Cereus phatnospermus K.Schum.
Cereus adelmarii, Cereus phatnospermus subsp. adelmarii, Monvillea adelmarii, Monvillea phatnosperma
Cereus phatnospermus is a highly branched cactus with thick fleshy dark green stems with 4 to 5 well-defined ribs and clusters of brown spines. The stems are decumbent or ascending, up to 6.6 feet (2 m) long and 1 inch (2.5 cm) in diameter. The areoles are about 1.2 inches (3 cm) apart. Each areole bears 5 to 6 up to 0.6 inches (1.5 cm) long radial spines and one up to 1.2 inches (3 cm) long central spine. Flowers are white, funnel-shaped, up to 4.8 inches (12 cm) long, and appear from spring to early fall. Fruits are red, egg-shaped, and 3 inches (7.5 cm) long.
The specific epithet "phatnospermus" derives from the Greek words "phatnoein," meaning "hollow out," and "sperma," meaning "seed," and refers to the patterning of the seed surface.
How to Grow and Care for Cereus phatnospermus
Light: Cereus cacti like full sun. They can handle partial shade but thrives during the summer in direct sunlight. Sunny south, east, or west window is a good spot to grow a Cereus indoors.
Soil: These cacti do not like to have "wet feet" and need to be grown in well-draining soil. Use commercial soil mixes for cacti and succulents, or make your own potting mix.
Hardiness: Cereus phatnospermus can withstand temperatures as low as 20 to 50 °F (-6.7 to 10 °C), USDA hardiness zones 9a to 11b.
Watering: From spring to fall, during the active growth period, water thoroughly, but allow the soil to dry out before watering again. With the arrival of fall, gradually reduce the watering frequency.
Fertilizing: During their growing season, Cereus cacti like regular fertilizing. A balanced, water-soluble fertilizer, which has been diluted to 1/4 strength, can be added to the water for each watering. Do not feed during the winter.
Repotting: While Cereus cacti are young, it is recommended to repot each year in early spring to provide them with fresh soil, inspect the root system, and move them to larger pots if necessary.
Propagation: Using stem cuttings is the easiest method to propagate Cereus because seed propagation is a slow process.
Learn more at How to Grow and Care for Cereus.
Toxicity of Cereus phatnospermus
Cereus cacti are non-toxic to humans or animals.
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