Synonyms:

Pachypodium baronii var. baronii
Pachypodium baronii var. erythreum

Habitat:

Pachypodium baronii originates from the northern regions of Madagascar, making it a local specialty in that area. Specifically, it can be found from Befandriana Nord to Mandritsara. This unique succulent thrives at elevations ranging from 300 to 1200 meters above sea level.
In terms of its natural habitat, