Ferns (class Polypodiopsida) are a diverse class of non-flowering plants that reproduce via spores. Their tender growth with the first rains is a symbolic sigh of relief after the six months of drought characterizing coastal California’s climate. The tightly furled new leaves, also called fronds, are called fiddleheads, named after the spiral shape of the top of violin and resembling a human baby’s tiny fist.
Ferns belong to an ancient lineage, greening up the earth about 200 million years before the dinosaurs dominated. Today, there are over 10,000 species of ferns living across every continent except Antarctica. On an evolutionary timeline, ferns arrived after the mosses, giving them a cutting edge with better developed roots, stems and leaves and a hardier system for moving water from soil to atmosphere. Yet unlike cone-bearing trees or showy flowers with their diverse pollination tricks that evolved millions of years later, ferns lack seeds. Instead, they have microscopic spores dependent on water and wind to disperse. Flip over a frond: the dots lining the leaflets or visible along the edges are called sori, the structures in which the reproductive spores are made. Though often mistaken for a plant disease, sori contain the ferns of the future.
Thanks to their ancient history and great diversity, ferns can be found in a variety of climates and ecosystems. Some species, called epiphytic ferns, grow exclusively on trees. Others prefer rocky, hard-to-reach crevices. In Midpen preserves, you can spot ferns in shaded, damp forest areas.
The adaptability and resilience of ferns make them valuable contributors to their ecosystems. Following significant natural events, such as wildfires, ferns are often one of the first plants to re-establish themselves in the affected area. Their early presence helps establish favorable conditions for other plants to grow, facilitating recovery for the ecosystem.
In addition to wildfires, ferns must also adapt to modern challenges including human-caused climate change. Since 2015, Midpen’s Interpretation and Education Department has teamed up with Save the Redwoods League and local high school students to gather data to learn how different species in redwood forests, including ferns, respond to rising global temperatures. Their efforts combine community science and fern-gazing to discover answers about adaptation and survival for future generations.
Where to find:
According to Calflora, a database of the state’s wild plants, 44 species have been documented in San Mateo and Santa Clara counties, including at Midpen preserves.
- Rancho San Antonio Preserve (Wildcat Loop Trail) – look for the coastal woodfern (Dryopteris arguta), California maidenhair fern (Adiantum jordanii), and goldback fern (Pentagramma triangularis)
- El Corte de Madera Creek Preserve – see if you can spot both the western sword fern (Polystichum munitum) and giant chain fern (Woodwardia fimbriata)
- Picchetti Ranch Preserve (Zinfandel Trail) – try to identify the unique rounded leaves of the coffee fern (Pellaea andromedifolia)
- Purisima Creek Redwoods Preserve – hike among the less common leather polypody (Polypodium scouleri) and Dudley’s sword fern (Polystichum dudleya).