Astrophytum ornatum, commonly known as the bishop's cap cactus or monk's hood cactus, is a species of flowering plant in the family Cactaceae. It is endemic to the Central Plateau of Mexico and is the largest and tallest species within the genus Astrophytum.
Description
Astrophytum ornatum is a solitary, cylindrical cactus that can grow up to 2 meters (6.6 feet) in height and 30 centimeters (12 inches) in width. The stem is typically dark green and develops numerous white woolly flakes (trichomes) on its surface, which serve as protection from intense sunlight. The plant usually has 8 ribs, which are often arranged in a spiral pattern. When viewed from above, the star-shaped outline of the ribs gives the cactus its common name "star cactus." The ribs are lined with clusters of spines and are marked with characteristic cross-bands of woolly scales.
Flowers
The cactus flowers throughout the summer, producing canary-yellow blooms that are 7 to 10 centimeters (2.8 to 4 inches) in diameter. The flowers open during the day and close at night, typically lasting for several days. Flowers often appear in bursts of several at once, with multiple weeks passing between flowering events.
Distribution and Habitat
This species is endemic to the Central Plateau of Mexico. It is listed as Vulnerable on the IUCN Red List of Threatened Species (2017 assessment).
Cultivation
Astrophytum ornatum is considered the easiest and fastest-growing species in the genus Astrophytum. It is a rugged plant resistant to root rot and thrives in well-drained soil. It appears dark green when grown in filtered light or shade. An established plant is cold tolerant to approximately 25 °F (−4 °C). The species has gained the Royal Horticultural Society's Award of Garden Merit.
Taxonomy
The binomial name is Astrophytum ornatum (DC.) Britton & Rose. The genus name Astrophytum derives from the Greek words astron (star) and phyton (plant), referring to the star-like appearance of the cactus from above. The specific epithet ornatum means "ornate" or "decorated" in Latin, referring to the distinctive white woolly bands and scales that adorn the stem.
