Moonlit Marvel: Discocactus zehntneri

A rare, night-blooming gem prized for its woolly cephalium and enchanting fragrance.

1. Origin & History of Name: The genus name Discocactus is derived from the Greek diskos (flat plate), referring to its characteristic flattened-globular shape. The specific epithet zehntneri honors Leo Zehntner, a Swiss biologist and naturalist who significantly contributed to the study of Brazilian flora in the early 20th century. It was formally described by Britton and Rose in 1922.
2. Morphology: This cactus features a globose, dark green epidermis with numerous costae (ribs) lined with small, pectinate spines that lay flat against the body. Upon reaching maturity, it develops a cephalium—a specialized structure at the apex composed of dense white wool and bristles—from which nocturnal, tubular white flowers emerge.
3. Habitat & Origin: This is a wild species native to the rocky, arid regions of Bahia, Brazil. It grows in quartz-rich, sandy soils. While common in cultivation, wild populations face pressure from habitat loss; therefore, purchasing nursery-grown specimens is essential for conservation.
4. Cultivation Profile:
   • Substrate: A strictly mineral-based mix is required. Use a blend of crushed gravel, perlite, and coarse sand with minimal organic matter to prevent root rot.
   • Light: Requires bright, indirect sunlight. In the intense Indian summer, provide 50% shade cloth to avoid scorching the epidermis.
   • Water/Dormancy: Water sparingly during the growing season (March–October), allowing the medium to dry completely. In the Indian monsoon and winter, maintain a strict dry dormancy to protect the sensitive root system from humidity-induced decay.
5. Scientific/Historical Anecdote: Unlike most cacti, members of the genus Discocactus stop growing vegetatively once the cephalium forms. All the plant's energy is then redirected into this specialized "head" for the sole purpose of producing flowers and seeds, making the appearance of the woolly cap a milestone for collectors.