Review of Two Non-Native, Invasive Climbing Ferns (Lygodium japonicum and L. microphyllum), Sympatric Records and Additional Distribution Records from Florida

2010·6.2 MB·English

by  Jeffrey T Hutchinson

SHORTER NOTES
USA.
Voucher: Alabama. Jackson County: Near Stevenson. Three miles
Monument
south of Russell Cave National and mi
2.5 northwrest of U.S.
Highway
Approximately 100 mature and
72. fronds 50 individuals
v^^ere
m
growing on wet
a flowstone wall of a vertical cave approximately 6 below
m
The
the entrance. overall depth of the cave reaches nearly 60 with
the
surface entrance located 925 m) above GPS
(282 sea coordinates
level.
ft
#SP107
withheld. July 10, 2009. Barger (AUA, JSU, TROY).
The
authors thank Curtis Hansen and Jack Short along with the anonymous
comments
reviewers
for their helpful in crafting this manuscript. Special thanks
Dan
are extended to Spaulding for his expert assistance with plant specimen
identification and to Misako Nishino and John Kartesz for verification of county
map.—
record data and the Wayne
distribution T. Barger, Natural Heritage
Alabama
Section, Department Union Montgom-
of Conservation, 64 N.
Street,
AL, 36130 Alan
ery, U.S.A., Cressler, U.S. Geological Survey, 3039 Amwiler
Road, Suite 130, Peachtree Business Center, Atlanta, GA, 30360 U.S.A., Brian
D. Holt, Natural Heritage Alabama Department
Section, of Conservation,
Union Max
64 N. Street, Montgomery, AL, 36130 U.S.A., and Medley, 519 W.
GA
Hawthorne
A-13, Dalton, 30720 U.S.A.
Two
Review
of Non-Native, Invasive Climbing Ferns [Lygodium japonicum
and
L. microphyllum), Sympatric Records and Additional
Distribution
Two
Records from Florida—
non-native species of climbing Lygodium
fern,
japonicum
(Thunb.j Swartz and microphyllum
L. (Cav.) R. Br. are currently
many
present in Florida and are highly invasive in natural areas of Florida
(Gordon, Ecol. Appl. 8:975-989. Langeland and
1998; et al, Identification
Biology Nonnative
of Plants in Florida's Natural Areas {2"^* edition]. IFAS
Communication
Services, University of Florida, Gainesville, FL. 2008). Both of
these non-native ferns have become problematic land mangers
to in natural
areas of Florida (Hutchinson Old World Climbing Fern [Lygodium
et
al.,
microphyllum] Management
Plan South Water Manage-
for Florida. Florida
ment West Palm
District, Beach, FL. http:// www.fleppc.org. 2006; FLEPPC,
Florida Exotic Plant Pest Council's 2007 Invasive Plant Species Available
List.
on
http://www.fleppc.org/list/07list.htm. Both
at: 2007). ferns exhibit inde-
terminate growth growing and
horizontally forming complete
vertically, often
From
cover over native vegetation. 2005-2006, the total costs associated with
control of upland invasive plants on Florida public lands
counties,
(cities,
and was
state federal) 9.4 million dollars (FLDEP, Florida Department
of
Environmental Bureau Upland Management
Protection, of Plant (http://www.
dep.state.fl.us/lands/invaspec/2ndlevpgs/Uplandsplntman.htm). The
2009).
and
Florida Fish Wildlife Conservation Commission's Bureau
of Invasive
Management
Plant currently ranks Lygodium microphyllum
(Cav.) R. Br. along
with
hydrilla [Hydrilla verticillata Royal] as priorities research
(L.f.) its for
funding on methods
control (Schmitz, Nat. Areas 27:251-253.
2007). In 2008,
J.
AMERICAN FERN VOLUME NUMBER
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100
(2010)
1
microphyllum and flexuosum Sw. were recommended
L. be
L. (L.) to listed as
Federal Noxious Weeds (USDA, Weed
Risk Assessment. United
States
Department Animal and
of Agriculture, Plant Health Inspection
Service,
While
Raleigh, N. C. 2008). L. flexuosum is not currently present in the U.S.A.,
has
similar biological long distance
it traits (i.e., dispersal, ability to self-cross,
now
fire tolerance) as both species of Lygodium present in Florida (Lott et
al..
Am.
may
Bot. 90:1144-1152. 2003) and be considered ornamental use
for
J.
