Home Donate
Research with the Aleutian Shield-fern, Polystichum aleuticum

Reproductive Biology of the Aleutian Shield-fern, Polystichum aleuticum. Final Report by Patricia S. Holloway to the U.S. Department of the Interior, Fish and Wildlife Service. 1994.

A four-year study was conducted to learn if spores of Polystichum aleuticum were viable, to define methods of cultivation for a recovery effort, if needed, and begin exploration of plant variability through isozyme analysis. The conclusions from the study were:

1.Polystichum aleuticum growing on Mt. Reed, Adak, has viable spores that germinate in 6-8 weeks in vitro.

2. Most spores are released in clusters, and multiple germination per cluster is common.

3. Germination occurs on Hoagland's or Knop's solution as well as a peat/sand medium.

4. Optimum agar concentration was 6 g/l or less. Higher levels slow germination rate.

5. Medium pH does not influence spore germination between pH5.75-6.92

6. Soils at Adak site are predominately sandy loam, 6-16% organic matter, pH range 5.6 - 6.4

7. Spores exhibit thermodornancy below 8C and above 20C.

8. Spores require light for germination but intensity between 10 and 50 micro moles per square meter per second does not matter.

9. Any good commercial peat lite potting mix works well for root production and growth after in vitro germination.

10. Mulch with stones to reduce fungus gnat problems and algae growth. Gnatrol and Exhibit biological controls show no phytotoxicity.

11. Fourteen tested individuals showed no genetic variation in isozyme analysis, and there was not variation between P. aleuticum and P. lachenense but sample size was very small


Isozyme comparison of the species Polystichum aleuticum and P. lachenense by David Boyd and Patricia S. Holloway. (Unpublished manuscript, University of Alaska Fairbanks. 1993)

This study showed the results of a preliminary research project to examine the isozyme activity of the Aleutian shield-fern, P. aleuticum and its Asian relative, P. lachenense. We analyzed 14 individuals from Adak Island's single population of P. aleuticum and compared them with a single individual of P. lachenense from Tiachung, Taiwan. Our tiny study showed that the 14 individuals from Adak clearly comprise a single genotype population. All loci were fixed with no indication of variation within the population. Additionally, the isozyme banding for P. aleuticum and P. lachenense were identical. However, we had only one specimen of P. lachenense. Therefore, a lot more data needs to be collected. Lellinger has reclassified P. aleuticum as P. lachenense.


Spore viability and germination of the endangered Aleutian shield-fern, Polystichum aleuticum. by Patricia S. Holloway and David Boyd. (HortScience 28(5):182. Abstr).

Research was initiated in 1990 to study spore viability, spore germination in vitro, and methods of controlled environment culture for the endangered Aleutian shield-fern, Polystichum aleuticum. Spores germinated in 30-45 days on both Knop’s solution and Hoagland’s No. 2 solution in aseptic culture. Germination was most rapid on cultures with less than 6 g/l agar. Cultures with no agar were susceptible to contamination by algae, and sporophyte losses during transfer to greenhouse media were high. Germination rate and subsequent appearance of the first leaf stage did not differ significantly within a medium pH range of 4.7 to 7.0. Spores exhibited a thermodormancy at 25C but germinated well at 18C and required light for germination. Sporophyte transfer from aseptic culture was most successful after true fronds beyond the first leaf stage had developed. A commercial bedding plant mix composed of Sphagnum sp. peat and perlite provided an optimum rooting medium for the ferns.

The University of Alaska Fairbanks Georgeson Botanical Garden, PO Box 757200, Fairbanks, Alaska 99775 (907) 474-7222, gbgardensuaf@gmail.com