Origin and Habitat: Yucatan Peninsula (Mexico), Bahamas, Dominican Republic, Puerto Rico Jamaica, Tobago, U.S. Virgin Islands, and Lesser Antilles.
Habitat: Pilosocereus royeniiSN|4681]]SN|4681]] is one of the most common cacti in the Caribbean that may be found scattered in most of the islands in dry sites from exposed beach benches to rocky cliffs, plains and hillsides and is often the most conspicuous cactus species. Other plants found in the same range comprise: Stenocereus hystrixSN|8036]]SN|8036]] amd Plumeria obtusa.
Ecology: Branches often have cavities about 5 cm in diameter, representing the predator-resistant nesting sites of small doves and other birds. Flower are pollinated by bats.

• Pilosocereus royenii (L.) Byles & G.D.Rowley
• Cactus royenii L.
• Cephalocereus royenii (L.) Britton & Rose
• Cereus royenii (L.) Mill.
• Pilocereus royenii (L.) Haw. ex Rümpler

• Pilosocereus royenii (L.) Byles & G.D.Rowley
• Cactus royenii L.
• Cephalocereus royenii (L.) Britton & Rose
• Cereus royenii (L.) Mill.
• Pilocereus royenii (L.) Haw. ex Rümpler
• Pilocereus strictus f. aureus (Salm-Dyck ex DC.) K.Schum.
• Cereus aureus Salm-Dyck ex DC.
• Pilosocereus barbadensis (Britton & Rose) Byles & G.D.Rowley
• Cephalocereus barbadensis Britton & Rose
• Cereus barbadensis (Britton & Rose) A.Berger
• Pilocereus barbadensis (Britton & Rose) A.Berger
• Pilosocereus brooksianus (Britton & Rose) Byles & G.D.Rowley
• Cephalocereus brooksianus Britton & Rose
• Cereus brooksianus (Britton & Rose) Vaupel
• Pilocereus brooksianus (Britton & Rose) F.M.Knuth in Backeb. & F.M.Knuth
• Pilosocereus curtisii (Salm-Dyck) Pfeiff.
• Cephalocereus nobilis var. curtisii (Salm-Dyck) Borg in Borg
• Cereus curtisii Otto
• Pilocereus curtisii Salm-Dyck
• Pilosocereus gaumeri (Britton & Rose) Backeb.
• Cephalocereus gaumeri Britton & Rose
• Cereus gaumeri (Britton & Rose) Backeb.
• Pilocereus gaumeri (Britton & Rose) F.M.Knuth in Backeb. & F.M.Knuth
• Pilosocereus haworthii (Spreng.)
• Cactus haworthii Spreng.
• Cereus haworthii DC.
• Pilocereus haworthii Console
• Pilosocereus millspaughii (Britton) Byles & G.D.Rowley
• Cephalocereus millspaughii Britton
• Cereus millspaughii (Britton) Vaupel
• Pilocereus millspaughii (Britton) F.M.Knuth in Backeb. & F.M.Knuth
• Pilosocereus monoclonos (DC.) Byles & G.D.Rowley
• Cephalocereus monoclonos (DC.) Britton & Rose
• Cereus monoclonos DC.
• Pilocereus monoclonos (DC.) F.M.Knuth in Backeb. & F.M.Knuth
• Pilosocereus nigricans (Lem.)
• Cephalocereus nobilis var. nigricans (Lem.) Borg
• Cereus nigricans Lem.
• Pilosocereus nobilis (Haw.) Byles & G.D.Rowley
• Cephalocereus nobilis Britton & Rose
• Cereus nobilis Haw.
• Pilocereus nobilis K.Schum.
• Pilocereus nobilis A.Berger
• Pseudopilocereus nobilis (Haw.) Buxb.
• Pilosocereus nobilis f. cristatus P.V.Heath
• Cephalocereus nobilis f. cristatus P.V.Heath
• Pilosocereus strictus (Wild)
• Cactus strictus Willd.
• Cephalocereus strictus Borg
• Cereus strictus DC.
• Pilocereus strictus (DC.) Rümpler
• Pilosocereus swartzii (Griseb.) Byles & G.D.Rowley
• Cephalocereus swartzii (Griseb.) Britton & Rose
• Cereus swartzii Griseb.
• Pilocereus swartzii K.Schum.
• Pilosocereus urbanianus (K.Schum.) Byles & G.D.Rowley
• Cephalocereus urbanianus (K.Schum.) Britton & Rose
• Cereus urbanianus (K.Schum.) A.Berger
• Pilocereus urbanianus K.Schum.

