsid trees found in New York (South Mountain Quarry) and Germany (Lindlar Quarry).
  • Ongoing struggle to fully reconstruct other key Devonian plants, like Archaeopteris.

Mysteries of Ancient Tree Lineages

• Lycopsids: Have extant relatives (club mosses).
• Progymnosperms (e.g., Archaeopteris): Closer to modern seed plants but now extinct.
• Cladoxylopsids: Ancient, enigmatic; recent Chinese fossils show wood in multiple discrete strands, challenging their placement on the plant family tree.
• Current research focuses on anatomical evidence—do these forms have secondary phloem, and are they true lignophytes?
• Quote:

  “We don’t exactly at the moment know which branch of plant life they really belong to.” (18:20)

Devonian Geography and Global Plant Distributions

• Continents were not a single supercontinent but comprised of large and small landmasses; global climate was more uniform than today.
• Similar but not identical floras across regions, with evidence for biogeographical diversity and gradual mixing (e.g., Archaeopteris appears globally by late Devonian).
• Quote:

  “Each of these blocks has its own history of plants and we don’t know enough about enough of these fragments to really be confident that we understand how plants have changed on a global basis through the whole Devonian.” (21:38)

Fossil Forests: Rare Snapshots in Time

• True fossilized forests are extremely rare—only known from a handful of sites globally (New York, Spitsbergen, China).
• Importance: They preserve plant spacing, rooting systems, and local ecology—offering a “T₀” (moment-in-time) snapshot rather than a time-averaged assemblage.
• Tells us about soil, hydrology, and ecosystem structure.
• Quote:

  “To be able to walk on a surface and feel that you can sense where the plants were growing around you... is completely different.” (24:18)

Field Stories & Collaborations

• Dr. Berry’s adventures include following hand-drawn treasure maps to Arctic Spitsbergen and jet-lagged whirlwind trips to pivotal New York sites.
• Collaborative detective work, often driven by chance discoveries—quarries and road cuts play a key role, with large surfaces revealing fossil forests thanks to industrial activity.
• Memorable Moment:

  “To sit there on the quarry floor and just see where they were standing around you and imagine that vista of primeval forest was, yeah, just mind-blowing really.” (28:22)

Ancient Plant Structure & Ecology

• Not all trees grew upright—some, like those at Gilboa, had “tree-sized” rhizomes ambling along the ground, akin to modern club mosses.
• Soils were permanently wet; there may have been undergrowth, but poor preservation leaves mysteries about ecosystem complexity.
• Lack of co-evolved animals likely kept ecological interactions less complex than modern tropical forests.
• Quote:

  “You don’t have the coevolution with animals either. So... all these different species that evolved to live with various animals, that’s not going on in the Devonian.” (23:25)

Root Systems: The Stigmarian Mystery

• “Stigmarian roots” are distinctive to ancient lycopods; today’s Isoetes (quillworts) may harbor the relict form.
• These roots allowed extensive spread and survival in waterlogged soils—crucial for coal formation later.
• Oldest confident stigmarian roots described from late Devonian China; at some sites, enigmatic roots may be “20 million years too early.”
• Quote:

  “That stigma and root is a very significant thing. And in the last year’s report of this latest Devonian forest from China, these types of stigmarium rootlets were demonstrated.” (37:23)

The Never-ending Detective Work

• Paleobotany is ongoing detective work: making connections between disparate discoveries, often by “heightened perception” and deep familiarity with literature/collections.
• Most breakthroughs depend on luck, fieldwork, and collaboration across continents and disciplines.
• Quote:

  “It’s one of the great things, is just discovering stuff, just spending time seeing new things, breaking new rocks open, finding new localities.” (39:47)

What’s Next for Paleobotany?

• Dr. Berry is excited to conduct cell-level anatomical studies on silicified cladoxylopsids from China—these permit “Rhynie Chert”-level resolution in massive trees.
• There's still much to describe from previous discoveries—morphology and ecology—and an active interest in even older “mini-forests” predating the earliest full forests.
• Quote:

  “If anything... we’ve really moved forest down from being a late Devonian thing... it’s been exciting to work on the forest before the actual forest.” (47:10)

Notable Quotes

• Dr. Chris Berry (on the Devonian):

  “Why not? It’s got to be the best time to look at fossils.” (08:24)

• Dr. Chris Berry (on fossil discovery):

  “Nothing’s ever solved completely.” (39:25)

• Dr. Chris Berry (on the thrill of fossil forests):

  “To sit there on the quarry floor and just see where they were standing around you ... was just mind-blowing.” (28:22)

• Dr. Chris Berry (on future research):

  “Mini forests, I think, is my next hope.” (47:28)

Notable & Memorable Moments

• Dr. Berry’s account of jet-lagged, last-minute trip to see the Gilboa Forest, standing where he’d spent decades reconstructing from fragments. (28:22)
• Descriptions of ancient forest structures—some trees growing as giant horizontal rhizomes instead of upright trunks. (30:27)
• Discussion of industrial quarries inadvertently enabling major paleobotanical finds. (42:18 – 44:46)

Important Timestamps

• 01:56 – 06:42: Dr. Berry’s background and entree into Devonian paleobotany
• 06:42 – 10:12: The Devonian explosion of plant diversity—what made it unique
• 14:35 – 18:33: Milestones in reconstructing early forests, challenges in fossil interpretation
• 19:11 – 23:38: Devonian continental geography and its implications for plant distribution
• 24:14 – 32:59: Rare fossilized forests—significance, discovery stories, and what they teach us
• 35:52 – 39:22: Stigmarian roots and paleobotanical clues to ancient plant ecology
• 41:41 – 44:46: The role of modern industrial activity (quarries, road cuts) in paleobotanical discoveries
• 45:07 – 47:34: Dr. Berry’s current and future research directions

Closing & Further Resources

• How to Learn More:
  Dr. Berry recommends searching Google, following him on Twitter, checking Cardiff University pages, and exploring the work of his US colleagues (Bill Stein at Binghamton, New York State Museum).
• Host's Reminder:
  Full links and details are in the show notes at indefensibleplants.com.

Summary Takeaway

This episode brings to life Earth’s first forests—an alien world of giant, strange plants evolving in the absence of animals, their history reconstructed from rare fossil sites and decades of dedicated detective work. The Devonian’s lessons are still unfolding, with every new fossil potentially rewriting what we know about the rise of life on land.