Dryopteris affinis (Lowe) Fraser-Jenk., Scaly Male-fern
Account Summary
Native, common, widespread and locally abundant. European temperate.
1858; Smith, T.O.; Ardunshin.
Throughout the year.
Growth form and variation
This is an extremely variable apomictic species of complex ancestry which is divided into four subspecies by Page (1982) and into five morphotypes by Jermy & Camus (1991). Page (1997) reverts to three subspecies, and in the second edition of the New Flora of the British Isles 1997, Stace takes the same approach. Like other entirely asexually reproducing species complexes, D. affinis does not carry out meiosis or reduction division during spore formation, so that its spores are of the same chromosome number as the parent plant. When the spores germinate and produce prothalli, no sexual fusion takes place, so the new sporophyte arises by apogamy (ie an unreduced female gamete, or a cell associated with it, forms the embryo of the next sporophyte generation). It is therefore genetically identical to the original parent plant and the sexual mechanism has been by-passed. Over time, genetic mutations occur, however, and, if the offspring are viable, the mutations are maintained by this method of non-sexual spore reproduction. Eventually, given sufficient time, this produces a multitude of self-perpetuating varieties or 'micro-species' as in this particular case (Jermy & Camus 1991).
These varieties, morphotypes, subspecies or micro-species – whatever we decide to call them, can probably all act as male parents in crosses with other species of the genus Dryopteris, and we do have a limited number of records in Fermanagh of the hybrid that D. affinis forms with D. filix-mas (D. × complexa).
Identification
Despite the above, D. affinis is usually easily separated from D. filix-mas (Male-fern) by the presence of a dark lead-grey or blackish spot at the point at which each pinna meets the rachis, which itself is densely clothed in masses of orange-brown or golden-brown, chaffy scales. The new annual fronds of D. affinis are also produced two to five weeks later than those of D. filix-mas, and their stipes are more densely clothed with chaffy golden-brown or light orange-brown scales (Page 1997).
The three subspecies recognised in New Flora of the BI (1997) are really very difficult to differentiate in a consistent manner, and Robert Northridge and the current author (Ralph Forbes) as joint Vice-county Recorders of Fermanagh, have not tried to distinguish them here. There is certainly more than one subspecies or 'morphotype' of D. affinis present in Fermanagh, although with limited manpower we have not yet been able to differentiate and properly record them. As Page (1997) points out, "satisfactory identification of the variants of this taxonomically very complex apogamous species usually requires a symphony of characters to be taken into simultaneous account."
Preferred habitats
In general, D. affinis occurs in the same wide range of natural and artificial (man-made) habitats as both D. filix-mas and D. dilatata with which it frequently overlaps (Page 1997). These include deciduous woods, along open rides or fire breaks in conifer plantations, hedgerows, streamsides, well-drained places on open hillsides and in mountain glens, plus on or in crevices in urban brick walls.
Toxicity
As with other Dryopteris species, D. affinis contains toxins and is intolerant of grazing pressure.
Fermanagh occurrence
In Fermanagh, D. affinis has been recorded in 345 tetrads, 65.3% of those in the VC. This makes it common and more or less widespread throughout, although it is still scarce in some parts of the lowlands, particularly those with less acid or more base-rich soils. Typical habitats are woods, shaded banks and mountain screes. At higher altitudes, D. affinis certainly appears more common than D. filix-mas which it appears to replace in these circumstances. In Fermanagh, it is very likely that the triploid subsp. borreri (Newman) Fraser-Jenk. will become recognised as the common form of the species, a pattern of occurrence that is perhaps just beginning to appear elsewhere in Britain and Ireland.
British and Irish occurrence
Like D. filix-mas and D. dilatata (Broad Buckler-fern), D. affinis is a long-lived plant, most frequent in the wetter, more ceanic climate of western parts of the British Isles, frequent but more local in the east (New Atlas). It ascends in Fermanagh to moderately high levels, around 300 m on mountain cliffs and screes. Being difficult to identify, the three subspecies recognised by Stace (1997) were poorly recorded during the BSBI Atlas 2000 survey, and they were not mapped in the 2002 New Atlas.
Elsewhere in Ireland, Hackney et al. (1992) listed three subspecies occurring in the three VCs covered by The Flora of the NE of Ireland; subsp. affinis in open situations at all altitudes; subsp. borreri in similar situations to the previous, but also in woodland and more frequent than subsp. affinis at lower levels; and subsp. cambrensis, which is confined to open, upland situations, for example, on mountain cliff ledges and in crevices. D. affinis was not subdivided in The Flora of County Dublin (Doogue et al. 1998), and there are just two individual records by Clive Jermy of subsp. affinis and subsp. borreri dating from 1984 listed in The Flora of Cavan (Reilly 2001). In the Flora of County Waterford, Green (2008) lists nine records of subsp. affinis and two of subsp. borreri made by four different recorders.
European and world occurrence
On account of the taxonomic and nomenclature changes this taxon has gone through in the last 40 years it is difficult to assess the real distribution of D. affinis on a European, let alone a world basis. Nevertheless, it is mapped by Hultén & Fries (1986, Map 65), and regarded by them and most other botanists as a mainly European temperate species.
Names
The genus name 'Dryopteris' was first given by the Greek physician, Pedanius Dioscorides (c. 40-90 AD), to a fern growing on oak trees, and is a compound of the Greek 'dryas' = 'oak', and 'pteris' = 'fern' (Gilbert-Carter 1964). The specific epithet 'affinis' is Latin meaning 'related' or 'similar to', presumably referring to D. filix-mas, the other scaly Male-fern (Gledhill 1985).
Threats
None.