(USDA, The
2008). goals of this study were to examine the historical records of
both climbing ferns currently present in Florida based on herbarium
records,
new
report on sympatric records, and document new distribution records from
and
north south
Florida.
The known
herbarium microphyllum
earliest record of in Florida from
L.
is
Davenport in Polk County from January 1958 (Florida Division of Plant
6,
#
Industry, Record 0-3753). This report was for a specimen Hollybrook
at
Nursery indicating the fern was present in Polk County The
at this time.
specimen was
turned because fungus on upper
in of a the surface of the
may
pinnae. This indicate that the nursery was cultivating the fern there was
if
concern about the fungus or that they discovered a plant with a disease and
wanted The
identification. report suggests using Dithane Z-78
to control the
fungus but no other details exists in the report. The second earliest herbarium
record for microphyllum was reported February 1958 (FLAS #P5100)
L. 11,
from a nursery in Delray Beach, Florida on the southeast There was no
coast.
more
information on this sample, but the plant was growing in a nursery
was
indicating that being propagated or possibly arrived accidentally with
it
other These two microphyllum was
plants. reports indicate that present
L. in
km
two
1958 at different locations in Florida that are ca. 240 apart. Old World
climbing fern has spread across the landscape of Florida rapid
at a rate since
that time (reviewed in Pemberton and Ferriter, Amer. Fern 88:165-175.
J.
>
1998). This species has been present in Florida for 50 years and was
first
documented
as naturalized in southeast Florida in 1965 (Beckner, Amer. Fern
58:93-94.
1968).
J.
Based on herbarium records, japonicum has been present in Florida
L. for at
The
least 77 years. earliest herbarium record of japonicum was from Polk
L.
County (USF
in 1931 Accession #175179). widely scattered throughout
It is
Florida from the panhandle extreme south Florida. The herbarium
to earliest
from panhandle
records the region of Florida are from 1948-1950. This species
occurs throughout the southeast United States and has likely been introduced
into Florida multiple times. Except for herbarium records, information
little
on japonicum was
exists L. in Florida. In northern Florida, reported that pine
it
straw used mulch contained japonicum and
for L. spores this has increased the
dispersal and spread of the fern (Zeller and Leslie, Wildland Weeds. Summer:
6-9. 2004). has been reported to form dense cover over native ground and
It
shrub plants in both disturbed sites and natural areas of northern Florida
(Langeland
2008).
et
al.,
Based on herbarium records, Polk and Highlands Counties
in south-central
known
were japonicum and
Florida the of both microphyllum
first sites L. L. in
SHORTER NOTES
59
A
Florida. 1935 record (FLAS P3270) japonicum
exists for L. from the Florida
Botanical Garden and Arboretum in Highlands County which became
later
Highlands
part of State Park. In 1973, a park service biologist documented
L.
microphyllum Hammock
as naturalized in Highland Park (FLAS
State P7718).
In a 2004 aerial surveys of Highlands and Polk Counties along Lake Wales
the
Region
of south-central Florida, 213 locations with Lygodium were
spp.
documented with some
infestations of microphyllum 40-80 ha
L. as large as
Wildland Weeds
(Biehl,
7(3):4-5. 2004).
In a survey of Florida from 1927-1930, no Lygodium
flora reports of spp. were
documented Am.
(Moldenke,
Midi. Nat. 32:529-590. 1944). Since the
1930's,
two
non-native species of climbing japonicum and
microphyllum,
fern, L. L.
have been documented from herbarium
records in Florida (FLAS, University of
Herbarium
Florida
(http://www.flmnh.ufl.edu/herbarium/).
Gainesville, Flor-
FSU,
ida. 2008; Florida State University Herbarium
(http://herbarium.bio.fsu.
edu/index.php). Tallahassee, Florida. 2008; FTG, Fairchild Tropical Gardens
Herbarium
(http://www.virtualherbarium.org/default.html). Miami,
Florida.
Wunderlin and
2008; Hansen,
Atlas of Florida Vascular Plants (http://www.
plantatlas.usf.edu/). Institute for Systematic Botany, University of South
Tampa.
