Cenchrus setaceus (Forssk.) Morrone

Verloove, Filip, Gonçalves Silva, Juan J. & Leliaert, Frederik, 2024, Critical notes on grasses (Poaceae) of Madeira, Portugal, Phytotaxa 670 (1), pp. 1-17 : 12

Cenchrus setaceus (Forssk.) Morrone [syn.: Pennisetum setaceum (Forssk.) Chiov. ]

This species from North and East-Africa and southwestern Asia is one of the most invasive species in the Canary Islands ( González-Rodríguez et al. 2010) and its potential area even will increase under future climatic scenarios ( Da Re et al. 2020). Yet, in the island of Madeira, Cenchrus setaceus is a very recent newcomer: it was first found in 2018 and 2019, in Santa Cruz and Funchal ( Cabral et al. 2020). Soon afterwards, it was also recorded for the first time in Porto Santo ( Jardim & Menezes de Sequeira 2021). In Santa Cruz, the species was already abundant at the time of its discovery (+1000 individuals), whereas in Funchal a single specimen was found (and eradicated).

During our fieldwork in 2021 and 2022 the species’ presence and spread were confirmed. In Santa Cruz, C. setaceus has become very common, especially in the valley of the Ribeira de Santa Cruz, but also elsewhere in the area, e.g. near the airport. A new population with ca. 30 individuals was discovered in Funchal, along the Rua da Ribeira de João Gomes, below the VR-1 motorway. Scattered plants were also seen in Garajau, along the road that leads to the Garajau beach. Finally, a single individual was observed near the sea in Porto Novo (Gaula). From the above, it is obvious that the species is in the early stages of invasion and urgently needs to be removed by local authorities to prevent further harm.