Asplenium onopteris

Asplenium onopteris is known as the Irish spleenwort[1] or western black spleenwort. It is difficult to identify compared with the black spleenwort, Asplenium adiantum-nigrum. The main difference is that A. onopteris is diploid and is one of the two parents of the tetraploid A. adiantum-nigrum (the other being the diploid A. cuneifolium). Armed with a microscope, the most consistent observable difference between A. onopteris and A. adiantum-nigrum is that A. onopteris spores have a mean diameter of 28 μm and are almost all smaller than 31 μm, whereas those of A. adiantum-nigrum have a mean diameter of 34 μm and are almost all larger than 31 μm. The leaflets of typical A. onopteris are narrower in relation to their length than those of typical A. adiantum-nigrum, but this is not a reliable means of identification.[2]

Irish spleenwort
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Class: Polypodiopsida
Order: Polypodiales
Suborder: Aspleniineae
Family: Aspleniaceae
Genus: Asplenium
Species:
A. onopteris
Binomial name
Asplenium onopteris

Taxonomy

A global phylogeny of Asplenium published in 2020 divided the genus into eleven clades,[3] which were given informal names pending further taxonomic study. A. onopteris belongs to the "Onopteris subclade" of the "Pleurosorus clade".[4] The Pleurosorus clade has a worldwide distribution; members are generally small and occur on hillsides, often sheltering among rocks in exposed habitats. The Onopteris subclade has Aspidium-type gametophytes.[5] Its closest diploid relative within the subclade is the North American A. montanum.[4]

Distribution

Asplenium onopteris is found all around the Mediterranean Sea, including North Africa. There are isolated findings as far north as Ireland and Poland.

References
  1. "BSBI List 2007". Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-01-25. Retrieved 2014-10-17.
  2. "Asplenium onopteris (Irish Spleenwort)" (PDF). Archived from the original (PDF) on 2012-10-28. Retrieved 2012-02-22.
  3. Xu et al. 2020, p. 27.
  4. Xu et al. 2020, p. 30.
  5. Xu et al. 2020, p. 46.
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