Monographs Details: Calonyction aculeatum (L.) House
Authority: Britton, Nathaniel L. Flora Borinqueña.
Description:Species Description - Among night-blooming plants, this long-vine has the largest flowers of any found in Porto Rico, is commonly grown in gardens, is spontaneous from seed, and occasionally seen here in thickets at lower elevations in moist districts. Its range extends throughout tropical and subtropical America, north to Florida and Bermuda, and it grows also in tropical parts of the Old World; much planted for ornament, the original natural distribution of the species can not be accurately stated; it was first described botanically as from tropical America. Calonyction (Greek, night-beauty), a genus established by the Swiss botanist Choisy in 1833, has only a few species, natives of tropical regions, differing from Ipomoeas in having the style and stamens longer than the slender tube of the salver-form corolla. They are elongated vines, often high-climbing, with large, alternate, stalked leaves, and large, white nocturnal flowers, their 5 sepals much shorter than the corolla. The style is topped by a round stigma. The fruit is a capsule, splitting when ripe and thus releasing the seeds. Calonyction aculeatum (prickly, but the name is not definitive), is a vine which may attain a length of 10 meters; the sap is milk-white; the stem is smooth, or somewhat roughened, with short, soft processes, (whence the specific name). The thin, smooth, nearly orbicular, pointed leaves are from 5 to 15 centimeters long, sometimes 3-lobed, the base deeply heart-shaped. The stout flower-stalks are shorter than the leaves and bear several, white flowers, or only one; the sepals are from 1 to 2.5 centimeter long, the outer ones tipped by an awl-shaped appendage; the slender tube of the corolla is from 10 to 12 centimeters long, its widely spreading limb from 8 to 10 centimeters wide, each lobe with a broad, green, median band terminating in a tip. The ovoid capsule is about 2 centimeters long, the seeds smooth, or nearly so. Another species, Calonyction Tuba is also illustrated and described in this work.

Discussion:Bejuco de vaca Moon-vine Morning-glory Family Convolvulus aculeatus Linnaeus, Species Plantarum 155. 1753. Ipomoea bona-nox Linnaeus, Species Plantarum, edition 2. 228. 1762. Calonyction aculeatum House, Bulletin of the Torrey Botanical Club 31: 590. 1904 Calonyction speciosum Choisy Mémoires de la société de Physique et d'Histoire Naturelle 6: 441. 1833.