Onoclea sensibilis 'Skeleton' (Hortvs Linearis)

Sensitive Fern Onocleaceae

A fern that appears to have been designed by someone with a rather severe dislike of leaves! Onoclea sensibilis ‘Skeleton’, also known as ‘Hortvs Linearis’, is an extraordinary sport of the Sensitive Fern in which the sterile fronds are reduced almost to their framework of veins. The result is delicate, skeletal and distinctly bizarre—more botanical sculpture than conventional fern.

The species itself is native across eastern and central North America, from Canada through much of the eastern United States, with a separate range extending from south-eastern Siberia through Korea, Japan and China. It is a deciduous fern of wet woodland, swampy ground, stream margins and other permanently moist habitats.

The history of ‘Skeleton’ is unusually well recorded for such a specialist selection. It arose as a sport in a woodland garden, subsequently being selected and introduced into cultivation. A German nursery catalogue describes it as a dwarf, slow-growing form in which the leaf surface is almost entirely reduced to the veins, and records it as a particularly curious plant for fern enthusiasts. The American Fern Society also lists ‘Skeleton’ as synonymous with ‘Hortvs Linearis’, confirming the connection between the two names. (American Fern Society⁠)

In cultivation it retains the characteristic behaviour of Onoclea sensibilis: soft sterile fronds emerge in spring, while the much shorter fertile fronds become dark and bead-like, persisting through winter. The sterile foliage is famously ‘sensitive’ to frost, collapsing with the first serious cold, but the creeping rhizome is considerably tougher and returns reliably in spring.

Unlike the vigorous species, ‘Skeleton’ is slow growing and much more restrained, making it particularly valuable for collectors and for planting where the extraordinary architecture of the foliage can be appreciated at close quarters. Give it moist, humus-rich soil and shade or dappled shade; never allow it to become genuinely dry.

Garden use: A superb collector’s fern for the woodland garden, fernery or shaded trough, where its almost leafless, skeletal fronds can be seen properly. It is an excellent example of how far a fern can depart from the familiar without ceasing to be recognisably itself.

Cultural note: The species has a history of traditional use among Indigenous peoples of eastern North America, including the gathering and cooking of young fronds as a spring vegetable, together with various recorded medicinal uses. ‘Skeleton’, however, is emphatically a plant for looking at rather than eating.

Hardiness: H5 (-15 to -10°C)
Flowering: Fern – no flowers; fertile fronds produced in late summer and persisting through winter
Height: 40–60 cm
Spread: 20–40 cm