Pilosocereus polygonus

Pilosocereus polygonus
Botanical illustration – the lectotype
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Cactaceae
Subfamily: Cactoideae
Genus: Pilosocereus
Species:
P. polygonus
Binomial name
Pilosocereus polygonus
(Lam.) Byles & G.D.Rowley
Synonyms[1]
List
  • Cactus polygonus Lam.
  • Cactus royenii L.
  • Cephalocereus monoclonos (DC.) Britton & Rose
  • Cephalocereus polygonus (Lam.) Britton & Rose
  • Cephalocereus royenii (L.) Britton & Rose
  • Cephalocereus schlumbergeri (F.A.C.Weber ex K.Schum.) Urb.
  • Cereus monoclonos DC.
  • Cereus polygonus (Lam.) DC.
  • Cereus royenii (L.) Mill.
  • Pilocereus monoclonos (DC.) F.M.Knuth
  • Pilocereus plumieri Lem.
  • Pilocereus polygonus (Lam.) Salm-Dyck
  • Pilocereus royenii (L.) Haw. ex Rümpler
  • Pilocereus schlumbergeri F.A.C.Weber ex K.Schum.
  • Pilosocereus monoclonos (DC.) Byles & G.D.Rowley
  • Pilosocereus royenii (L.) Byles & G.D.Rowley, tentatively listed as a synonym.

Pilosocereus polygonus is a species of cactus (family Cactaceae). Like all species in the genus Pilosocereus, it has a shrub- or tree-like growth habit. It has been treated very differently at times. In the narrow circumscription adopted here, it is endemic to Hispaniola, a position adopted by Britton and Rose in 1920 and endorsed in a 2019 review of the genus in the Caribbean and northern Andes. Treatments in the late 1990s and early 2000s used a much broader circumscription, which included species now recognized as separate, thus giving P. polygonus a much wider distribution.[2] As of July 2025, Plants of the World Online accepted Pilosocereus royenii as a synonym;[1] however it has also been treated as a separate species.[2] Broadly applied English names include dildo cactus,[3] pipe organ cactus,[4] and Royen's tree cactus.[5]

Description

When Pilosocereus polygonus is narrowly circumscribed, it is a species of cactus having green to gray-green stems with 8–13 ribs. Its branches are ascending, sometimes completely upright. The areoles have rigid spines up to 3 cm (1.2 in) long that are dull yellowish when new. Flowering areoles have dense tufts of silky hairs up to 3 cm (1.2 in) long. Non-flowering areoles have fewer hairs. The flowers are 5–7 cm (2.0–2.8 in) long, with reddish green outer segments (tepals) and white inner segments. The fruit is red.[2]

Taxonomy

Pilosocereus polygonus has a complicated taxonomic history. The species was first described by Jean-Baptiste Lamarck in 1785 as Cactus polygonus. It was transferred to the genus Pilocereus in 1845,[1] but this genus name is illegitimate, and was replaced by Pilosocereus in 1957.[6] In 1909, Britton and Rose placed the species in the genus Cephalocereus. In their 1920 treatment of this genus, Britton and Rose recognized 18 species in the Caribbean and northern Andes, one of which was Cephalocereus polygonus, which they regarded as endemic to Hispaniola. Many subsequent authors followed this approach when Cephalocereus was split and the relevant species placed in Pilosocereus. However, treatments in the late 1990s and early 2000s used many fewer species, often only three, with Pilosocereus polygonus given a very broad circumscription. A 2019 review of Pilosocereus in the Caribbean and northern Andes returned to a larger number of species with narrower circumscriptions. Pilosocereus polygonus was again regarded as endemic to Hispaniola.[2]

The relationship between P. polygonus and the name Pilosocereus royenii has also varied. In 2001, Anderson described them as separate species.[7] As of July 2025, Plants of the World Online regarded them as synonyms.[1] Populations in Mexico treated as P. royenii by some authors are considered to be P. gaumeri by others,[8] including Plants of the World Online as of July 2025.[9] A species found in Puerto Rico and the Virgin Islands that has been called P. royenii is now treated as Pilosocereus armatus.[10][11]

