Epithet means "from Cambria," an old name for Wales.
Wintergreen (summer dormant), 4 to 24 in. (10 to 60 cm).
Zones 6 (when heavily winter mulched) to 9.
description: The rhizome is short- to long-creeping. Stipes are one-half of the frond length, and the apple-green pinnate blades are ovate with the second from the bottom pair of pinnae the longest. The 12 to 18 pairs of pinnae are frequently serrate. Sori without indusia are round and pregnant with bright yellow spores when ripe. The species and all cultivars are summer dormant (perhaps reflecting an adaptive response to its developmental years in summer hot and winter wet Mediterranean climates), producing a flush of fronds in late summer to fall. They offer dependable sprays of fresh greenery throughout the winter and die back in early to late spring.
range and habitat: In its native southern European and British habitats it is found in mortared walls, especially on antiquities, as well as occasionally in well-drained limestone soil and even on oak trees.
culture and comments: Linnaeus gave the name Polypodium cambricum to what is now known to be a fringed form of P. australe. However, as the original botanical epithet has precedence, the species and all of its cultivars are currently considered correctly classified as P. cambricum rather than P. australe. Confusing, yes, but by whatever name they include some of the most desirable and interesting polypodium variations. Although they tend to prefer limey sites ("that difficult corner in the garden where the builders left all their rubble" [Rickard 2000]), the species and most all of the available cultivars will happily acclimate in traditional moist, ferny loam. I like to display the most unusual types in hanging baskets where they can be shifted about seasonally depending on whether or not they are dressed in foliage.
British collectors have selected and named a portfolio of varieties, some having been formerly classified under Polypodium vulgare. These cultivars yield visual delights and ease of maintenance to the gardener, although all selections will be without their greenery in the summer months. Many are sterile and not reproductively available except by division. Ah, but tissue culture is on the horizon and ideally will enrich our commercial options. While many cultivars are featured in British and European gardens, only a few of the most easily propagated selections are in circulation in the united States.
Barrowii Section (after T. Barrow) has exceptionally thick ovate foliage with some forms having twisted pinnae. It is a member of the Cambricum Group.
Cambricum Group (from Cambria [Wales]) includes a selection of sterile cultivars. All are old, having been discovered
prior to 1894. Typically the fronds are thin-textured and have varying degrees of laceration. Some also have twisted foliage.
'Cristatum' (crested) has pinnatifid fronds with the segments and apex crested. The terminal crest is narrower than the blade.
'Grandiceps Fox' (large-headed, discovered by Mrs. Fox in 1868) is heavily crested at frond and pinnae tips, wherever a fern could possibly be crested.
'Omnilacerum Superbum' (superbly torn) arches gracefully from a basket or the top of a wall with 18-in. (45-cm) fronds that have lacerated pinnae along their length. It is a fertile cultivar.
'Prestonii' (after Preston, who discovered it) has slightly twisted, ovate, thin-textured foot-long (30-cm) fronds and a delightfully entertaining tale of its discovery. "Found in ... north Lancashire in 1871 It was growing in a block of limestone pavement and Preston could not extricate it, so he took the whole block home and gradually grew the fern out of its crevice" (Rickard 2000). It is a sterile, elegantly lacerated cultivar. It is in the Cambricum Group.
Pulcherrimum Group (beautiful) includes an assortment of thick-textured cultivars with ruffled, shredded pinnae supported by narrow, simple stipes on bipinnatifid or tripin-natifid fronds. These are occasionally fertile and, unlike the similarly structured Polypodium xmantoniae 'Cornubiense', do not randomly produce reverted fronds.
'Richard Kayse' (after Kayse, who discovered this fern) was found in 1668 on a limestone cliff where it still grows today in Wales. It was the type plant named Polypodium cambricum by Linnaeus, and many would hope that it could be revised giving P. australe as a proper designation. However, this cultivar is one of the most beautiful of the many cultivars and also one of the most difficult to describe. The 18-in. (45-cm) blade is bi-pinnate with the pinnae simple at the point of attachment to the rachis and then blossoming into fringed pointed tips. They overlap giving a stunning layered effect.
'Semilacerum Falcatum O'Kelly' (half lacerated and falcate, discovered by O'Kelly) is a departure from the heavily cut types. The foot-long (30-cm), slightly incised, sickle-shaped pinnae curve strongly toward the apex of the frond.
'Wilharris' (after Wilharris or perhaps William Harris, curator of the Bristol Zoological Gardens) has narrow, leathery, foot-long (30-cm) fronds with lacerated pinnae. It is easily confused with 'Prestonii' when young or poorly grown. Old plants are more robust than similarly senior plants of'Pre-stonii'. 'Wilharris' belongs to the Cambricum Group.
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