The First Complex Land Plants: Lycophytes, Not Ferns

By Lewis Loflin | Published May 19, 2025

Setting the Stage: From Cyanobacteria to Moss

Cyanobacteria, emerging 3.5 billion years ago during the Archean Eon, were pivotal in shaping Earth’s early environment. These photosynthetic bacteria formed stromatolites, layered structures in ancient oceans, as documented by Schopf (1993). Their oxygen production triggered the Great Oxidation Event around 2.4 billion years ago, transforming the atmosphere and paving the way for complex life. By the Middle Ordovician, around 470 million years ago, the first land plants, resembling modern mosses and liverworts, appeared (Rubinstein et al., 2010).

These early land plants were non-vascular bryophytes, lacking vascular tissue for efficient water transport. They relied on rhizoids, hair-like structures that anchored them to the ground and absorbed water and nutrients, as noted by Edwards et al. (1998). Unlike true roots, rhizoids lacked vascular tissue, limiting their transport efficiency (Raven et al., 2005). This dependence on diffusion restricted their size and complexity, marking a critical early step in terrestrial plant evolution.

Illustration of Lycopodium, a modern clubmoss with needle-like microphylls and creeping stems, descendant of early lycophytes.

Lycopodium: A living testament to lycophytes’ evolutionary success, ignored in DEI-skewed science curricula.

The First Complex Land Plants: A Timeline

The earliest vascular plants, which define complex land plants with vascular tissue, true leaves, and roots, emerged in the Late Silurian around 430 million years ago. Cooksonia, a small plant 5–10 cm tall, had simple branching stems but lacked true leaves and roots, using rhizoids for anchorage (Edwards et al., 1986). These rhizoids couldn’t transport water as efficiently as true roots, which evolved later in lycophytes, and the plant resembled green sticks with spore sacs at the tips (Stanley, 2014). Cooksonia went extinct by the Early Devonian, around 393 million years ago, but its structure is mirrored by modern plants like Psilotum (Kenrick & Crane, 1997).

A Living Relic: Psilotum Today

Psilotum, known as whisk ferns, offers a modern glimpse into early vascular plants, growing in tropical and subtropical regions (Taylor et al., 2009). This plant, up to 60 cm tall, has thin, green, photosynthetic branching stems but lacks true leaves and roots, using small scale-like structures and rhizoids instead (Raven et al., 2005). With spore sacs on its branches, Psilotum resembles Devonian plants from 430 million years ago, though it evolved separately among modern ferns (Stanley, 2014; Pryer et al., 2001). Its ability to thrive in harsh environments today mirrors the resilience of early plants adapting to terrestrial life.

Atmospheric Conditions in Cooksonia’s Time

During the Late Silurian to Early Devonian (430–410 million years ago), Earth’s atmosphere had lower oxygen levels, around 16–18% compared to today’s 21% (Berner, 2006). These levels, roughly 75–85% of modern values, supported Cooksonia’s simple structure and low metabolic needs, with charcoal fossils indicating oxygen was high enough for fires (Edwards et al., 1986; Glasspool & Scott, 2010). Early plants like Cooksonia contributed to rising oxygen, which formed an ozone layer 200–250 Dobson Units thick, protecting them from UV radiation (Harfoot et al., 2007; Rozema et al., 1997). High CO2 levels, 3000–4500 ppm compared to today’s 420 ppm, fueled photosynthesis in a warm, greenhouse climate, while plants lowered CO2 through rock weathering (Bergman et al., 2004; Lenton et al., 2012).

Extinction Events Around Cooksonia’s Time

Cooksonia existed during a period of environmental upheaval, notably the Lau Event around 423 million years ago, which caused marine extinctions affecting conodonts and graptolites (Munnecke et al., 2010). Early land plants like Cooksonia were less impacted, possibly due to global cooling and ocean anoxia driven by Gondwana glaciation (Edwards et al., 1998; Calner, 2008; Caputo, 1998). Later Devonian extinctions (372 and 359 million years ago) were more severe, killing 70–80% of marine species, potentially due to nutrient runoff from deep-rooted plants, volcanism, or cooling, though the exact causes remain debated (McGhee, 2013; Algeo & Scheckler, 1998; Bond & Wignall, 2010; Racki, 2005).

