Microsorum musifolium Copel.

incorrectly Microsorium musifolium
 

Common names: Crocodile Fern, Crocodylus Fern

 

Sold with the trade name  Microsorium 'Crocodylus'

 

Synonym:  Polypodium musifolium 
   

Microsorum or Microsorium?  If you located this plant on many websites you may have been confused by the name spelling.  After a good deal of searching plant literature we've discovered (January, 2007) the correct genus spelling is "Microsorum".  With the assistance of the editors of the University of British Colombia plant web site (UBC) we were directed to the Australian Plant Names Index (APNI).  On that site a quote from a Mr. Bosman clarifies the conflict.  The genus Microsorum was originally published in 1833.  Botanist Dr. Link went on to publish papers in 1841 using both the spelling Microsorum and Microsorium (with an "i") in the same paper.  Since that time both spellings have been used by botanists to describe the same genus.  Since you can find both spellings on numerous scientific sites (TROPICOS, IPNI, ePIC and others) apparently either is acceptable.  But, in the purely technical sense, Microsorum is the correct genus spelling (first publication takes precedence).  Two separate genus do not exist.  In this instance, the International Plant Names Index (IPNI) uses only Microsorium musifolium so we have left the spelling as published.

Known as one of the the "Wart Ferns", the genus Microsorum Link consists of approximately 50 species found worldwide.  The genus Microsorum is a part of the family Polypodiaceae.  The species is  epiphytic (grows on trees) but has been observed growing attached to stone. The species was earlier known as Polypodium musifolium but was correctly changed to Microsorum musifolium in 1929 when it was discovered the species did not fit the definitions required to be placed in the genus Polypodium.  Microsorum musifolium was also at one time incorrectly treated as a synonym of Microsorum punctatum (L.) Copel. despite at least eight major differences in the characteristics of the two species, primarily the rhizome surfaces.  The rhizome surface of Microsorum musifolium is not waxy while the rhizome of Microsorum punctatum is often waxy.

We are often hesitant to use the term "rare" when describing many plants.  A rare plant is one that is scarce in nature or somewhat difficult to obtain, not one you can buy on eBay for under $10 almost any day of the year.  When there is evidence a plant is rare we include a "Rare Plant" icon .  There are however a large number of formerly truly "rare" plants that are now being tissue cultured (cloned) and which can be honestly called at least "semi-rare".  Sellers on the web, especially eBay, claim in bold letters Microsorium musifolium (mew-sih-FOH-lee-um)  or Microsorium 'Crocodylus' as sellers love to call it is both new and rare.  Unusual, certainly.  Rare?  Maybe when it was wild in its native rainforest before it was commonly cloned.  But now?  The species is extremely common as a result of the production of hundreds of thousands of specimens in tissue cultuture laboratories.  You can find Microsorum musifolium for sale effortlessly on a dozen websites.  Some sources offer small plants for just a few dollars.  Rare?  No. New?  Hardly.  The species was described to science in 1929.

 

A noted plant website has been leading searchers to believe the name Microsorium 'Crocodylus' is truly a botanical name and the real name (Microsorum musifolium or Microsorium musifolium) is the synonym!   The first name the plant was published under is the accepted botanical name with the exception of learning the original published name was placed in the wrong genus.  All future names that are published in scientific literature (in error) then become synonyms.  Trade names are never considered synonyms! 

 

The name ‘Crocodylus' is a registered trade name given the plant by the company in Australia that first tissue cultured (cloned) the fern.   ‘Crocodylus'  is not part of the plant's actual scientific name and cannot be found in any botanical reference or source.  

 

Microsorum musifolium is a fabulously unusual fern (hardly new since it's been around since the planet was created) that is now commonly available.  This very unique fern has elongated strap-like blades which have the appearance of crocodile scales and is capable of producing a thick bushy plant.  Those "scales" that resemble the scales of a crocodile are known scientifically as clatherate scales. 

 

Our friend Randy King of King Foliage in Homestead, FL introduced us to this unusual specimen.  Randy sent an e-mail and told us one was on its way.  Easy to grow, this fern will soon outgrow a terrarium or vivarium with up to three foot fronds so consider it for a good size pot in the greenhouse or garden provided you live in a warm climate.  The plant prefers moderate to fairly bright light and high humidity but does not grow well if the roots are kept wet.  Avoid over watering!  

 

Microsorum musifolium is said by some to be a "hardy" fern whose fronds contain a labyrinth of darkly pigmented veins which become more conspicuous as the plant ages.  The fern grows from a moderately long creeping rhizome that is capable of climbing.  The frond collects humus, has a thin blade texture,  and produces numerous small sori (spore cases) scattered all over the underside of the frond along the veins.  The plant is a native of  southern Myanmar, peninsular Malaysia, Sumatra, Indonesia, Borneo, Philippines, New Guinea, Thailand and a rainforest valley near Cairns, Australia 

 

Most literature indicates the fern does not appreciate temperatures below 55 degrees.  Some websites say it is actually semi-tropical and can be grown in Zone 7A.  We live in 6B but I wouldn't risk loosing the plant just to find out if it is "hardy".  It can be grown in Southern Florida as a landscape plant in bright filtered light most of the year even though temps sometimes drop quite low.   Experienced South Florida growers recommend bringing it indoors for the coldest part of the winter.  Some large growers near King Nurseries in Homestead have reported major losses when the temperature drops too low in the Miami area making us question whether or not it will grow in Zone 7 or 8.

 

Once established, the plant can easily be divided or, if you are experienced in the collection of sori, grown from spores.  The larger plant in our collection was a gift from the Fort Worth Botanical Garden.