The Ancient Ferns With Stomata So Large They Defy Botanical Expectations

Gardening · Published 3 October 2026 Swipe more like this →

In short: Marattiaceae are evolutionary outliers, diverging from other ferns over 300 million years ago. These living fossils feature massive, fleshy rootstocks and the largest fronds in the fern world. Some species even possess the largest stomata in the entire plant kingdom, marking them as a truly distinct lineage of life.

The Marattiaceae family represents an ancient lineage, with roots stretching back to the Carboniferous period. As the sole surviving family within the order Marattiales and the subclass Marattiidae, they occupy a unique position in the plant kingdom. Unlike the more common leptosporangiate ferns, these are eusporangiate, meaning their sporangia develop from a group of cells rather than a single initial cell. This deep evolutionary divergence is further highlighted by their unusual cellular processes; certain genera, such as Angiopteris and Marattia, are the only known euphyllophytes to undergo monoplastidic meiosis.

The family currently comprises six recognized genera: Angiopteris, Christensenia, Danaea, Eupodium, Marattia, and Ptisana. Their physical diversity is striking. Angiopteris species, native to Australasia and Oceania, can produce fronds reaching up to 9 meters in length. In contrast, the genus Christensenia features leaves that resemble those of a horse chestnut, and while the plants themselves are relatively small, they possess the largest stomata known to science. Other members, like the king fern (Ptisana salicina), provide a tangible link to human history; its fleshy rhizome has long served as a food source for indigenous peoples in the South Pacific.

Taxonomic understanding of these ferns has evolved significantly. While traditional classifications once grouped them differently, modern phylogenetic analysis—such as the 2016 Pteridophyte Phylogeny Group (PPG I) system—has refined our view, splitting the paraphyletic genus Marattia into three distinct groups. Despite their long fossil history, which includes extinct taxa like Psaronius, the post-Jurassic record for the family is notably scarce. Today, these ferns remain a subject of intense study, not only for their unique reproductive biology and explosive spore dispersal but also for their role as a sister group to the Polypodiidae, offering a window into the deep history of plant evolution.

The group's ability to adapt is evident in the spread of species like Angiopteris evecta. Originally introduced to botanical gardens in regions like Hawaii, Jamaica, and Costa Rica, it has since escaped and naturalized, becoming an invasive species. This success is likely aided by their unique method of explosive spore dispersal, a trait not found in other fern groups.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• The secret to the success of 11,000 fern species lies in a single cell
• These ancient spore-bearing plants once towered over Earth as massive, coal-forming forests
• Wood ferns are ancient survivors that have been evolving for 100 million years
• The ancient seed ferns that redefined the Carboniferous period as an age of discovery
• Ferns are closer cousins of roses than of clubmosses
• Why the most important food in Uganda is actually a sterile, ancient clone
• The wild apple forests of Kazakhstan hold the genetic key to our future fruit
• The accidental apple that became a national icon and a tech giant's namesake
• Why one of the world's largest plant orders is a botanical mystery
• The tropical plant family that tricks bees into doing all the hard work
• Why the ancient Magnolia family is a botanical puzzle that defies simple classification
• The surprising history of the melon reveals it is a botanical berry, not fruit.

More in Plants · More in Gardening · Latest · A–Z · All topics