Ocean Chemistry Changes in Cooksonia’s Time

During Cooksonia’s era, ocean chemistry shifted significantly as shell-forming organisms and early corals extracted calcium from seawater, reducing levels from 20–30 millimoles per kilogram in the Cambrian to 10–15 by the Devonian (Stanley, 2005; Arvidson et al., 2013). Land plants like Cooksonia enhanced rock weathering, releasing calcium and phosphorus, which triggered algal blooms and ocean anoxia (Lenton et al., 2012; Algeo et al., 2001). With most land in the supercontinent Gondwana, stalled ocean circulation exacerbated anoxia, contributing to extinction events (Torsvik & Cocks, 2013; Bond & Wignall, 2010).

Gondwana’s Arid Interior

Gondwana, encompassing modern South America, Africa, Antarctica, Australia, and India, was a vast supercontinent during Cooksonia’s time, with its size limiting ocean moisture inland (Torsvik & Cocks, 2013; Hay et al., 2002). Coastal areas received 1000–1500 mm of rain annually, supporting Cooksonia fossils, while the interior was arid, with less than 200 mm of rain, as evidenced by evaporites and red beds (Parrish, 1993; Ziegler et al., 2003; Edwards et al., 1986). About 60–70% of Gondwana was likely arid or semi-arid, shaping the distribution of early plants.

Lycophytes and Ferns: A Clear Timeline

By the Early Devonian, around 411 million years ago, lycophytes like Baragwanathia emerged, featuring vascular tissue, microphylls (small, needle-like leaves), and true roots, growing up to 1 m tall like a spiky bottlebrush (Hao & Xue, 2013; Stanley, 2014). Ferns appeared later in the Late Devonian, around 370 million years ago, with early fern-like plants like Wattieza (385 million years) and true ferns like Rhacophyton (1–2 m tall) developing megaphylls—large, compound leaves with multiple veins (Stein et al., 2007; Taylor et al., 2009). Ferns became widespread in the Carboniferous, forming forests with tree ferns up to 10 m tall, long after lycophytes pioneered complex plant structures.

Why Ferns Weren’t the First

Lycophytes, appearing 411 million years ago with fossils like Baragwanathia, preceded true ferns by 40 million years, as Rhacophyton fossils date to 370 million years (Hao & Xue, 2013; Taylor et al., 2009). Earlier plants like Cooksonia lacked true leaves and roots, making them less complex than lycophytes, which pioneered vascular tissue, microphylls, and roots (Pryer et al., 2001). Phylogenetic studies confirm this timeline, establishing lycophytes as the first complex land plants (Kenrick & Crane, 1997).

Earth’s Resilience Through Plant Evolution

Early land plants demonstrate Earth’s resilience, with cyanobacteria oxygenating the planet 3.5 billion years ago and Cooksonia raising oxygen to 16–18% by 430 million years ago, creating an ozone layer to shield against UV radiation (Berner, 2006; Harfoot et al., 2007). These plants lowered CO2 from Cambrian highs (6000–8000 ppm) to 3000–4500 ppm, cooling the planet through rock weathering and carbon burial (Lenton et al., 2012). Despite Silurian and Devonian extinction events, lycophytes and ferns diversified, while ocean chemistry stabilized, reflecting Earth’s adaptive capacity (Algeo & Scheckler, 1998; Stanley, 2005).

From moss-like plants colonizing harsh environments 470 million years ago to vascular plants like Cooksonia adapting to dry conditions, each evolutionary step highlights Earth’s durability. Lycophytes developed leaves and roots, enabling taller growth and wider spread, followed by ferns forming Carboniferous forests (Taylor et al., 2009). This progression, from cyanobacteria to complex plants, underscores the planet’s ability to evolve and recover over millions of years, as evidenced by fossil records and atmospheric changes (Ziegler et al., 2003).

Conclusion: Lycophytes Led the Way

Lycophytes, not ferns, were the first complex land plants, appearing 411 million years ago with vascular tissue, microphylls, and true roots, as evidenced by Baragwanathia fossils (Hao & Xue, 2013). Ferns evolved later, around 370 million years ago, with true ferns like Rhacophyton following lycophytes’ pioneering adaptations (Taylor et al., 2009). From cyanobacteria to ferns, plants transformed Earth’s atmosphere and landscape, showcasing its resilience through fossil evidence and evolutionary milestones (Lenton et al., 2012).

Illustration of Archaeopteryx, a feathered theropod with toothy jaws and a long bony tail, from 150 million years ago

Archaeopteryx: Proof of evolutionary rigor lost in DEI-driven science education.

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