Recognition: medium to largish ground fern, with narrow and dull fronds. Easily distinguished by the numerous bulbils, or ‘chickens’, borne on the uppersides of the fronds. These are vegetative growths that can develop into separate clonal individuals.
Distribution/ecology: only found in New Zealand. In forest throughout except absent from the eastern South Island. Occurs in wet habitats, around streams and in seepages.
Relationships: very similar to Asplenium gracillimum which has a more diamond shaped frond, more distantly set frond segments, and fewer bulbils (and twice the number of chromosomes). The two frequently hybridise and individuals can be difficult to identify. While they often occur together, hen & chickens fern extends to wetter habitats and Asplenium gracillimum to drier (e.g., hillsides).
There are about 600 species of Asplenium in the world, with some 21 species indigenous to New Zealand. Ten are only found in New Zealand, while most of the others in New Zealand are also in Australia, and a few are widespread beyond. All are characterised by the herring-bone arrangement of the sori (the aggregations of the spore-producing sporangia).
Other common New Zealand Asplenium include:
• shining spleenwort (Asplenium oblongifolium) with once divided, glossy fronds, occurring in lowland and mid-altitude forest of the North Island and northern South Island.
• shore spleenwort (Asplenium obtusatum) with once divided, dull fronds, which is frequent in some coastal parts of the South Island.
• sickle spleenwort (Asplenium polyodon) with once-divided fronds and sickle-shaped, toothed frond segments, in forest throughout.
• hanging spleenwort (Asplenium flaccidum) which is usually an epiphyte, with twice divided, dull, pendulous fronds that occurs in forest throughout.
The common name of spleenwort for Asplenium comes from an old European belief that some of the species there were good for the spleen (wort meaning plant or herb).