Concern has been raised that in recent decades knowledge of plant species has severely declined in western countries. However, in the absence of regularly repeated and standardized surveys, no reliable statement can be made as to whether plant species knowledge has actually declined in recent decades. The present study aimed to contribute to filling this knowledge gap by repeating a survey on the knowledge of plant species twenty years later. Laypeople (all adults) were asked to identify 15 common wild plant species of Germany, which were presented to them as photographs. Based on previous research, five of the 15 species were considered well-known, five moderately known, and five rather unknown to laypeople. The original survey was conducted in 2002 at two locations in the city of Marburg, while its repetition took place in 2022/23, both in Marburg (identical location) and the city of Freiburg, as well as online. In total, 1558 individuals (18-88 years old) participated in the surveys. Participants identified, on average, 6.5 plant species correctly. Plant species knowledge did not decrease between 2002 and 2022/23, increased with age and the number of sources of plant species knowledge used, and was higher for women than men. The older the participants, the more likely they were to name gardening and other leisure activities as their sources of knowledge of plant species, and the less likely they were to name family and education. Although we did not find evidence for a decline in knowledge of plant species, the public showed a poor ability to identify plants (average identification of about 40 % of the species shown), indicating a disconnection from nature that may negatively affect society᾿s support for efforts to conserve biodiversity. Policy should thus aim to increase personal experience with plants from a young age to foster a better understanding of biodiversity.