Asplenium x tagananaense – still hanging in there!

Asplenium x tagananaense, the hybrid between A. hemionitis and A. onopteris must rank as one of the rarest ferns in the world. A single plant was discovered in 2009 on the island of Tenerife. Despite careful searching only this one plant has been found. While on Tenerife earlier this month I went to see if I could refind it. It is located on a ferny trail near to the village of Taganana after which it is named.

I managed to relocate the fern and although smaller with fewer fronds than on my previous visit in 2009 it appears to be in good health with a new frond emerging.

The two parents are very unlike in frond structure. A. x tagananaense resembles A. hemionitis more closely than its other parent but the lobes themselves are pinnately lobed. I examined the fronds carefully to see if I could recognise any other characters that may indicate its hybrid nature. One small character was fairly obvious – tiny teeth on the cartilaginous margins of the frond. I examined many fronds of A. hemionitis and the margins were smooth or occasionally a few small blunt teeth were found. In the hybrid the teeth were small, but pointed and occurred all round the frond. A. onopteris has an almost undetectable margin without teeth. Mentioned but not emphasized in the original description, this may prove to be a useful diagnostic character although unless other plants are found it is impossible to know how consistent the teeth character is.

It does seem certain that this plant will probably expire in the next few years so if you are in an area where both species occur keep a look out for any odd forms- you never know it may turn out to be the second example of this interesting hybrid.

aAsplenium x tagananaense  - reduced
The sole plant with 2 mature fronds and a new crozier. Note adjacent plant of A. onopteris

aAsplenium x tagananaense frond reduced
Frond upper surface

aAsplenium x tagananaense underfrond reduced
Frond lower surface

aAsplenium x tagananaense teeth reduced
Small teeth on frond margin

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10 thoughts on “Asplenium x tagananaense – still hanging in there!”

  1. Hi.
    I can confirm that this hybrid fern was still alive and well in my two latest visits to the locality in which it grows, made in June 2015 and July 2016. It seems there are no more individuals like this around, but the site is plenty of the parental species. In any case, I observed that someone collected further material (one or two laminae) of A. x tagananaense after its description in 2010, confirmed by comparison of the images shown in the publication with my own photos. It is necessary to avoid such collections, and it is important to point out that the area is under official protection (“Parque Rural de Anaga”), where special permissions for collecting plants are required. Protected natural areas of Tenerife are managed by the “Cabildo Insular de Tenerife”.

    1. Hi again.
      Sorry for this long delay in my reply. I visited again the type locality of the hybrid fern and the only individual seen was still alive, but with its fronds some affected by drought. We have had some Saharan dust in the last weeks and, on the other hand, rains this year were no so good as in 2015 and 2016. I attach one photo of the plant taken on 29th June 2015.
      Best regards.
      P.D.: I’m trying to include one or two photos from my files, but it’s impossible for me to upload them here.

  2. Hi again.
    Sorry, I attach now one photo of Asplenium x tagananaense, taken on 29th June 2015.
    Best regards.

  3. Tim must have taken his picture (above) shortly before February 2015 and it looks very similar to your picture of June 2015
    Could you upload your pictures of 2016, and, if I understand you correctly 2017?
    You should try to make the pictures no bigger than 900 x 600 pixels

    My pictures from 2009, before we named the fern: 1, 2 & 3

    You can see my pictures taken in 2012: 1, 2 & 3. This was the last occasion I visited Tenerife

  4. Hi again.
    Sorry, but I don’t have further photos from 2016 or 2017. I could see the fern in question, but nothing more. And thanks for your pictures, which I’ll check later…
    Best regards from the Canaries.
    P.D.: Is there any new publication about Asplenium x tagananaense, after its formal description in 2010? I’m reviewing literature about ferns of the Canary Islands from some years. Thanks in advance for your response.

  5. Hi Ruben
    I relocated and photographed the single known plant of A. x tagananaense in January 2015.
    I far as I am aware the only publication since 2010 is mine in Pteridologist Volume 6 Part 2 (2015) pp. 162-164 where I describe the original finding and my re-finding.

    1. Dear Tim and Andrew,
      Many thanks for the information and especially for the link to the article in PTERIDOLOGIST, very interesting. I visit this place once a year, mainly to see ferns and to take photos of them in the field. By the way, I have published a small text on the ferns of the laurel forests of Tenerife, as part of a recent book of Drs. Phlip and Myrtle Ashmole, entitled NATURAL HISTORY OF TENERIFE. I attach a first version of the pdf file of such text. It’s only a short chapter, but I hope you like it…
      Best regards from the Canary Islands, and thanks again for your kindness,
      Rubén

  6. Hi again.
    Sad to say that in the latest visits (July 2018 and July 2019) to the locus classicus of the hybrid Asplenium x tagananaense we couldn’t find the fern in question. It’s clear that someone collected the entire plant of the individual found some years ago in the laurel forest above Taganana. It’s a pity and a great loss for the local biodiversity.
    Best regards from the Canaries.

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