Blechnum penna-marina: Alpine Water Fern

Blechnum penna-marina, the Alpine Water Fern or Little Hard Fern, is a small, creeping, evergreen fern native to the southern hemisphere (New Zealand, Australia, South America). It forms a dense, prostrate mat of simply pinnate, sterile fronds that are dark green and leathery, with fertile fronds that are taller, narrower, and more erect. It spreads by rhizomes to form a tight groundcover.

Plant Profile

This little fern is remarkably tough. It grows in sun to shade, in moist to wet, acidic soil, and tolerates periodic flooding. It is excellent for bog gardens, stream margins, wet rock gardens, and as a groundcover in damp shade. It is hardy to USDA 7-8. The dimorphic fronds (sterile vs fertile) add interest. A great little plant for difficult wet sites.