Sword Brake (Pteris multifida), a spontaneous and covert colonist of Melbourne infrastructure.
Although this fern is listed in Flora of Victoria as being known from just one location (likely lost) in the city’s south east, this channel has already featured an undocumented colony in Northcote. Now here is another small occurrence of Sword Brake, in a different suburb, circumstances and material geology. For future record, this niche faces northeast. There is also a seedling Eucalypt in the niche, just to confuse things.
Native to East Asia, Pteris multifida is known to have naturalised in the southeastern United States and California, and in South American and Caribbean cities. In these places, botanists have often identified cultivar forms (particularly those which have ‘crested’ leaves), alongside the type species, as having made the jump to local independence. Notably, the species is reported as growing in a variety of geophysical conditions, including on calcareous walls and in terrestrial soil, with a key detail being the presence of dependable seeps.
We can reasonably say that the fern, although certainly uncommon, is naturalised and underrecorded within metropolitan Melbourne and perhaps at other places across the state. Exotic ferns are a low priority for most of the activities that generate modern botanical records, and the plants’ specialised requirements make it quite possible that the vast majority of occurrences state-wide are on artificial structure. However, with brick, steel and concrete now all confirmed media to add to the Rucker’s Hill bluestone, a variety of structures present themselves as appealing candidate hosts for Sword Brake, including gutterboxes and building fascia where AC drainage provides sufficiently regular moisture.
This is also now the second railway site associated with Sword Brake (the original records were made by the RBG’s Val Stajsic at the Gardiner Railway Station before those platforms were lowered and reconstructed in 2015), making it likely to be lurking around further track structures.