The Propagation and Production of Uluhe fern (Dicranopteris ...

The Propagation and Production of
Uluhe Fern (Dicranopteris linearis)
for Potential Use as a Restoration Species
Ethan Romanchak, Dr. Richard Criley, and Nellie Sugii, UH Mānoa, Department of Tropical Plant & Soil Sciences

A Little Background on Uluhe Fern…
Family:
Binomial:
Gleicheniaceae ‘forking-fern family’
Dicranopteris linearis
Common name: Uluhe fern, False Staghorn
* An indigenous fern
found on all of the main
Hawaiian Islands
* Also native to
tropical Africa, Asia,
Australia, New
Zealand, Polynesia,
and Indonesia

Why Uluhe fern
• There has been an interest from land managers to use uluhe fern as a
restoration species.
• Currently, this fern is not commonly grown for any commercial purpose.
• The Gleicheniaceae family of ferns is difficult to propagate.
• There is potential for this fern to play a role in the landscape industry.
• The fiddleheads of uluhe fern are currently used in the floral industry as
a cut flower accent.

Natural Habitat :
• Wet, open canopy forests.
• Often found on steep slopes.
•Thrives in nutrient-poor, leached soils.
* Covers up to 42,000 hectares in the
Hawaiian Islands.
Growth Habit :
• Climbing, mat-forming due to
indeterminate clonal growth.
• Can form thickets up to 3 meters thick.
* In an area of 1 hectare,
only 2 individual genotypes may exist.

Indeterminate Clonal Growth
Indeterminate growth occurs as fronds
have the potential to continually
lengthen.
Main stipe emerges from an
underground rhizome, then branches at
a 45° angle from the main bud.
Secondary rachises then grow from the
now dormant bud.
This growth pattern continues allowing
the fern to climb steep slopes and cover
large areas with a dense mat continually
growing over itself.

The Role of Uluhe Fern in Hawaiian Ecosystems
• Keystone species in ecosystem succession
(lava flows, landslides, disturbed sites)
• Addition of soil organic matter
(deposits of leaf litter contribute to the Nitrogen and
Phosphorus cycles)
• Resists colonization of invasive species
(light regimes are lowered at the forest floor level)

Now for some Propagation Trials…
Objective:
* To compare propagation from spores versus
vegetative propagation methods for the production
of uluhe fern.

Vegetative Propagation Methods
Layering Trial:
• Vigorous fronds of uluhe fern in the wild
were chosen for layering trials.
• The auxins, IBA and NAA were applied in
differing concentrations of 0, 500 ppm, 1,000
ppm, and 2,000 ppm to the scraped nodal
sections of the rachis.
Layering trial on the rachis of uluhe fern.
• A mixture of moistened peat moss and
uluhe leaf litter were wrapped around the
treated rachis and covered with plastic wrap
then aluminum foil.
• Layers were checked weekly for 8 weeks
and rated for root development.

Vegetative Propagation Methods
Division Trial:
Site of division trial at a landslide.
• Rooted rhizomes of uluhe fern in the wild
with at least two fronds were dug up and
transplanted into 3 gallon containers with
native soil.
• Containers were watered regularly and
monitored for survival for 8 weeks.
Uluhe fern in 3 gallon pot 1 day after division.

Vegetative Propagation Methods
Division Trial Follow-up:
Objective:
Cut rhizome of wild uluhe without disturbance
to the roots.
To determine if division trial
failures were due to vascular
tissue separation from mother
plant or disturbance to root
systems during transplanting.
• Wild plants of uluhe fern were chosen and
rhizomes were cut. Plant section to be divided was
left undisturbed.
• Plants were monitored for survival for 4 weeks.
Uluhe fern, 4 weeks after cutting rhizome.

Life Cycle of a Fern

Spore Propagation Methods
• Fertile fronds of uluhe fern were
collected from the wild.
• Fronds were left on paper for
sporangia to dehisce and spores to
disseminate.
Fertile frond of uluhe fern with deciduous sporangia.
• Spores were separated from
sporangia using plastic wrap, then
placed in folded filter paper.
• Approximately 25 µg of spores were
hydrated in water for 10 minutes, then
sterilized in a 10% bleach solution with
agitation for 20 minutes.
Sporangia and spores of uluhe fern.

