Pilocereus

Pilocereus Lem., nom. illeg. (1839)

🌵 Author(s)	Charles Lemaire
🌵 Type	not cited

Etymology

Greek pilos ‘wool’ + Cereus, the name of a genus of columnar cacti and a designation for columnar cacti in general. For the cephalium, which Lemaire compared to a “wool cap”. Not from “Gr.” (actually Latin) pīleus ‘cap, hat’ (Boerner, Taschenwörterbuch der botanischen Pflanzennamen. 4. Auflage. 1989).

This genus originally included only Cereus senilis and Cereus columna-trajani. Lemaire suggested creating a separate genus for these two species in 1838, which Louis Pfeiffer did under the name Cephalocereus later that year. Lemaire, apparently unaware of this, published the name Pilocereus for the same two species the next year.

Pilocereus is therefore a later synonym of Cephalocereus. Karl Schumann (1899) tried to salvage the name by excluding the original two species, but this is not acceptable under the International Code of Nomenclature and a proposal to conserve Schumann’s Pilocereus over Lemaire’s was rejected in 1954. Three years later, Ronald Byles and Gordon Rowley published Pilosocereus as a replacement name for Pilocereus in the sense of Schumann.