Both
Florida, 2008). species are listed as Category invasive
species
I
by
the Florida Exotic Pest Plant Council
indicating they are disrupting natural
communities by
displacing native plant species and interrupting
natural
processes (FLEPPC, 2007). The Florida Department of Agriculture and
Consumer
Services prohibit the sale, propagation, or possession of both
L.
japonicum and microphyllum
(FDACS,
L. in Florida 2009). There some
is
documentation two
of these non-native ferns occurring within the same
habitat
May
in close proximity. Prior to 2000, both japonicum and microphyllum
L. L.
were documented Manatee
in Little River State Park (Myers and Wunderlin,
Castanea 68:56-74.
2003) indicating both were
species estabfrshed west
in
cenfral Florida prior to 2000. Lockhart (Statewide Lygodium
treatment
site
evaluation project. Florida Natural Areas Inventory, Tallahassee, FL. Available
on
http://www.friai.org/pdf/Lygodium_Report_2007.pdf.
at: 2007) reported
that
both japonicum and microphyllum Avon
L. L. occurred Park Bombing Range
at
and Kissimmee
along the River Floodplain Polk County. Both
in species were
observed growing
also together along a disturbed mesic hydric ecotone
in
/
and Palm Beach
Sarasota Counties in south Florida (Lockhart,
2007).
Nauman
and Austin (Amer. Fern 68:65-66. 1978) reported japonicum and
L.
J.
microphyllum were both
well-established
L. in different parts of Florida and
two would
suggested the species meet
in cenfral Florida.
Historically,
L.
common
japonicum was most
north of Orlando with records
as far south
as
CoUier County, while microphyllum was most common
south
L. of the northern
Lake Okeechobee with
section of scattered populations Polk County
into
to the
north (Pemberton and Herbarium
Ferriter, 1998). records accessed on
the
from
internet the University of Florida (FLAS,
2008), Florida State University
(FSU, 2008), University of South Florida (Wunderlin and Hansen, and
2008)
Fairchild Tropical Gardens (FTG, 2008) dating from 1930-2008
indicate
that
=
70% documented
(n 190) of occurrences of L. japonicum occur north
of
AMERICAN FERN JOURNAL: VOLUME NUMBER
100
(2010)
1
FLAS
P5939
FLAS
P207
FLAS
P3270
=
Orlando (N 28 25'-WGS 84 Datum) while 98% documented
(n 91) of
occurrences of L. microphyllum occur south of Orlando. Pemberton (Sida
new
20:1761-1761. 2003) reported a population of microphyllum in east
L.
Orlando that increased the northern distribution by 70 km, an indication that the
two species ranges have over-lapped further north than reported by Myers and
A
Wunderlin
2005 herbarium record from Volusia County, Florida
(2003).
km
indicated that microphyllum occurred 90 north of Orlando (USF
L. ca.
km NE
#540261). This population microphyllum was
of L. located ca. 3.5 of
Ormond km
Beach and Daytona
13.0 north of Beach.
ca.
Of known
the five earliest herbarium records of japonicum in Florida, four
L.
of these records are from locations south of Orlando, two of which are from the
southern end of the peninsula in Dade and Collier County (Table However,
1).
japonicum
L. has not spread across the landscape of south and central Florida
to a similar extent as L. microphyllum and more invasive in north Florida.
is
Twenty-one
percent of the herbarium records japonicum occur south
for L. that
of Orlando are from areas in Hillsborough, Manatee and Polk
Pinellas,
Counties indicating that japonicum has long been established in west-
L.
=
Only 3.7% documented japonicum
central Florida. (n of records for
7) L.
occur in Dade and Collier Counties in the southern peninsula of Florida.
combined
In 2005, the coverage of both species of Lygodium based on aerial
was
surveys estimated to be 74,122 ha in the central and south regions of Florida,
with 48,898 ha in the southern region, most of which was likely microphyllum
L.
and Pemas, Wildland Weeds
(Ferriter 9(2):7-9. 2006). During floral surveys of
Water Conservation Areas and no
2 3 in the central Everglades, reports of
Lygodium were documented
spp. in the late 1950's (Loveless, Ecology 40:1-9.
common many
but presently microphyllum on
1959), L. tree islands in the
is
central and northern Everglades. There are no known documented reports on the
area coverage of L. japonicum and area coverage in the central and northern
its
Florida regions is unclear. Based on CIS analysis (Google Earth, http://earth.
google.com. 2008) of Lygodium spp. in Florida from documented and undocu-
SHORTER NOTES
mented km
microphyllum
records, L. currently ranges 430
ca. in latitude (north
to
km
south) in peninsula Florida, while japonicum ranges 550
L. ca. in longitude
(east to west) along the panhandle and northern and km
Florida, 570
ca. in
latitude (north to south) along the peninsula. Based on herbarium
records,
this
range expansion Lygodium <
of both
spp. in Florida has occurred 80
in
years.
