Blechnum fluviatile is a really unusual evergreen fern from New Zealand that has very distinctive pinnae. The sterile green fronds, up to 50cm long, are practically horizontal with the brown sporing fronds being erect in the centre of the crown. The scales on the rachis are dark brown and very distinguishing.
It will form a small, very slender trunk over time. Like many of the New Zealand natives, it prefers a damp sheltered site and will form a very attractive clump (spreading rhizomes) over time.
I have it at the base of a Dicksonia fibrosa and it provides all year interest. It has proved hardy to date and an easy fern to grow.
Hardiness: Hardy to -6 Celsius in sheltered areas. Avoid, id possible, planting in ground that freezes hard for prolonged periods. It unexpectedly survived the 2 winters of 2010 where it experienced lows of -10.