Our thanks go to Krystyna Szulecka, who posted today’s lovely close-up image in our Botany Photo of the Day Submissions Forum this past weekend.
All but one species included in the succulent Cactaceae are endemic to the Americas. The single exception, Rhipsalis baccifera, is native to the New World, but is distributed throughout the tropical areas of Africa, Madagascar, and Sri Lanka as well. In spite of this geographical concentration, the family's fleshy shrubs, trees, and vines have been naturalized on all but one of the planet's continents (Antarctica). Cactaceae species exhibit a broad diversity of habits and sizes, with plants ranging from the coin-sized Blossfeldia through to Pereskia, a genus of leafy, barely succulent shrubs and forest trees that can extend upward of 24 metres. Generally, the Cactaceae species bear solitary, sessile flowers, many of which are exceedingly transient.
Echinopsis is a genus of around 128 species native to the gravelly, sandy soils and hillside slopes of South America. The genus has a number of common names (Easter lily cactus, golden torch, white torch cactus), but derives its scientific name from the Greek for the hedgehog and the sea-urchin, which species' spiny exteriors are thought to resemble. In cultivation, the genus's tough, robust plants thrive in loamy soil, particularly when exposed to a touch of leaf mould and a moderate amount of limestone. Full sun in the spring and overhead, evening-time watering in the summer is recommended by some authors. Individual species demand little maintenance, but gardeners are advised to ensure that the plants are not at any moment over-watered (particularly in winter), for an excess of water leads either to rotting in the roots or to a privation of the dormancy that promotes full flowering in the summer.
Echinopsis spachiana, a columnar species named for the 19th century Alsatian botanist Édouard Spach, generally reaches its apex between 1.5 and 2 metres. The species exhibits heavy basal branching and its exterior bears many yellow and brown protective spines that turn to white as they age. Once the plant has reached 1 metre in height, it is physiologically ready to put forth its beautiful, hairy-tubed flowers, which can sprawl to a diameter of 15cm. in their short (24 hour) lifespan. An outer ring of multiple and apparently independent stamens are united at their base to form a ring known as an annulus or hymen, which serves as a nectar guide for visiting moths.