We tested whether the presence of a second species influenced the growth rate of the three duckweed species Lemna minor, Lemna gibba, and Lemna turionifera. We used four different Zn concentrations in a replicated microcosm experiment under sterile conditions, either growing the species in isolation or in a 2-species mixture. The cultures were kept in an incubator 20 °C with a light regime of 16/8h light/dark for 17 days.

There is one data set with the number of fronds (individuals) counted over 8 times over a period of 17 days. The metadata is contained in the data file. 

There were six different compositions (three isolated, three mixed), four Zn concentration levels, and every treatment was replicated three times, thus in total, there were 72 cultures. 

The number of fronds were counted 8 times over the course of 17 days. Completely white (dead) fronds were not included in the total number of fronds. During the experiment, the species got mixed in a small number of bottles. Due to their morphological similarity, the species could not be reliably distinguished anymore and consequently any data from these bottles post the mixing event were excluded from the data analyses (listed as "NA" in the data file).

The data was collected in 2021.