Ferns and Fiddleheads

 

A Christmas Fern (Polystichum acrostichoides) in spring. The 
fronds of this fern sprout from the underground rhizome.
Rowan County, North Carolina.  

Ferns are members of an ancient and distinguished lineage. Even today ferns remain significant members of the world’s flora.  Ancient, fern-like plants appeared in the fossil record over 300 million years ago during the Devonian Period. This was when the first land animals and plants emerged, including the ancestors of today’s ferns.  Ferns saw the rise and fall of the dinosaurs and the ascendance of mammals including humans. There are over 10,000 ferns species alive today, most of them living in the tropics.  North America is home to about 380 fern species. 

Most ferns have compound leaves, called fronds.  Compound leaves resemble bird feathers (pinnae) and are thus said to be pinnately compound.  The central vein of the leaf, the rachis, supports the many leaflets.  Ferns reproduce by making spores and certain fronds bear sporangia, the spore producing structures.  The stems of many ferns grow below ground and are called rhizomes.  Rhizomes make the fronds that erupt from the soil.  New fern leaves are tightly coiled when they emerge.  This coiling protects the frond’s delicate, developing leaflets.  As the coil unrolls the leaflets at the base of the frond emerge first and the tip of the leaf unrolls last. These young coiled fern leaves are called fiddleheads because they resemble the scrollwork at the end of a violin’s neck. 

Leaflets of Christmas Fern. The base of each
leaflet has a "thumb" that makes it resemble a Christmas stocking.
Rowan County, North Carolina.

A fiddlehead of Christmas Fern.
Rowan County, North Carolina.

Perhaps the most common fern in our area is Christmas Fern (Polystichum acrostichoides).  Christmas Ferns are found throughout eastern North America and grow in the forest understory.  Their name refers to the fact that the fronds are still green at Christmastime.  Christmas Ferns have pinnately compound leaves that can be over a foot long and may have 20-30 leaflets.  The base of each leaflet has a triangular lobe that is said to resemble a Christmas stocking, further reinforcing the name.  In early spring fiddleheads emerge from the underground stems.  Some fronds have leaflets with brown sporangia on their lower surface.  These spore-bearing leaves are called fertile fronds.  Spores are released into the air and float away, hopefully to establish new Christmas Ferns.  

A fertile frond of Christmas Fern. The dark brown
underside of the terminal leaflets are producing spores.
Rowan County, North Carolina. 

Another common fern of Piedmont North Carolina is Rattlesnake Fern (Botrychium viginianum). This fern has compound leaves and a fertile frond of compact leaflets bearing sporangia.  The common name for this plant comes from the resemblance of its fertile fronds to the rattles on their namesake pit viper.  The genus of Rattlesnake Fern, Botrychium, also includes Grape Ferns. These ferns get their name because the fertile fronds look like little bunches of grapes.  

Rattlesnake Fern (Botrychium virginianum) with a spore bearing 
fertile frond. Rowan County, North Carolina.

Ophioglossum pyncnostichum goes by the common name of Southern Adder’s Tongue.   This small fern is in the same family as Rattlesnake Fern but has a single, simple leaf rather than compound leaves.  The Southern Adder’s Tongue leaf has an upright segment that bears the spores.  The people who named this fern thought this spore making structure looked like the tongue of a snake.  

Southern Adder's Tongue (Ophioglossum pyncnostichum) with its simple 
leaf that is just starting to produce the spore bearing segment.
Rowan County, North Carolina. 

Southern Adder's Tongue with a mature fertile spike.
Rowan County, North Carolina.

Detail of Southern Adder's Tongue spore producing structure.
Rowan County, North Carolina. 

A delicate fern with a delicate name is Northern Maidenhair Fern (Adiantum pedatum).  Its fronds extend in a horizontal, circular arrangement.  Northern Maidenhair Fern grows in the rich woods of the mountains and Piedmont.

Northern Maidenhair Fern (Adiantum pedatum) fronds.  
Davidson County, North Carolina.

Southern Lady Fern (Athyrium asplenioides) and Netted Chain Fern (Woodwardia areolata) both make fairly large fronds and are common in moist woods in the Southeast.  Southern Lady Fern has twice-pinnately compound fronds, that is each leaf has leaflets each of which in turn also bears leaflets.  Netted Chain Fern has compound leaves with leaflets whose blades run along the rachis.

 

Southern Lady Fern (Athyrium asplenioides) fronds.
Rowan County, North Carolina. 

Netted Chain Fern (Woodwardia areolata) frond.
The blades of the leaflets extend onto the rachis in this fern.
Rowan County, North Carolina. 

A very odd fern, Shoestring Fern (Vittaria lineata), is found in south Florida, on Caribbean Islands and in Central and South America. The fronds of Shoestring Fern are simple rather than compound and look like green shoestrings.  Shoestring fern grows as an epiphyte, usually on Cabbage Palm (Sabal palmetto) trunks. 

Shoestring Fern (Vittaria lineata) growing on the 
trunk of Cabbage Palm (Sabal palmetto).
Palm Beach County, Florida.

Another unusual South Florida fern is Acrostichum danaeifolium, the Giant Leather Fern.  It is indeed a giant with fronds reaching over six feet in length.  This fern grows in swamps and marshes throughout southern Florida and into the American tropics.  Fertile fronds bear leaflets with brown sporangia on the underside.  Giant Leather Fern cannot tolerate frost and its northern distribution is limited by freezing weather. 

Giant Leather Fern (Acrostichum danaeifolium) growing in a marsh.
Palm Beach County, Florida.

Giant Leather Fern with sporangia.
Palm Beach County, Florida. 

Hawaii hosts several giant ferns, one of which is the Hawaiian Tree Fern, Cibotium menziessi.  These ferns are truly trees and can reach over thirty feet in height.  They grow on the rainy, windward side of the Hawaiian Islands and are a major trees of the rainforests there.  Hawaiian Tree Ferns have a starchy pith and are eaten by invasive feral pigs and are also threatened by over-harvesting. 

Hawaiian Tree Fern (Cibotium menziessi).
This fern can reach 30 feet in height. 
Hawaii Volcanoes National Park, Hawaii.

Fiddle head of Hawaiian Tree Fern.
Hawaii Volcanoes National Park, Hawaii.

Ferns are found on all continents except Antarctic and they are survivors from deep time.  Ferns range in size from tiny to tree, but all have a distinctive and elegant appearance that is quite appealing.