Discocactus heptacanthus
Discocactus heptacanthus is a species of Discocactus found in Brazil, Bolivia, and Paraguay.
Description
Discocactus heptacanthus is a small, solitary cactus characterized by its discoid to nearly globular shape. Its stems, reaching in height and in diameter, possess a pale green to olive epidermis and branched roots. The plant features 9 to 16 prominent, vertically or slightly spirally arranged ribs, which are grooved between the areoles, creating flattened, nipple-shaped tubercles. Each rib bears 2 to 6 oval, sunken areoles, measuring long and wide. The spines vary in color from pale yellow to gray or brown. They are straight or slightly curved and typically consist of a single central spine, long, though this may be absent. Additionally, 3 to 9 radial spines, measuring long, are present. Mature plants develop a woolly cephalium at their apex, a structure high and in diameter. This cephalium, composed of white to dull pastel wool and occasional brown or black bristles up to long, protects the plant's sensitive tip from cold and intense ultraviolet radiation. It is also thought to attract pollinators and is conspicuous even before flowering.The fragrant, white flowers are tubular to funnel-shaped, emerging from the cephalium's edge. They open at night, are pollinated by moths, and measure in length and in diameter. The flower buds are olive green. The naked ovary at the base of the flower is adorned with few naked scales, while the slender floral tube, long, has white scales, with brownish-green ones on the central vein and apex. The inner and outer perianth segments are white, measuring and respectively. The stamens have long filaments supporting long yellow anthers. The style extends, culminating in a 4 to 7-lobed stigma containing ovules arranged in groups of 4 to 5. Fruits are club-shaped, white with a greenish-pink apex, measuring long and wide. They split longitudinally at maturity, retaining persistent floral remnants. Within, shiny, oval black seeds, long, are found, distinguished by a testa covered in numerous nipple-shaped tubercles.