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Gymnocarpium (dryopteris)

Tara Luna
USDI NPS - Glacier National Park
West Glacier, Montana 59936
(406) 888-7835

Family Scientific Name: Dryopteridaceae
Family Common Name: Wood fern family
Scientific Name: Gymnocarpium dryopteris (L.) Newm.
Common Name: Oak fern
Species Code: GYMDRY
Ecotype: Cedar/Devil's Club habitat, understory species, Glacier National Park, Flathead Co., MT.
General Distribution: G. dryopteris is a circumboreal species, common in moist forests, streambanks, and wet cliffs from lowland to mid-montane elevations.
Propagation Goal: plants
Propagation Method: seed
ProductType: Container (plug)
Stock Type: 800 ml containers
Time To Grow: 1 Years
Target Specifications: Stock Type: Container sporophyte<br> Height: 8 cm, 5 to 7 mature fronds<br> Caliper: n/a<br> Root System: Fully developed rhizomatous root mass in containers.
Propagule Collection: No indusium is present. Collect fronds when spore color is black.
Propagule Processing: Fronds are placed in a room without air movement, spore surface down on butcher paper. Spores will appear as a fine dust on the paper after several days of drying.
Pre-Planting Treatments: Collect spores from thesurface of paper and surface sow in sterilized flats filled with sterile, finely milled peat moss that has been moistened with distilled water. Water spores with distilled water and seal flats with clear plastic wrap to seal in moisture and prevent fungal contamination. Place flats under 60 watt soft incandescent lights set at 12 hour per day illumination. Germination of spores will occur after 15 days. The thread like germ filaments can be seen with the aid of a microscope and will appear as fine green threads on the surface of the medium. A constant temperature of 20 to 25C should be maintained throughout the growth of the prothalli.
Growing Area Preparation/
Annual Practices for Perennial Crops:
Sealed flats are grown under grow lights for 2 to 3 months.They are kept in the greenhouse at 20 to 25C temperature cycle for 3 months, and moved to outdoor shadehouse for 6 months.
Establishment Phase: Spores germinate 10 to 20 days after sowing. The heart shaped prothalli continue to grow for 6 to 8 weeks. Examination of the prothalli under a microscope will reveal the presence of the reproductive structures; the antheridia (male) and archegonia (female), located along the margins and notch of the prothalli. At this stage, it is critical to maintain a thin film of distilled water over the surface of the prothalli for fertilization to occur. It is critical to maintain sterile conditions during germination and establishment. Trays must be inspected for fungal contamination on a regular basis. If fungal contamination occurs, remove infected portions of the medium and treat trays with a highly diluted (1/4 recommended rate)fungicide drench. Treat with dilute fungicide only if prothalli are well developed. Reseal flats immediately and water only with distilled water.
Once sporophytes appear, clear plastic is removed from the trays and asceptic conditions are no longer necessary.
Length of Establishment Phase: 2 to 3 months
Active Growth Phase: Appearance of sporophytes occurred 5 months after spore germination. Individual plantsare transplanted from flats to pots when they are 4 cm tall. After establishment in the greenhouse, they are moved to the outdoor shadehouse in late spring. Plants are fertilized with controlled release Osmocote (13-13-13 4g) and Micromax micronutrients (2g) mixed into Promix medium per 800 ml container. Plants are root tight in containers by fall, one year after germination.
Length of Active Growth Phase: 8 months
Hardening Phase: Plants are fertilized with 10-20-20 liquid NPK at 200 ppm in early fall; pots are leached with water. Plants are watered before overwintering.
Length of Hardening Phase: 4 weeks
Harvesting, Storage and Shipping: Total Time To Harvest: 1 year
Harvest Date: September
Storage Conditions: Overwinter in outdoor shadehouse under insulating foam and snow.
Length of Storage: 5 months
Other Comments: Vegetative Propagation Method: Divisions of rhizomes can be done in early spring with at least 1 leaf shoot or bud per rhizome section and transplanted into containers.
References: Flora of the Pacific Northwest, Hitchcock and Cronquist, Univ. of Washington Press, 7th printing, 1990.
Ferns to Know and Grow, Foster, F.G., Timber Press, 1984.
Glacier Park Native Plant Nursery Propagation Records, unpublished.


Luna, Tara; Evans, Jeff; Wick, Dale; Hosokawa, Joy. 2008. Propagation protocol for production of Container (plug) Gymnocarpium dryopteris (L.) Newm. plants 800 ml containers; USDI NPS - Glacier National Park West Glacier, Montana. In: Native Plant Network. URL: http://NativePlantNetwork.org (accessed 2021/04/11). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

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