Subspecies

No subspecies were accepted by Plants of the World Online as of June 2025.[1] Those that have been proposed are treated as full species:

Conservation

Under the synonym Pilosocereus royenii, it was assessed in 2011 as "Least Concern", but with a very much wider distribution.[15]

References

  1. ^ a b c d e "Pilosocereus polygonus (Lam.) Byles & G.D. Rowley". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2025-06-03.
  2. ^ a b c d Franck, Alan R.; Barrios, Duniel; Campbell, Keron C. St. E.; Lange, James; Peguero, Brígido; Santiago-Valentín, Eugenio; Rigerszki, Zoltán; Haakonsson, Jane; Gann, George D.; Cinea, William; Howe, Natalie M. M.; St. John, James; Moreno, Juan Sebastián & Clark, Cynthia A. (2019). "Revision of Pilosocereus (Cactaceae) in the Caribbean and northern Andean region". Phytotaxa. 411 (3): 129–182. Bibcode:2019Phytx.411..129F. doi:10.11646/phytotaxa.411.3.1.
  3. ^ "Dildo Cactus, Providenciales, Turks & Caicis Islands, 30May-06June2002 - by David J. l'Hoste".
  4. ^ "Pilosocereus royenii". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 2009-12-04.
  5. ^ NRCS. "Pilosocereus royenii". PLANTS Database. United States Department of Agriculture (USDA). Retrieved 3 October 2015.
  6. ^ Byles, R.S. & Rowley, G.D. (1957). "Pilosocereus Byl. & Rowl. nom. gen. nov. (Cactaceae)". The Cactus and Succulent Journal of Great Britain. 19 (3): 66–67, 69. JSTOR 45475966.
  7. ^ Anderson, Edward F. (2001). The Cactus Family. Pentland, Oregon: Timber Press. ISBN 978-0-88192-498-5., pp. 585–587
  8. ^ Lavor, Pâmela; Versieux, Leonardo M. & Calvente, Alice (2020). "Phylogenetic Relationships of Pilosocereus (Cactaceae) and Taxonomic Implications". PlantNow. 1 (2): 52–70. doi:10.6084/m9.figshare.12895124.
  9. ^ a b "Pilosocereus gaumeri (Britton & Rose) Backeb." Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2025-07-26.
  10. ^ Korotkova, Nadja; Aquino, David; Arias, Salvador; Eggli, Urs; Franck, Alan; Gómez-Hinostrosa, Carlos; Guerrero, Pablo C.; Hernández, Héctor M.; Kohlbecker, Andreas; Köhler, Matias; Luther, Katja; Majure, Lucas C.; Müller, Andreas; Metzing, Detlev; Nyffeler, Reto; Sánchez, Daniel; Schlumpberger, Boris & Berendsohn, Walter G. (2021), "Cactaceae at Caryophyllales.org – a dynamic online species-level taxonomic backbone for the family", Willdenowia, 51 (2): 251–270, Bibcode:2021Willd..5151208K, doi:10.3372/wi.51.51208, p. 264
  11. ^ "Pilosocereus armatus (Otto ex Pfeiff.) A.R.Franck". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2025-07-26.
  12. ^ "Pilosocereus brevispinus Hoxey & Gdaniec". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2025-06-03.
  13. ^ "Pilosocereus curtisii (Otto) A.R.Franck". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2025-06-03.
  14. ^ "Pilosocereus jamaicensis Proctor". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2025-06-03.
  15. ^ Taylor, N.P. (2017) [amended version of 2013 assessment]. "Pilosocereus royenii". IUCN Red List of Threatened Species. 2017: e.T152164A121581463. doi:10.2305/IUCN.UK.2017-3.RLTS.T152164A121581463.en. Retrieved 30 November 2022.
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