Stapelianthus decaryi


No synonyms are recorded for this species name.


Stapelianthus decaryi is native to Talanaro in the South East Malagasy Republic and is primarily found in Southern Madagascar near Anosy on the eastern shore of the Ranofotsy Lagoon. The species typically grows in open areas, often on gneiss rocks with an acidic substrate, and can be found in association with other succulent plants such as Rhipsalis baccifera ssp. horrida, Plecranthus sp., and poikilohydric species such as Coleochloa and Xerophyta dasylirioides.


Stapelianthus decaryi is a low-growing succulent that forms compact clumps and produces small, cream-colored flowers with red spots and white spiny papillae. The stems of this plant are decumbent-erect, deciduous, and measure 3-10 cm in length with a diameter of 5-15 mm. They are smooth, gray-green in color, and dotted with red-brown, with flattened conical tubercles along the ridges. The stems suddenly taper into rudimentary leaves that are 2-4 mm long and persist as dry whitish spiny tips. The inflorescences of this plant are 1 to 4-flowered and produced from the base of younger shoots. The flowers are 12-25 mm in diameter with stalks that are 5-8 mm long and 2 mm wide. The sepals are 4-7 mm in length, lanceolate, and subulate with an acute tip. The corolla is 2.5 cm across and has a broad cylindrical tube 1-1.3 cm in length, with a pale brown exterior spotted with red-brown and a cream-colored interior. The lobes of the corolla are broadly triangular, acute, reflexed, and about 8 mm in length, with a pallid upper half and spine-tipped papillae. The corona is purple in color, and the pollinia are 0.5 by 0.3 mm in size with wings of the translator that are approximately 0.2 mm long. The flowers emit a foul odor similar to a dead, rotting animal that has been baked in the sun and are highly attractive to flies, which serve as the primary pollinators of the plant. In some cases, flies even lay eggs on the flowers. The fruit of Stapelianthus decaryi are typical twin seed horns (follicles) that can grow up to 10 cm long and 8 mm wide, and are narrowly fusiform and acute in shape. They may not appear until a year after the flowers have bloomed.


Stapelianthus decaryi is a xerophytic plant that can thrive in dry soil. It is not difficult to cultivate, but it does benefit from slightly warmer winters compared to other species. This plant grows relatively quickly, producing large clumps and easily flowering, and will readily offset to form new plants. It prefers a very porous mineral cactus mix soil with a pH between 7.5 and 8.5, but too rich a compost can cause excessive elongation. The plant needs plenty of root space, so it should be repotted every other or two, or when it has outgrown its pot, using a pot with good drainage. Stapelianthus decaryi requires regular watering, especially during hot summer days, and some light watering if the greenhouse temperatures are elevated during winter. Too much or too little water can lead to rot. In summer, the plant should be fed with a high potassium fertilizer. It is best to avoid freezing temperatures (minimum 5°C) and to ensure low atmospheric humidity during its rest period. This species can grow in full sun, full shade, or half-shade and tends to bronze in strong light, which promotes flowering. However, over-exposure to direct sunlight during the hottest part of the day in summer can lead to sun scorch or stunted growth. Stapelianthus decaryi is relatively resistant to cryptogamic diseases and is quite resistant to the “Black spot” disease of Asclepiads. Rot is only a minor problem if the plants are watered and aired correctly, but fungicides won’t help much if these conditions are not met.


Stapelianthus decaryi can be propagated through offsets produced by mature plants. These offsets can be gently separated from the parent plant and planted in a well-draining cactus mix soil. Another method of propagation is through seed, but this is a slower process. Rooting of cuttings is successful in high temperature conditions, whereas keeping the cuttings dry is crucial. Freshly sown seeds have a high likelihood of germinating.


Stapelianthus decaryi is a superb plant for pot cultivation. It boasts a cascading, clustered habit and makes for an eye-catching display when grown in a hanging container. The stems may turn purple and limp in winter, but they recover in early spring, ensuring that this plant always appears healthy and compact. It is suitable for growing in a cold greenhouse, a frame, or even in a rock garden outdoors.

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