This key is specifically developed for the identification of species belonging to the genus Pennisetum available on the European market. The reason for developing this key is the large number of Pennisetum species and varieties available and the difficulty of distinguishing them from each other. Since August 2017 one Pennisetum species, Pennisetum setaceum, is on the List of Invasive Alien Species of Union concern (the Union list), which forms the core of Regulation (EU) 1143/2014. Pennisetum setaceum being on the Union list entails that sales, distribution and cultivation of this species is prohibited. Furthermore, this entails that the species shall not be brought into the territory of the European Union, and the species shall not be released into the environment (Regulation (EU) 1143/2014).
The key includes descriptions and photos of 10 Pennisetum species and 27 Pennisetum varieties. Seventeen features can be scored in random order to find the right species. The features are illustrated with line drawings to facilitate identification.
For each species two separate entries are included, one based on measurements of herbarium specimens and one based on GrassBase, the Online World Grass Flora. Two separate entries are included because sometimes there are discrepancies between the two sources, especially concerning quantitative traits. Entries based on our own herbarium specimens better match plants in cultivation, while descriptions from GrassBase better correspond with plants in the wild.
To all entries of plant species and varieties two descriptions are attached. One is the Natural Language Description, which is an automatically generated description based on the feature scores that underlie the key. The second, entitled Extensive Description, is a manually created description, which gives more precise plant features and includes some additional information.
All entries are illustrated with photos, which is recommended to use as a final control step of the identification process. For most species also microscopic photos are included, detailing floral characteristics.
European Union. (2014). Regulation (EU) No 1143/2014 of the European Parliament and of the Council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species. Official Journal of the European Union, 57, 35.