The reproductive biology of the invasive ferns Lygodium microphyllum and L. japonicum (Schizaeaceae): implications for invasive potential

Abstract

The effect of culture system and population source on sexual expression and sporophyte production was examined for two invasive fern species in Florida, USA, Lygodium microphyllum and L. japonicum (Schizaeaceae). Both species are currently spreading through Florida. Long-distance dispersal of ferns is thought to rely on successful intragametophytic selfing. Given the rate of spread observed in both Lygodium species, we hypothesized that both species are capable of intragametophytic selfing. To test this hypothesis, gametophytes of both species were grown in vitro as isolates, pairs, and groups. Both species were capable of intragametophytic selfing; 78% of L. microphyllum isolates produced sporophytes and over 90% of the L. japonicum isolates produced sporophytes. Lygodium microphyllum also displayed the ability to reproduce via intergametophytic crossing, facilitated by an antheridiogen pheromone. Sporophyte production was rapid across mating systems for both species, an advantage in Florida's wet and dry seasonal cycles. The high intragametophytic selfing rate achieved by both species has likely facilitated their ability to colonize and spread through Florida. The mixed mating system observed in L. microphyllum appears to give this species the ability to invade distant habitats and then adapt to local conditions.

Morpho-anatomical description of Lygodium hazaricum Haq a new contribution to the fern flora of Pakistan

“…2F). Lott et al (2003) also reported the reproductive biology of Lygodium microphyllum (Cav.) R. Br.…”

“…Previously it was placed in family Schizaeceae (Murtaza et al 2004). The plants of Lygodiaceae family are terrestrial (Lott et al 2003). Stems slender; branched, fronds several meters, alternately pinnate, climbing by means of a twining rachis; primary blade divisions (pinnae) pseudo dichotomously forking with a dormant apical bud in axils; pinnules entire to palmately or 1-or 2-pinnate or more divided; fertile and sterile pinnae similar or fertile pinnae greatly contracted; veins free or anastomosing; sori on lobes of ultimate segments; sporangia abaxial, solitary, 1 per sorus, each sporangium covered by an antrorse indusium-like subtending flange; spores 128-256 per sporangium, tetrahedral and trilete; gametophytes green, cordate, terrestrial.…”

Biology and Reproductive Parameters of the Brown Lygodium Moth, <I>Neomusotima conspurcatalis</I> - A New Biological Control Agent of Old World Climbing Fern in Florida

“…This aggressive indeterminate vine can climb 20 m or more into trees and can extend horizontally, smothering native vegetation and reducing plant diversity and ecosystem services (Gordon 1998;Pemberton & Ferriter 1998). Lygodium microphyllum produces vast numbers of spores that are windborne and opportunistically selfcompatible (Lott et al 2003;Volin et al 2004).…”

Influence of Soil Biogeochemical Properties on the Invasiveness of Old World Climbing Fern (Lygodium microphyllum)

“…Lygodium microphyllum spreads quickly in the South Florida's landscape because of its ability to reproduce through the three mating systems possible in a fern: intra-and intergametophytic selfing and out-crossing (Lott et al, 2003). Spores can germinate in six to seven days (Brown, 1984).…”

“…Managing L. microphyllum has been a significant challenge for land resource managers and researchers because of its extensive rapid invasion in natural areas of south Florida. Much of the research work previously performed on L. microphyllum focuses on reproductive potential, spore release, belowground rhizome dormancy and survival strategies investigating its invasiveness (Lott et al 2003). Read (1991) stated that the mycorrhizal association is the most ubiquitous and abundant form of terrestrial symbiosis, and AMF are considered the most common type of mycorrhizae which dominates grasslands, croplands, tropical forests, and desert communities.…”