• Pilosocereus royenii f. cristatus (P.V.Heath)
• Cephalocereus royenii f. cristatus P.V.Heath

Description: Pilosocereus royeniiSN|4681]]SN|4681]] is an attractive blue-stemmed, tree-like cactus species. It is relatively large sized with tufts of whitish hairs near the branch ends, elongated flowers, and red-purple fruits. It is quite variable and has had at least 30 scientific synonyms.
Habit: Plants treelike, branching basally or above the ground, 2-8 m high, often with well-defined trunks. A 5 metres tall individual may be over 100 years old.
Roots: The root system is broad and near the surface to rapidly a absorb water from even the lightest rains.
Trunk: Up to 60 cm in diameter or larger, covered by a very thin, relatively smooth bark and reddish-brown.
Branches: Mostly vertical or sometimes ascending, stout, blue-green, (5-)7-9(-10) cm in diameter arising 30-60 above ground from a single trunk. Branches may branch again, and those yet again. The thick green skin on the branches carries out photosynthesis. Older basal parts of the branches often form a thick bark.
Ribs: 6-11 vertical.
Spines: Variable, white-grey, yellowish to reddish.
Central spines: 1-6, 32-60 mm long.
Radial spines: About 9, 19-26 mm long
Pseudocephalium: As Pilosocereus cacti age, they produce what is called a 'pseudocephalium', but in Pilosocereus royeniiSN|4681]]SN|4681]] the fertile portion is not well differentiated from normal vegetative parts. Flower-bearing areoles subapical and lateral, on one to three ribs, with long white hairs.
Flowers: Fleshy, whitish-green, rose pink or purple-red, to 5 cm long, 2,5-4 cm in diameter. They extend horizontallv out from the branches and open at night, but last into the next day.
Blooming season: Flowers are found year-round when rainfall is adequate .
Fruits: Depressed globose, pulp white or red. Fruits are edible, juicy and sweet and contain many tiny black seeds. Fruits do not have spines. They are usually found year-round.

Bibliography: Major references and further lectures
1) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/Aug./2011
2) David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006
3) Edward F. Anderson “The Cactus Family” Timber Press, 2001
4) M.M. Grandtner “Elsevier's Dictionary of Trees: Volume 1: North America, Volume 1” Elsevier, 08/apr/2005
5) T. Kent Kirk “Tropical Trees of Florida and the Virgin Islands: A Guide to Identification, Characteristics and Uses” Pineapple Press Inc, 2009
6) David W. Nellis “Seashore Plants of South Florida and the Caribbean: A Guide to Identification and Propagation of Xeriscape Plants” Pineapple Press Inc, 01/gen/1994
7) Cactus and Succulent Journal of Great Britain. Band 19, Nr. 3, London page. 67. 1957
8) Edwin Miner Solá "Arboles de Puerto Rico y exóticos" E. Miner Solá, 2000

Cultivation and Propagation: Pilosocereus royeniiSN|4681]]SN|4681]] is a summer-growing and easy cactus to grow. It makes great potted specimens.
Growth rate: It grows well, though slowly, but it possible to increase the speed of growth to some extent by providing adequate amount of water, warmth, and an all-purpose liquid fertilizer diluted half strength during the active growing season, but it’s susceptible to rotting if too wet. Most plants will offset readily, and clumps can be produced in a few years. It will fill a large pot or pan in time however, so space is needed if it is to show of its best.
Soil: It needs a very porous, slightly acidic potting medium (add pumice, vulcanite, and perlite). Outdoors it does well on poor, rocky soils.
Exposure: It likes a sunny position also blasting sun in summer. If grown indoor provide 4 to 6 hours, or more, direct morning or afternoon sun.
Aerosol salt tolerance: It is very salt resistant and may be grown near the sea.
Wind resistance: It endures strong winds.
Watering: It should be watered regularly in Summer allowing to dry before watering again and kept drier in Winter. It is very drought-tolerant, but seems to do better with a little more water than most cacti.
Hardiness: It can be grown outdoors in frost-free climates, needs anyway to kept above 12 °C and dry in winter. But it can tolerate temperatures down to 5° C (or even 0° C) for very short periods if very dry and ventilated. During winter month, put them in a cool luminous place and encourage them to enter winter dormancy by withholding water and fertiliser over the winter as they will etiolate, or become thin, due to lower levels of light.
Maintenance: Repot every two years. Needs lots and lots of space to grow, use large shallow container or bowl filled with very porous compost. It like pots with generous drain holes.
Ornamental uses: The striking candelabra growth form and minimal care required make this an excellent landscape accent plant on dry sites. It is also a robust plant that helps to stabilize poor soils. Young specimens do well as pot plants if given at least 5 hours of direct sunlight each day.
Edible uses: The sweet fruits may be eaten fresh, made into a beverage or pre-served as a condiment.
Traditional uses:The skeletal open network of wood fibres remaining after the death of the cactus has been used in various craft work.. Chunks of the branches have been used as bait in fish traps.
Medicinal uses: Reports of medicinal uses were not found.
Pest & diseases: They are susceptible to fungal diseases if overwatered, but are not nearly as sensitive as many other cacti, especially in warm weather. If kept damp through cold periods, they will invariably suffer.
Remarks: Do not use fatty products (like horticultural oil, neem oil, mineral oil, and insecticidal soaps) that can fade and ruin the characteristic blue colouration of the epidermis!
Propagation: Seeds or cuttings. The seeds may be germinated and grown in containers. Their main requirements consist of high humidity levels, free-draining soil mix, and enough water, light, and nutrition.