Expansion
japonicum
of Hkely due
L. is to cultivation and propagule
dispersal throughout the state from multiple introductions. The expansion
of
microphyllum
due
L. is likely to accidental introduction. The known
earliest
herbarium
records of japonicum was known
L. indicate from
first
it
cultivation, while the earliest records of microphyllum was
L. indicate
it
present two
in nurseries. has been reported that microphyllum was used
It L. as
an ornamental (Gordon and Thomas,
in D. Simberloff, D. Schmitz and
C. T. C.
Brown,
Strangers
in Paradise. Island Washington, The
Press, D. C. 1997).
introductions two many
of these climbing
well
ferns, as as other non-native
plants, indicates the need screening and new
for better evaluation
of plant
introductions into Florida (Gordon, Gordon
1998;
et ah, Invas. Plant
Sci.
Mange.
1:178-195.
2008).
New
sympatric records.—From we
2006-08,
observed four
locations in
which
both Lygodium
species occurred concurrently (Table At
three
2). sites
(Lakeland, Clermont, and was
Balm),
there
a distinct habitat delineation
between the two Lygodium japonicum was
species.
present at slightly higher
elevations in a soil mixture of sand/humus, while microphyllum was
L.
present lower humus
elevations
at in soils. Elevation differences where
at sites
japonicum and <
microphyllum
L. occurred were
L. together m.
1.0 Soils
where
japonicum was
L. present were more xeric to mesic, while where
soils
L.
microphyllum were were more
present mesic
to hydric. In addition,
L.
japonicum was
observed more open
in were exposed
sites that sunlight
to
while microphyllum was >
L. observed in more shaded with 50% canopy
sites
At Naples we
cover. the observed both growing
site, species together
in a
>99%
cypress strand, with microphyllum accounting Canopy
L. for cover.
>75%
cover the Naples was may
at site indicating that sunlight be
a factor in
the distribution of these two
ferns in Florida.
At Archbold
Biological Station in Highlands County, one author
(JTH)
observed a small area (< m^) of japonicum growing
1 L. in association with
multiple areas of L. microphyllum (> 50 m^). This sympatric population
swamp
occurred at the edge of a bay with a distinct delineation between
the
AMERICAN FERN VOLUME NUMBER
JOURNAL:
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two Lygodium japonicum
ferns. occurred in a mesic site while L. micro-
phyllum occurred in a hydric site on the edge of a bay swamp. The area
coverage of both species was relatively small and neither was growing into the
canopy, indicating they might have been recent
arrivals.
In 2002, a herbarium record (USF #235222) was submitted for japonicum
L.
common
Lucie County, where microphyllum
in along roadside canals
St. L. is
(Morgan and Overholt, Castanea 70:59-62. 2005). There are herbarium records
of L. japonicum from five counties in the southern one-third of peninsula
Florida including Lucie, Martin, Palm Beach, Dade and Discon-
St. Collier.
may
nected records for japonicum between southeast and southwest Florida
L.
humus
be due to low topography and soils of the Everglades region or a lack of
herbarium submissions. However, both microphyllum and
clear that
it is L. L.
japonicum more
are occurring together frequently in habitats of the central
Florida
region.
why
In south Florida, unclear microphyllum has spread so rapidly but
is L.
it
japonicum remains minor component south
L. still a floral in all habitats of
One
Florida. hypothesis for the differences in expansion is that L.
humus
microphyllum thrives in south Florida due to lower topography, soils
and
longer hydrological periods (Volin et Divers. Distrib. 10:439-446.
al.,
while japonicum due
2004), L. exists in northern Florida to higher topography,
more mesic soils and shorter hydrological periods. Hydric conditions and
humus may
soils prevent the establishment of japonicum gametophytes and
L.
may
sporophytes, while drier conditions and sandy prevent the
soils
A
establishment of microphyllum gametophytes and sporophytes. second
L.
may
hypothesis be temperature differences between north and south Florida.
