Pteridium species

NOTE: This page Last Updated 15 June 2024

According to current taxonomy, Pteridum aquilinum is retained as a species of Europe, and does not occur in the Americas.
The North American Brackens have what is called the Latiusculum morphology, and at least five years ago some taxonomists in the Americas began using Pteridium latiusculum for the American Brackens. [However, none of the North American varieties are listed on iNat under Pteridium latiusculum. see comment below.] Other taxonomists have gone further, and raised the sub-species of the Americas to species rank, but not under Pteridium latiusculum. Based on my lengthy review of iNat observations, it is apparent that at two North American taxa blend seamlessly together at zones of introgression, namely Pteridium aquilinum latiusculum and Pteridium aquilinum pseudocaudatum.

In Eastern Europe, there is a Bracken with Latiusculum morphology very similar to Pteridium aquilinum latiusculum, namely Pteridium pinetorum. It, however, hybridizes with Pteridium aquilinum aquilinum, and intermediates are common where the two co-occur.

Until taxonomists establish the following taxa on iNaturalist

  • Pteridium latiusculum japonicum (available on iNat)
  • Pteridum latiusculum latiusculum (available on iNat as Western Bracken)
  • Pteridium latiusculum pinetorum
  • Pteridium latiusculum pseudocaudatum

  • Pteridium latiusculum pubescens
    it hinders full identification to assign Pteridium latiusculum to a Bracken.
    [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=127416]
    [It would perhaps be interesting to learn whether Pteridium pinetorum predates Pteridium latiusculum, or vice versa]
    - - - - - - - - - -
    A recent, worldwide study of Pteridium: https://bsapubs.onlinelibrary.wiley.com/doi/pdf/10.1002/ajb2.1365
    - - - - - - - - - -
    GOALS of this journal page/project:

  • For each species of Pteridium listed by Plants Of the World Online (POWO) [https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:17210050-1#children], provide at least one link to an iNat observation that is "iconic" (in some way) for that species.

  • Review details of said observations, and deduce diagnostic morphological traits for the identification of each species.
    No doubt, knowing where the fern was observed will greatly assist in its identification.
    - - -

Pteridium aquilinum aquilinum [Western Europe], diploid, 2n

Pteridium arachnoideum [South America, Centra America, Mexico], diploid, 2n

Pteridium brownseyi

  • no iNat observations yet (06 July 2023)
    - - -

Pteridium aquilinum capense [South Africa], diploid, 2n

Pteridium caudatum

The original illustration:** https://www.flickr.com/photos/biodivlibrary/16089999985/
[Notes: It is my perception that in Florida, Pteridium caudatum hybridizes with Pteridium aquilinum pseudocaudatum, and it is this that blurs the demarcations between the two taxa. [I think the original illustration is probably of such a hybrid.] The hybrids would be triploid, thus sterile, but still very capable of vegetative reproduction typical of Pteridium. It is becoming my habit (11 June 2024) to only identify as Pteridium caudatum the very airy, tall, expansive fern of Central Florida. Any putative hybrids (as I perceive them) I assign to Pteridium aquilinum pseudocaudatum. However wrong that may be, it is easier than creating yet another taxon designation for the already burgeoning taxa of Pteridium]

Pteridium central-africanum [Central Africa, of course]

Pteridium aquilinum decompositum [Hawaii], diploid, 2n

Pteridium esculentum [Tropical & Subtropical: Asia -> Australia -> South America], diploid, 2n

Pteridium falcatum

Pteridium aquilinum feei [Mexico], diploid, 2n

Pteridium latiusculum japonicum [Japan, Southeast Asia], diploid, 2n
[Notes: latiusculum morphology, similar to Pteridium aquilinum latiusculum]

Pteridium aquilinum latiusculum [Eastern North America; replaced along the American Gulf Coast and Southeast Atlantic by Pteridium latiusculum pseudocaudatum; a look-alike in Southeast Asia and Japan is Pteridium latiusculum japonicum = Pteridium japonicum ] diploid, 2n

ASIDE: iNat has recently coined the common name of "Western Brackenfern" for this species. Well, "Western Brackenfern" occurs in Eastern North America. So this common name is bound to cause a lot of confusion. [EDIT: 21 November 2023: gcwarbler reported that, after reading this "Aside", he took action and removed the iNat Common Name for Pteridium latiusculum. Now, at least, there will be less confusion regrading this species. Thank you gcwarbler. EDIT 16 November 2023: With incessant insouciant inanity, curators of iNat have resurrected the abominably confusing common name of Western Bracken Fern. Weary am I, indeed.]

Pteridium lineare

Pteridium pinetorum (see cautionary statement in Note below)

[Notes: (1) Has Latiusculum morphology - does not form tall, multitiered fronds; (2) Pteridium pinetorum is smaller than Pteridium aquilinum, emerges later than Pteridium aquilinum, and is associated with pine forest https://www.ebps.org.uk/wp-content/uploads/2014/04/Pteridium.pdf; (3) Caution: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856829/ "The “northern” species (Pteridium aquilinum) has distinct groups at the continental scale (Europe, Asia, Africa, and North America). The northern European subspecies pinetorum appears to involve admixture among all of these."

Pteridium aquilinum pseudocaudatum [primarily Coastal Plains and near-shore of Southeastern North America], diploid, 2n

Pteridium aquilinum pubescens [Western North America], diploid, 2n

Pteridium revolutum [Subtropical & Tropical Asia & India to NE Australia]. diploid, 2n
synonym, Pteridium aquilinum wightianum
https://www.inaturalist.org/observations/197064936 - 2 photos
https://www.inaturalist.org/observations/195082730 - 8 photos
https://www.inaturalist.org/observations/193790491 - 4 photos
[Notes: when young/small, a resemblance to Pteridium aquilinum of western Europe. However, when large mature fronds are produced, they resemble Pteridium arachnoideum in having a winged rachis, long terminal lobes, and sub-leaflets with long lateral lobes near perpendicular to the mid-vein]

Pteridium rostratum [south peninsular Asia through Malaysia to Eastern Australia - and Central Florida], tetraploid, 4n
synonym,Pteridium semihastatum

Pteridium yunnanense

My perception of life forms
is that what we think of as separate species
are in fact connected to one another
in a fluid way,
in the same way that there is really only one ocean on the planet,
and that what we for convenience call the Atlantic Ocean and Pacific Ocean et cetera,
to suit our needs for navigation and orientation,
are in fact one connected mass of water.

In the same way that we divide up the ocean for our convenience of understanding place,
taxonomy draws artificial lines across continuums of interconnectedness between genetically interchanging populations,
and creates categories meant to guide human understanding of the diversity of life forms.

Nature has no concern
nor regard
for the artificial taxonomic devices of human kind.
Nature gets on with what it does,
and is,
in all of its myriad forms of life.

Posted on 06 de julho de 2023, 02:31 PM by mjpapay mjpapay
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