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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #435243
Research Project: Development and Implementation of Biological Control Programs for Natural Area Weeds in the Southeastern United States

Location: Invasive Plant Research Laboratory

Title: Examination of the reproductive ecology of Pistia stratiotes L. in Florida

Author
item ZITELLI, ANGELINA - Florida Atlantic University
item FRAZIER, EVELYN - Florida Atlantic University
item Dray Jr, Forrest

Submitted to: Society of Wetland Scientists
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Waterlettuce is a floating aquatic weed whose ecology is poorly understood. Recently USDA scientists discovered that there are multiple genotypes and possibly even multiple cryptic species within this genus, which makes understanding ecological differences between the genetic types even more important given the need for management. This poster compares the reproductive ecology between an invasive genotype and native genotype of waterlettuce in Florida. Preliminary analysis suggests the native genotype produces fewer seeds than the invasive and during slightly different times of the year. There also appears to be at least one native genotype that is sterile. Pollination studies are ongoing.

Technical Abstract: Pistia stratiotes (waterlettuce) is one of the world's most problematic aquatic weeds, yet its reproductive ecology remains poorly understood. While vegetative propagation via stolons is documented, sexual reproduction, pollination mode, and floral microbiome contributions to population dynamics have received little attention. This knowledge gap limits management strategy effectiveness. This study investigates reproductive phenology, pollination mechanisms, and floral microbiome composition in two Florida haplotypes: "Type A" (invasive) and "Type E" (native). Preliminary seed production studies compared Type A (n=10) and Type E (n=15) plants over 18 months in mesocosms. Pollination experiments exposed 100 tagged plants (50 per haplotype) to five treatments: open pollination, pollinator exclusion, manual self and cross pollination, and emasculated control. Seed set was quantified 14 to 21 days post anthesis. Pollinator identity was assessed using Tangle Trap adhesive on spathes. Floral microbiome composition was characterized via culture based methods. Reproductive phenology peaked Feb to May, with Type A producing more fruits and seeds per fruit than Type E. Winter showed low reproduction, indicating pollen limitation under natural conditions. Pollinator visitation appeared dominated by small arthropods, consistent with P. stratiotes' reliance on vegetative reproduction. Culture based microbiome screening revealed no difference in microbial assemblages between haplotypes, suggesting environmental conditions drive floral microbial composition. Sexual reproduction in P. stratiotes is functionally present but pollinator limited. Understanding these dynamics offers novel strategies for reducing waterlettuce spread and protecting native freshwater biodiversity.