A
third hypothesis is that L. japonicum is less competitive with native plants
than L. microphyllum. All of these hypotheses are likely interrelated, but
it
japonicum
appears that L. has failed to establish in high density in south
humus
due more and
Florida hydric conditions
to
soils.
peninsula Florida, possible that hybrids between japonicum and
it is L. L.
microphyllum could be produced. they do hybridize, there the potential
If is
for heterosis occur (Hoshizaki and Moran, Fern Growers Manual. Timber
to.
A
Press, Portland, OR. 2001; Moran, Natural History of Ferns. Timber Press,
Portland, OR. 2004) and further invasion of Florida by the hybrid. While
Knoblock (Taxon 33:256-270. reported review
et 1984) in a literature of fern
al.
were no Lygodium and
hybrids that there hybrids speciation in ferns by
hybridization appears to be a rare event (Tryon, Bot. Rev. 52:117-156. 1986).
Gomez
(Brenesia 18:155-170. 1980) reported that hybrids are frequent within
mixed populations Lygodium For example, two
of species. species of
Lygodium were reported hybridize forming Lygodium micans x venustum
to
in Trinidad that occur along different environmental gradients based on
pinnae length {Fay, Amer. Fern 63:165. 1973; Jermy and Walker, Bulletin of
J.
Museum,
the British Botany 13:251-276. 1985). In Trinidad, these two species
common commonly
with micans Sturm most found
are L. J.W. in forest
Gomez
and venustum Sw. found open
habitats L. is in sites. (1980) reports on
SHORTER NOTES
an
additional hybrid Lygodium
of spp. {Lygodium x
lancetillanum]
as a cross
between
heterodoxum Kunze and
L. ventustum. seems
L. Clearly, there be
to
potential for hybridization between japonicum and microphyllum which
L.
L.
could
affect future distributions of these species
in Florida.
Additional
distribution records.—During October we documented
2008,
L.
japonicum
growing
in the interior of a cypress strand in Naples, Florida (N 26°
W
12' 081= <
47.7", 45'
was
52.2"). Infestation of the fern 0.05 ha but
at least
We
five distinct populations were observed
at the observed japonicum
site.
L.
growing
at the base of bald cypress [Taxodium distichum
(L.) Rich.l to heights
of m, where ground was
2.5 cover dominated by
microphyllum and
L. the
>
height of microphyllum was
L. than m.
15.0 Native plants found
in
association both Lygodium
species of Naples included
at bald
cypress,
groundsel
tree {Baccharis wax
halimifolia myrtle
[Myrica
L.),
cerifera
(L.)
Small], myrsine [Rapanea punctata
(Lam.) Lundell], slash pine [Pinus
elliottii
Engelm. plum
var. coco [Chrysobalanus swamp
elliottii), icaco
L.), fern
[Blechnum
serrulatum [Osmunda
Rich.), royal fern and
muscadine
regalis
L.),
Two
{Vitis rotundifolia Michx.). non-native were
species found
also with
the
and
fern included: creeping oxeye
[Wedelia
and
trilobata Pruski]
(L.) Brazilian
pepper
[Schinus
The
terebinthifolius Raddi).
interior portion of the was
site
undisturbed was
relatively but surrounded by development on
sides
all
suggesting that hydrological and
nutrient alterations have occurred. The
site
was
dry at the time of the survey, but some moisture was
soil present. seems
It
unlikely japonicum was
that planted
L. at this site, but invaded as spores from
unknown
an
source. This species has been County
in Collier since the
1930's.
we
December
documented
In 2008, new, unknown
a previously
location of
W
microphyllum
L. in Lake County, Florida (N 28° 56' 40.9", 081= 43'
03.5").
This population microphyllum km
of L. represents an 40
range
ca. increase
to
the north from the population reported by Pemberton
along
(2003) the
central
km
and
ridge of Florida, 45 south
is ca. of a population microphyllum
of
L.
documented
along
the east coast of Volusia County during February
2005
(Wunderlin and Hansen, 2008; Accession # The
240261). was
infestation
ca.
