Pilosocereus armatus
Pilosocereus armatus is a species of flowering plant in the cactus family Cactaceae, native to the Virgin Islands and Puerto Rico. It was first described by Christoph Friedrich Otto in 1837 as Cereus armatus, and transferred to the genus Pilosocereus in 2021. It has been treated as Pilosocereus royenii, and Pilocereus royenii var. armatus is among its many synonyms. However, P. royenii is a name without a clear application.
Description
Pilosocereus armatus has bluish green stems with 7–11 ribs. Its branches are usually upright. Areoles have spines up to long and silky hairs up to long. Non-flowering areoles have fewer hairs. The flower is long. The inner perianth segments are pinkish, the outer ones pinkish to pale green. The fruit is red.
Taxonomy
There has been considerable confusion over the correct name for a species of the genus Pilosocereus found in Puerto Rico and the Virgin Islands. Sources have used Pilosocereus royenii, a name based on Linnaeus' Cactus royenii. However, the original description of C. royenii does not make clear its origin and precise identification. In 2019, an attempt was made to validate C. royenii by designating a neotype. This did not succeed because it did not take into account the earlier designation of a different neotype in 2013, which also failed to make clear its origin and precise identification. The earliest available basionym is Cereus armatus; hence as of 2025, the accepted name was Pilosocereus armatus.
Distribution
Pilosocereus armatus is native to Puerto Rico and the Virgin Islands.