First report of foliar nectar production by Lygodium microphyllum (Lygodiaceae), an invasive fern in Florida

Authors: SEBESTA, NICOLE - Florida International University; Jones, Ian; Lake, Ellen

Submitted to: American Fern Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2018
Publication Date: 12/21/2018
Citation: Sebesta, N., Jones, I.M., Lake, E.C. 2018. First report of foliar nectar production by Lygodium microphyllum (Lygodiaceae), an invasive fern in Florida. American Fern Journal. 108(4):180-183. https://doi.org/10.1640/0002-8444-108.4.180.
DOI: https://doi.org/10.1640/0002-8444-108.4.180

Interpretive Summary: Foliar nectar has been documented on 43 extant fern species belonging to nine genera in five families. We report the first observation of foliar nectar production by Old World climbing fern, Lygodium microphyllum, which is a member of a sixth family, Lygodiaceae. Lygodium microphyllum is native to tropical and subtropical areas of Asia, Africa and Australasia. First cultivated in the USA as an ornamental, the species has since become invasive in wet and mesic environments of south and central Florida. In May 2017 we observed small beads of nectar on the petiolule, pinnule-rachises and tertiary segments of several sterile and fertile pinnae of L. microphyllum plants in the greenhouse at Florida International University. Subsequent nectar collections were performed to determine the concentration of nectar. The average concentration found on mature sporophyte petiolules was 14.4% (n = 21, SE = 0.7). We review existing literature on the role of fern foliar nectar, and suggest that the nectar may play a defensive role. The observation of foliar nectar on L. microphyllum is of particular interest as it raises the question of whether the production of foliar nectar may contribute to the plant’s invasive status.

Technical Abstract: Foliar nectar has been documented on 43 extant fern species belonging to nine genera in five families. We report the first observation of foliar nectar production by Old World climbing fern, Lygodium microphyllum, which is a member of a sixth family, Lygodiaceae. Lygodium microphyllum is native to tropical and subtropical areas of Asia, Africa and Australasia. First cultivated in the USA as an ornamental, the species has since become invasive in wet and mesic environments of south and central Florida. In May 2017 we observed small beads of nectar on the petiolule, pinnule-rachises and tertiary segments of several sterile and fertile pinnae of L. microphyllum plants in the greenhouse at Florida International University. Subsequent nectar collections were performed to determine the concentration of nectar. The average concentration found on mature sporophyte petiolules was 14.4% (n = 21, SE = 0.7). We review existing literature on the role of fern foliar nectar, and suggest that the nectar may play a defensive role. The observation of foliar nectar on L. microphyllum is of particular interest as it raises the question of whether the production of foliar nectar may contribute to the plant’s invasive status.