Lemna valdiviana
A tiny native Florida duckweed now identified as Valdivia Duckweed, this species has been introduced to the Freshwater Lake multiple times; its history is one of rapid consumption and repeated failed establishment in a nitrogen-limited closed system where grazers have consistently outpaced its growth.
Introduced to the Freshwater Lake multiple times over the history of miniBIOTA and identified as Lemna valdiviana, this small free-floating plant has repeatedly failed to establish. The last known surviving duckweed remained on the glass above the waterline and was identified as Valdivia Duckweed in September. On October 10, 2026, Josue reported that it had lost nearly all its color, judged it dead without a prospect of further budding or recovery, and recorded the species as extirpated. The actual death date and cause remain unknown.
Lemna valdiviana is a small free-floating aquatic monocot native to the Americas, with a range extending from the United States (including Florida) through Central and South America. Named after Valdivia, Chile, where it was first described, it is one of several Lemna species found in Florida's warm freshwater habitats: ponds, ditches, marshes, slow-moving rivers, and lake margins.
Each frond is 2 to 4 millimeters across, slightly elongated and asymmetrical compared to the rounder fronds of Lemna minor, with a single trailing rootlet. As with all Lemna species, reproduction occurs primarily through clonal vegetative budding: new fronds bud directly from the parent frond, separate, and form independent plants. Under optimal conditions of warm temperature, adequate light, and sufficient dissolved nitrogen, a population can double in two to four days.
Growth rate is strongly dependent on dissolved nitrogen availability. In nutrient-poor or cool systems, budding slows dramatically, and introduced biomass is typically consumed by grazers before the population can expand. This is the documented failure mechanism of prior Valdivia Duckweed introductions in miniBIOTA: the Freshwater Lake's nutrient limitation prevented the rapid budding needed to outpace grazing.
In the Freshwater Lake, Valdivia Duckweed's potential ecological functions include primary production at the water surface, dissolved nitrogen and phosphorus uptake, surface shading to suppress phytoplankton and suspended algae, and food provision as high-protein floating plant biomass for invertebrate consumers.
Prior introduction attempts have not resulted in stable population establishment, due to a documented cycle of nutrient limitation slowing growth while grazers consume introduced biomass faster than it can expand. The June 30, 2026 reintroduction occurred under changed conditions: no fish were present to graze the plants, and the motivation is to evaluate floating plants as a nutrient management tool against persistent green water. On July 1, 2026, Slough Crayfish were confirmed climbing to the surface and feeding on the duckweed and other floating plants from below, one day after introduction, indicating that invertebrate grazing pressure remains a factor even without fish present.
### October 10, 2026 extirpation assessment
The remaining duckweed material was still on the glass but had lost nearly all its color. Josue judged the last known survivors dead, with no expected recovery or new budding, and the species is now considered extirpated. This is the date of the assessment, not a known death date; viability was not independently tested and the cause of the final loss was not established.
### September 10, 2026 observation
Josue identifies surviving Valdivia Duckweed on wet glass above the Freshwater Lake waterline, out of crayfish reach. This establishes positive presence, not establishment or the identity of every historical fragment.
Introduction context: Valdivia Duckweed has been introduced to the Freshwater Lake multiple times. The most recent prior introduction was a wild-collected sample on April 8, 2026, framed at the time as a temporary disruption rather than a stable solution. On June 30, 2026, the species was reintroduced alongside three other floating plant species (Lesser Duckweed, Dotted Duckweed, and Water Spangles) as a final evaluation of floating vegetation's ability to shift nutrient dynamics in the lake.
Valdivia Duckweed has been introduced to the Freshwater Lake multiple times. All prior attempts failed due to nutrient limitation: miniBIOTA's dissolved nitrogen is insufficient to sustain rapid budding, and introduced biomass was consumed before population expansion could occur. Most recent prior introduction: wild-collected April 8, 2026, outcome unresolved. Reintroduced June 30, 2026 alongside three other floating plant species as a final evaluation of floating vegetation's ability to shift nutrient dynamics in response to persistent green water. No fish were present. On July 1, 2026, Slough Crayfish were confirmed feeding on the floating mat from below, one day after reintroduction. By July 30, 2026, the trial had been reduced to approximately 98% cover loss; predation, excessive light intensity, and possible low surface airflow are all proposed as contributing factors, none confirmed or ranked. By August 3, 2026, only a tiny duckweed fragment (species undistinguished, out of crayfish reach) and a couple of Water Spangles remained across the whole trial. Josue identified surviving Valdivia Duckweed on wet glass above the waterline September 10, 2026. On October 10, 2026, he reported near-total color loss in the remaining glass material, judged it dead without recovery or new budding, and the species is now considered extirpated. This is Josue's assessment without independent viability testing; the actual death date and cause remain unknown. The last living duckweed was seen September 10, 2026; its colorless remnants were last observed October 10, 2026.
Primary Producer. Fixes light energy into floating plant biomass through photosynthesis; absorbs dissolved nitrogen and phosphorus from the water column during growth. In miniBIOTA, the target functions are primary production at the surface and nutrient uptake to reduce phytoplankton-sustaining dissolved nutrients. Growth rate depends entirely on nutrient availability; repeated failures reflect the system's nitrogen limitation rather than any deficiency in the plant's biology.
Freshwater floating plant native to the Americas including Florida. Requires calm or slow-moving water and adequate dissolved nitrogen to sustain rapid growth. Sensitive to nutrient limitation; in low-nitrogen systems growth stalls and introduced biomass is consumed before surface coverage develops. Florida-native; tolerates warm subtropical temperatures.
Primary production and aquatic habitat structure
Follow this species across the habitats where it currently appears in the miniBIOTA biosphere.
This chronicle is connected here as related context. Open the primary chronicle for the full story.
Duckweed and Water Spangles were added as a floating-plant challenge to the Creeping Primrose Willow, but crayfish consumed them and the willow grew upward...
Duckweed remains freshwater floating-plant comparison context.