ha
0.05 in size along floodplain habitat at Lake Holly. The fern occurred from
m
the edge of the lake inward about 25-30
to of the floodplain. The
highest
m
and
density cover
of the fern occurred from
ca. 5 the lakes edge, but
scattered populations were found to the north, east and south. The was
fern
m
growing up
to 4.5 in height, equaling the height of the native
tallest plants,
and pinnae were Some 10%
fertile present. necrosis was
(ca. total foliage)
due
observed to recent freezes. Native plants associated with
the fern Lake
at
Holly included coastalplain willow
[Salix caroliniana
Michx.), sawgrass
[Cladium jamaicense swamp wax
Crantz), royal fern, myrtle and duck
fern,
The
potato [Sagittaria latifolia Willd.). non-native species, Peruvian prim-
rosewillow [Ludwigia peruviana (L.) H. Hara], was also present. This new
record
may
along the central ridge of Florida be an
indication microphyllum
that
L. will
become
problematic in the lakes region of north
central Florida.
extreme
In the southeast part of peninsula Florida, undocumented
records
of
W
km
L. microphyllum occur ca. 3.5 west (N 25 26' 01.1", 080 22'
00.7") of
AMERICAN FERN VOLUME NUMBER
JOURNAL:
100
(2010)
1
Turkey Point Nuclear Power Plant in Florida City south of Miami. At this site
the fern was well established, growing into Australian pine [Casuarina
m
>
equisetifolia L.) to heights 10 and along the edges of mangroves. This
km
population occurs 8 southeast of Homestead, suggesting that
ca. L.
hammocks Key which
microphyllum could invade tropical in Largo, are
km
According manager 2006
located ca. 16 to the south. to the site in (Geoff
West, Florida Power and Lights, pers. comm.), microphyllum occurs several
L.
km
south of this site along Card Sound Road. As suggested by Goolsby (Nat.
Areas 24:351-353. 2004), climates in Caribbean, Central and pats of South
J.
America are suitable for microphyllum, as well as habitats throughout the
L.
Florida Keys.
—
Herbarium
Potential distribution in Florida. records indicate that L.
japonicum well established throughout Florida, but most invasive in
is is
>76
the northern part of Florida. After years presence in Florida,
it is
unknown
japonicum become wetland
L. will as great a threat to ecotones,
if
swamps, and
forested Everglades trees islands in southern Florida that L.
microphyllum has become. However, the lag time before some non-native
plants become invasive can be 70-100 years (Hobbs and Humphries, Conserv.
Biol. 9:761-770. 1995). in the central Florida region from Ocala (N 29= 07')
It is
where japonicum and microphyllum
to Sebring (N 27 28') L. L. are likely to
'
two
occur together out-competing native vegetation in natural areas. the
If
ferns become dominant in the same natural habitat, unclear control
it is if
become more The Nature
efforts herbicides, biocontrol) will difficult.
(e.g.,
Lygodium work
Conservancy's Central Florida Strategy (CFLS) designed to
is
with both private and public landowners in a 12 county region in central
and
Florida region to stop the spread of japonicum into south Florida L.
L.
microphyllum into north Florida (Higgins ah, Nat. Areas 27:236-250.
et
J.
2007; TNC, The Nature Conservancy stopping the spread in central Florida
-
(http://www.nature.org/wherewework/northamerica/states/florida/science/
CFLS
The and
art23406.html). 2009). goal of the early detection rapid
is
Lygodium
response to treat spp. within the 12 county region.
Goolsby (2004) suggested that defoliation of L. microphyllum and its
may
grow
during periods cold temperatures
inability of limit
to its
competitiveness with native plants, limiting range to areas south of
its
We
microphyllum behave japonicum
Orlando. hypothesize that will like
L. L.
during freezes and then re-sprout vigorously in northern Florida during the
The growing season 270 days northern Florida compared with
spring. in
is
330 days along the southeast and southwest coasts of Florida (Henry et al. The
and
Climate Weather of Florida. Pineapple Press, Inc., Sarasota, FL. 1994). is
It
now
microphyllum has invaded between Lake and Volusia
likely that areas
L.
Counties to the northeast, though no herbarium records currently exists. This
where
area includes the Johns River basin surface air temperatures are
St.
How
warmer microphyllum
than the surrounding successfully
slightly area. L.
invades and establishes north of Orlando unknown, but measures should
is all
be attempted to stop spread into north-central Florida. Stopping the spread
its
of L. microphyllum into south Florida rocklands including the Florida Keys is
SHORTER NOTES
50
1940's
)'s 1950's 1960's 1970's 1980's 1990's 2000's
Decade
Number
Fig. 1. of herbarium records per decade from UF (FLAS), FSU, USF (Wunderlin and
equally important because has numerous endemic The
this habitat
plants. lack
and humus may
of freshwater
soils limit the spread of microphyllum
in the
L.
