Bay Area Native Ferns

February 5, 2020

When I was deciding on what my final project would be as a Sutro Stewards intern, the plant that kept going through my mind was a fern. Despite knowing some basic identification of ferns, I really did not know that much and yearned to learn more about the ancient plant. My original thought was to try and do a propagation project, however, I quickly was informed that ferns take about a year to go through a reproductive cycle (which I will explore more in-depth later). Subsequently, I decided to investigate ferns; what they are, where they come from and most importantly what native species reside in the Bay Area.

 

Background

Polypodiopsida or fern is one of the oldest groups of nonflowering vascular plants, that can be dated back over 360 million years (Pinson, n/a). The most prosperous era for ferns was during the Carboniferous age. However, many species of ferns from that time period have gone extinct (Fernandez, 2010). Most of the ferns we see today have developed over the past 70 million years, with approximately 10,500 living species. They are the second most diverse group of vascular plants (Pinson, n/a). 

 

Reproduction

A ferns reproduction cycle occurs asexually through the process of two stages, sporophyte and gametophyte. Unlike many plant species that we are familiar with, which reproduce through seeds, ferns reproduce through spores. You may recognize these spores as ‘the little brown dots’ found on the underside of most ferns. 

The sporophyte stage is the visible ‘leafy’ plant that you are used to seeing. The spores in the sporangia, when mature will go through the process of meiosis (cell division producing gametes, that could be sperm or egg). After meiosis, the spore will split open and catapult the sporangia into the wind. Then if all works out for the spores, they will move forward and grow into a gametophyte. 

The gametophyte stage is difficult for one to see with the naked eye. When the spore initially grows into a gametophyte it is about ½ inch in size (about the size of your pinky fingernail). The gametophyte connects itself to the soil through rhizomes (roots). On each gametophyte, there are two important sex organs, the antheridium (sperm) and the archegonium (egg). In order for fertilization to occur there needs to be a decent amount of water because sperm from a nearby gametophyte will initiate germination by swimming into another ferns archegonium. You may be thinking, ‘but why can’t it just germinate itself?’ I thought the same thing. However, for a plant species to thrive in the world, it needs genetic diversity, which is not possible through self germination. Once the rhizoids have rooted themselves enough the gametophytes slowly dissolves leaving the sporophyte to thrive.  


Native Ferns

California Polypody

(Polypodium californicum)

This is a native fern that ranges through northern, central and southern California, mostly along the coast and coastal mountain ranges. Polypodium californicum prefers full shade to partial shade and can be found in or on canyons, streambanks, and north-facing slopes. It grows to about 1.5 ft tall and 3 feet wide. Like most ferns, California polypody is pretty durable and easy to care for. It does well in most soil types as long as moisture is present (even Serpentine). In areas with high moisture all year long, Polypodium californicum will stay evergreen, however, in other drier areas, it will become deciduous. Overall a great fern that is commonly used as ground cover. 

 

 

 

Leathery Polypody 

(Polypodium scouleri)

This native evergreen fern ranges from northern to central California and can be found in fog drip or salt spray zones. A common name for this fern is Leather-leaf, due to the coriaceous or leather-like texture of the leaves. This fern will usually grow up to 6” tall and 1 ft wide. The leather-leaf fern prefers a high amount of moisture in either full or partial shade. A unique characteristic of the leather-leaf fern is that it only attaches and grows from the roots or trunks of living and dead trees. (image taken by Kelly Dodge)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sword Fern

(Polystichum munitum)

The Western Sword Fern is one of the more popular and well-known ferns. It can be found in many areas of western North America, specifically along the Pacific coast. It can be found along wooded hillsides in full shade with low moisture levels. The Western Sword Fern grows easily in most soil types ranging in pH levels 4.0-7.0. It’s dark green fronds of the fern can grow up to 6 ft tall. These fronds grow radially from a tight round base upward and slightly outward. The Sword Fern gets its name by its distinctive sharp pointy leaves resembling a sword. When thinking of companion plants the Western Sword Fern prefers to be with other ferns or under large trees. The Western Sword Fern is a likely host to a few species of moths such as Decantha boreasella, Thallophaga taylorata, and Diarsia esurialis. 

 

 

 

 

Ladyfern

(Athyrium filix-femina)

The Ladyfern is one of the most common and abundant ferns and is widely used for ornamental purposes. It is a deciduous fern that is native throughout most of the temperate Northern Hemisphere. It can be found in damp, shady or woodland areas. Ladyferns growth pattern differs from other ferns in that it is caespitose meaning that instead of the fronds (leaves) growing along a rhizome, they grow out from a central point (clump). The fronds of the Ladyfern are light green with yellow hints in color and resemble that of a light or feathery texture. It enjoys full or part shade and grows best in rich soil with moderate to high levels of moisture. (image taking from calfloranursery) 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Western Brackenfern

(Pteridium aquilinum)

This fern is one of several species of the Pteridium genus. The Pteridium’s are known for their largeness in leaf size and coarseness in texture. Another common name is Hairy Brakfern, a name given due to its trichome stem (rhizome).  The Western Brackenfern can be found in every continent except Antarctica and desert environments. The usual height of the Western Brackenfern varies from about 3.3 to 6.6 ft. It prefers full sun to partial shade with low soil moisture. The perfect soil for the Western Brackenfern is loam soil (fast draining). 

 

 

 

 

 

Coastal Woodfern

(Dryopteris arguta)

Dryopteris arguta is a native fern to the West Coast of North America. The Coastal Woodfern is a beautiful plant that leaves tend to turn in at an angle giving a ruffled or lacy appearance. The color of the Coastal Woodfern is light to medium green. It does well in most conditions preferring anything from full sun to full shade and can be found on sloped terrain. In height, the Coastal Woodfern in most cases will reach 2 ft.  

 

 

 

 

 

California Maiden Hair Fern 

(Adiantum jordanii)

Adiantum jordanii or Maiden Hair Fern is one of the cutest ferns you’ll find. It is a perennial fern native to California and Baja California. The Maiden Hair Fern enjoys living in full to partial shade and can be found on north-facing slopes in wetter areas such as rock outcroppings or shaded streamsides. It will tolerate clay and sand soil types. It should be noted that the Maiden Hair Fern is a host for phytophthora pathogen, commonly known as Sudden Oak Death, and will be hard to find in native plant nurseries.  

 

 

 

Gold Back Fern

(Pentagramma triangularis ssp. triangularis)

This beautiful fern is native to Western North America and can be found through California at elevations ranging from 0-7500. The Gold Back Fern enjoys partial to full shade in rocky sloped areas. (Photos taking from Calflora)   




 

 

 

 

 

 




 

References:

https://youtu.be/WR5PIqOcfKw 

https://www.amerfernsoc.org/about-ferns

https://youtu.be/83KnbZvAzEY 

https://calscape.org/ 

Fernández Helena, et al. Working with Ferns: Issues and Applications. Springer Verlag, 2011. 

Pai, Angela. “Fantastic Ferns and Where to Find Them in Northern California.” Bay Nature, 28 Dec. 2018, baynature.org/article/fantastic-ferns-and-where-to-find-them/.

***Any image not accredited for was taking from Calscope.  

 

 

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