Appearance
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". 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.
Distribution
"Asplenium onopteris" is found in western and central Europe, the Mediterranean Basin and Macaronesia. There are isolated findings as far north as Ireland and Poland.
Habitat
"Asplenium onopteris" is found in western and central Europe, the Mediterranean Basin and Macaronesia. There are isolated findings as far north as Ireland and Poland.References:
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