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 JOURNAL: 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: 100 1 (2010) 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).