Florida Keys.
USDA
microphyllum
It is clear that L. has spread into Cold Hardiness Zone 9A
minimum
where -6 -3
in Florida the average temperature can range between
to
C. North Florida receives 4-9 days in December and 5-11 days in January in
which
the temperatures drops below 0 "C, while south Florida only receives 0-
days both December and which
1 in January in the temperatures drops below
0
C
(Henry
et al, 1994). Potentially, L. microphyllum could spread along the
southeast coast of Florida northward
to the Jacksonville/Georgia border, north
along the central ridge to Ocala, and along the west
coast of Florida
to the
northern edge County
of Citrus or southern Levy County. This
the
potential
is
northern range of microphyllum suggested by Pemberton and
L. Goolsby
(2003)
we
(2004). In lab experiments, observed young sporophytes of microphyllum
L.
C
resprout three hours -2.2 and
after at spore germination following 12 hours
at
C
-2.2 (Hutchinson and
Langeland, unpubl.
data).
Conclusions.—Based on herbarium USF
records (FLAS, FSU, and
FTG),
were
there increased japonicum
reports of L. during the 1960's and
L.
microphyllum
in the 1990's Considering japonicum was
(Fig. that
L.
1). first
documented
in Florida ca. 1930, appears that within 30 years of being
it
—
AMERICAN FERN VOLUME NUMBER
JOURNAL:
100
(2010)
1
documented had began spread across the possibly from multiple
to state,
it
introductions and increased propagule pressure. Yet, japonicum has failed
L.
We
at this point in time to establish and invade natural areas of south Florida.
observed a similar invasive pattern based on herbarium records of
L.
microphyllum, herbarium were documented
in v\fhich increased records
ca.
was unknown
30 years after reported in Florida. However,
it first it is if L.
microphyllum was introduced more than two was
into sites in Florida.
It
reported that microphyllum was sold Royal Palm Nursery in Manatee
L. at
County from 1888-1930, but evidence from a photo in the nurseries catalogue
and was japonicum
a description of hardiness indicates (Pemberton
its it L.
and
Ferriter, 1998).
Based on our observations and those Lockhart coverage
of of
(2007), L.
microphyllum dominates japonicum where
L. in sites these species are
Based on two
sympatric. limited observations in Florida, these species can
occur in close proximity, but are separated by distinct ecotones based on slight
changes (< m) There evidence introduced and
1.0 in elevation. that species
is
new may
habitat disturbance within a range create ideal situations for
and
hybridization possibly heterosis in ferns (Walker, Evolution 12:82-92.
1958; Fay, 1973; Gomez, 1980; Kentner and Mesler, Am. Bot. 87:1168-1174.
J.
numerous and two
2000). Habitat disturbances are in Florida invasive
now
climbing ferns are present in close proximity. Both japonicum and
L. L.
microphyllum high up 100%) from hard
foliage exhibit necrosis (i.e., to frosts,
but re-sprouting occurs from rhizomes below the indicating these species
soil,
<
may
can temperatures Lygodium microphyllum
tolerate O'C. exhibit the
same tolerances as L. japonicum with regard to temperature, while invading
further into north Florida. remains unclear japonicum will invade
if L.
It
natural areas of southern Florida, but with multiple introductions throughout
and by
the state the potential for long distance dispersal spores, possible
it is
may
that this species increase at an exponential rate. Jeffrey T. Hutchinson
and Kenneth A. Langeland, University of Florida, Agronomy Department,
NW
and
Center Aquatic 7922 71^*
for Invasive Plants, Street, Gainesville,
Florida, U.S.A.
lobbiana—
Carbon Isotope (8"C) Signatures of Rheophytic Dipteris As with
show
most plant groups, ferns their highest diversity in the tropics (Mutke and
Moore
Barthlott, Biol. Skr. 55:521-537. 2005). Dipteris lobbiana (Hook. a
is
/.)
commonly
fern species found growing in riparian habitats throughout the
Borneo where and
tropical island of often strongly attached to rocks along
is
it
which
within streams belongs the family Dipteridaceae has two
(Fig. to
1). It
genera and nine species found only in the Palaeotropics (Kramer, in K. U.
Kramer & Green The Families and Genera Vascular Plants
P. S. eds. of Vol.
1.
and Gymnosperms:
Pteridophytes 99-101. Springer- Verlag, Berlin, Germany.
1990).