Polystichum acrostichoides aka Christmas Fern

Polystichum acrostichoides is an evergreen fern known as Christmas fern. Its native range runs from eastern Canada to northeastern Mexico. It grows in woods, beside streams, and on rocky slopes. This perennial forms clumps from a branching rhizome. Garden plants reach about 1–3 feet [0.3–0.9 metres] tall and wide. RHS gives an upper size of 3.3 feet [1 metre]. Clumps grow wider over time, but spread slowly.

The long, narrow fronds arch out from the plant's centre. Their dark green blades feel firm and leathery. Each pinnate blade has narrow leaflets along its central stalk. The leaflets have toothed edges and a stocking-like shape. New fiddleheads emerge in spring with pale, silvery scales. Fertile fronds stand taller and have narrowed tips. Sori form beneath the leaflets near those tips. These structures hold spores, which allow the fern to reproduce. It has no flowers or fruit. Fertile fronds die in winter, while sterile fronds stay green.

Grow this fern in partial shade or full shade. It suits cool soil with plenty of organic matter. Moist soil with good drainage supports growth, but drier sites also suit it. The plant tolerates drought and shallow, rocky ground. RHS lists clay, loam, and sand as suitable soils. It also accepts acid, neutral, or alkaline soil. Chicago Botanic Garden lists USDA zones 4–8. RHS rates its UK hardiness as H5. Plants may take five to ten years to reach full size.

Use it in woodland beds, shaded borders, or containers. Its green winter fronds add interest beneath shrubs and near walls. Grouped plants help hold soil on slopes, including dry, rocky sites. Deer and rabbits tend to leave it alone. Songbirds shelter near the fronds and gather material for nests. Most plants need little upkeep and suffer few pest problems. Remove dead or damaged fronds in early spring. Poor drainage can cause crown rot, with winter a risk period. Watch for Florida fern caterpillars.

Plants For A Future lists young fronds as edible. It gives them a low food-use rating and urges caution. That source reports no known toxicity for this species. This does not establish that eating it is safe. ASPCA lists it as non-toxic to dogs, cats, and horses. Historical root remedies also appear in the evidence. Those records do not establish their safety or effectiveness.