Monographs Details: Cephalocereus royenii (L.) Britton & Rose
Authority: Britton, Nathaniel L. Flora Borinqueña.
Description:Species Description - Locally abundant and conspicuous in the dry southern and southwestern parts of Porto Rico from the vicinity of Salinas westward, at low elevations, and seen also at Cape San Juan, this large, stout cactus sometimes forms groves, with many plants growing together, as observed by us near Paso Seco and Guanica; it inhabits plains and hillsides, and grows also on the small islands Desecheo, Mona, Cayo Icacos, Vieques and Culebra, ranges eastward through the Virgin Islands, and occurs also on St. Kitts and Antigua. Cephalocereus (Greek, head-Cereus, with reference to the hairy, or woolly tops of the branches), a genus established by the German botanist Pfeiffer in 1838, comprises about 48 species of upright, usually branched, columnar cacti, their leafless joints elongated, ribbed and grooved, the numerous areoles bearing tufts of spines, the upper areoles bearing also long hairs, or, in some species, long, weak bristles. The flowers, solitary at upper areoles, are fleshy, opening fully at night; they have a bell-shaped, or short-funnelform tube, several or many, short-segments, and numerous, short stamens; the subglobose ovary is spineless, and contains many ovules; the style is long, and exserted. The fruit is a large, globose, depressed-globose, or short-ellipsoid berry, containing many, small, black, or brown seeds, and falls to the ground without opening. Cephalocereus Royeni (commemorates Adrian van Royen, distinguished Dutch botanist, who lived from 1705 to 1779), is at first a simple column, but later branches either from near the base, or above, and may reach a height of about 8 meters, with a short trunk sometimes 0.3 meter in diameter; the stout, upright, or ascending branches are from 8 to 15 centimeters in diameter, with from 7 to 11 prominent ribs, varying in color from green to blue, and usually glaucous when young; the areoles bear clusters of needle-like spines, from 1 to 6 centimeters long, yellow, fading to gray, the upper ones, where the flowers may appear, also bearing tufts of long, white wool; the flowers are greenish-yellow, or purplish outside, and from 4 to 7 centimeters long, the broad tube nearly bell-shaped; when fully expanded, at night, they are from 4 to 5 centimeters broad, the inner segments lance-shaped, pointed, pinkish or nearly white. The depressed-globose berry is green, or reddish, about 5 centimeters in diameter, its pulp red, the seeds black, and shining; the withering corolla is persistent on the fruit. Mrs. Horne's painting was made at 9 O'clock in the evening; she observed that the flower began to open at 5 O'clock in the afternoon, and that it is malodorous.

Discussion:Sebucán Dildo Family Cactaceae Cactus Family Cactus Royeni Linnaeus, Species Plantarum 467. 1753. Cereus Royeni Miller, Gardeners' Dictionary, edition 8, no. 7. 1768. Cephalocereus Royeni Britton and Rose, Contributions from the United States National Herbarium 12: 418. 1909.