Polystichum × bicknellii Hahne, 1904
🇬🇧 Bicknell's Shield-fern
🇫🇷 Polystic de Bicknell
Taxonomy
- Kingdom: Plantae
- Clade: Tracheophytes
- Clade: Monilophytes
- Class: Polypodiopsida
- Subclass: Polypodiidae
- Order: Polypodiales
- Suborder: Polypodiineae
- Family: Dryopteridaceae
- Subfamily: Dryopteridoideae
- Genus: Polystichum
- Hybrid: Polystichum × bicknellii
Presence
Present.
Notes
Hybrid of P. aculeatum (L.) Roth, 1799 × P. setiferum (Forssk.) T.Moore ex Woynar, 1913. Triploid (2n = 123).
This hybrid is very common and occurs in mixed populations of P. aculeatum and P. setiferum. Although it is impossible to create a typical profile of P. × bicknellii, as this hybrid can be morphologically very variable and very close in appearance to one of its parents (Bizot et al., 2016), there are still some good clues to help identify it in the field. The acroscopic basal pinnules are usually very long (15-18 mm), curved toward the rachis, and have a detached auricle. Searching for aborted spores is necessary to confirm the identification, as this hybrid is mostly sterile.
P. × bicknellii is able, in rare cases, to produce viable spores through irregular meiosis, and viable hexaploid (2n = 246) offspring through autopolyploidy (Pintér, 1995). This offspring is technically a new species within the genus Polystichum.
Named after Clarence Bicknell (1842-1918), a British archaeologist and botanist.
Given the absence of spores on the plants pictured below, it was not possible to check their viability. Therefore, they remain potential hybrids and should be treated as such.
Photographs
Sources
Badré, F., & Deschatres, R. (1979). Les Ptéridophytes de la France : liste commentée des espèces (taxinomie, cytologie, écologie et répartition générale). Candollea, 34(2), 379-457. https://doi.org/10.5169/seals-880127
Bizot, A., Holveck, P., Thomas, J.F., & Viane, R. (2016). Biométrie stomatique dans le genre Polystichum en Europe : résultats, enseignements et intérêts. Bulletin de la Société d’histoire naturelle des Ardennes, 105, 44-63.
Pintér, I. (1995). Progeny Studies of the Fern Hybrid Polystichum × bicknellii (Dryopteridaceae: Pteridophyta). The Fern Gazette, 15(1), 25-40.
Prelli, R., & Boudrie, M. (2024). Les fougères et plantes alliées d’Europe (2nd ed., p. 411). Biotope.
Tison, J.M., & de Foucault, B. (2014). Flora Gallica : Flore de France (p. 13). Biotope.