Spore Propagation Methods
(cont.)
• Using aseptic techniques, spores were
rinsed with sterile water, then blotted on
sterile tissue.
Individual prothalli,12 weeks after spores were sown.
• Spores were sown on Steeves Medium*
(Steeves 1955) in 90 mm petri dishes, then
placed under 12 hours of light (35
µmol/m¯²/s¯¹) in a controlled environment
(74°C).
*Steeves medium is a modified Knudsen’s medium
(1/2 Knudsen macronutrients, Nitsch 1 microstock,
sucrose, pH 5.7)
• Growth and development was
monitored weekly for 16 weeks.
Young sporophyte in vitro, 2 years after spores were sown.

Results
Vegetative propagation efforts (both layering and division)
yielded no success.
Layering trial:
There was zero adventitious roots formed for every treatment and therefore
zero propagules were obtained.
Division trial:
There was a zero survival rate for all divisions of uluhe fern from wild
plants.
Division follow-up trial:
At the end of the four week trial period, all fern parts that had been severed
from the mother plant were dead.

Results
Propagation from spores yielded many young
sporophytes in vitro.
2 years for
sporophytes to
reach 3cm in
height
2 weeks for spore
germination
2 months for
gametophyte maturity
6 months for sporophyte genesis

Observations and Improved Propagation Procedures
Contamination was Greatly Reduced after Separating Spores from Sporangia.
* Static electricity properties allowed the sparse
spores to be separated from the numerous sporangia.
* Most contamination was due to sporangia trapping
contaminants.
Fertilization and Sporophyte Genesis was Increased Using Life Raft System.
* The ‘Life Raft Membrane Raft’ allows for
gametophytes to generate sporophytes in a humid
culture environment.
* Gametophytes float on a raft over a liquid Steeves
medium.

Conclusions
• Vegetative propagation of uluhe fern is not a viable means
of producing large numbers of propagules that would be
required to service restoration efforts in the Hawaiian Islands.
• Spore propagation of uluhe fern is possible, though the time
required to generate sporophytes is currently a limiting factor in
the production of propagules that would be required to service
restoration efforts in the Hawaiian Islands.

Future Studies on the Propagation of Uluhe Fern from Spores
1) Increasing the rate of gametophyte development, fertilization and
sporophyte genesis.
Medium composition
Nitrogen source in gametophyte media
Gametophyte density
Ontogeny of archegonia and antheridia
2) Procedures for in vivo growth of young sporophytes generated in
aseptic culture.
Culture environmental conditions
Hardening off procedures
Soil media properties
pH
Texture
Mycorrhizal associates

Other Hawaiian Ferns Currently Propagated for the Landscape Industry
Kupukupu
Family:
Binomial:
Status:
Form:
Propagation:
Nephrolepidaceae
Nephrolepis cordifolia
Indigenous
low, spreading with stolons
Division, Micropropagation
Nephrolepis cordifolia
Palapalai
Family:
Binomial:
Status:
Texture:
Propagation:
Dennstaedtiaceae
Microlepia strigosa
Indigenous
finely divided, attractive fronds
Division, Micropropagation
Microlepia strigosa

Other Hawaiian Ferns Currently Propagated for the Landscape Industry
Hapu`u tree fern
Family:
Binomial:
Status:
Form:
Propagation:
Dicksoniaceae
Cibotium chamissoi
Endemic
tree fern, 10 ft tall, 8 ft. spread
Division (from the wild)
Cibotium chamissoi
`Ama`u
Family:
Binomial
Status:
Form:
Propagation:
Blechnaceae
Saddleria cyatheoides
Endemic
small tree fern or terrestrial
Division, spores
Saddleria sp.

Thanks to:
Nellie Sugii
PhD candidate, UH Mānoa, TPSS
Dr. Richard Criley
Graduate Faculty, UH Mānoa, TPSS
Graduate Student Organization
Sources:
Palmer, D.D. 2003. Hawai`i's Ferns and Fern Allies. University of Hawai`i Press, Honolulu.
Russell A. E., J.W.R., Peter M. Vitousek. 1998. The ecology of the climbing fern Dicranopteris linearis
on windward Mauna Loa, Hawai`i. Journal of Ecology. 86: 756-779.
Steeves, T., Sussex, IM, Partanen, CR. 1955. In vitro studies on abnormal growth of prothalli of the
bracken fern. American journal of Botany. 42: 232-245.
Photo Credits:
Alvin Yoshinaga
Dr. Gerrald Carr
Forest Starr
Nellie Sugii