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Pentagramma spp.
Overview
Pentagramma is a genus of small ferns in the family Pteridaceae, known as goldback and silverback ferns, native to western North America. Plants grow from short, scaly rhizomes and produce triangular, two- to three-times-divided fronds 4-12 inches (10-30 cm) long on dark, wiry brown to black stalks. The undersides of the fronds are coated with a powdery yellow or white waxy farina that prints a colored impression when pressed against a surface, giving the group its common names. The genus grows in rock crevices, on dry banks, and among boulders in oak woodland, chaparral, and coniferous forest, often on shaded north slopes that stay cooler in summer. P. triangularis, the goldback fern, is the most widespread species, ranging from British Columbia to Baja California. The fronds curl and dry during summer drought, exposing the colored undersides, and unfurl green again with autumn and winter rains. Reproduction is by spores carried along the veins on the frond undersides. The genus needs sharp drainage and a dry summer rest, and it declines in soils that stay wet through the warm months. Plants are small and slow to establish from spores.
Native Range
Pentagramma is native to western North America, from British Columbia south through California to Baja California and east into the Great Basin and Sonoran regions. Species grow in rock crevices, on cliffs, and on dry wooded slopes, often on shaded north-facing aspects.Suggested Uses
Pentagramma is grown in rock gardens, crevice plantings, and shaded dry-climate gardens of western North America. The small size suits troughs and tucked rock pockets where summer drainage is sharp.How to Identify
Appearance
Size & Dimensions
Height4" - 1'
Width/Spread4" - 10"
Bloom Information
Pentagramma produces no flowers and reproduces by spores. Spore-bearing structures line the veins on the frond undersides beneath the waxy farina and release spores in the cooler, moist months. Fresh fronds expand with autumn and winter rain.
Detailed Descriptions
Foliage Description
green, with yellow or white farina beneathGrowing Conditions
Sun Requirements
Requires 2-6 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Pentagramma grows in part shade with sharp drainage in rocky, gritty soil and a dry summer rest. The genus tolerates drought by curling and drying its fronds, then reviving with cool-season moisture, so summer irrigation can cause rot. Plants suit shaded crevices, rock walls, and the cooler north sides of boulders. Hardiness covers the mild and cold-winter parts of western North America, with most species tolerating light frost. Few pests affect the small fronds. The waxy farina on the frond undersides is normal and not a sign of pest or disease.Pruning
Remove dead or tattered fronds in autumn before new growth expands. Curled, summer-dormant fronds can be left in place, since they revive with rain. No other pruning is needed.Container Growing
Suitable for container growing
Minimum container size: 1 gallons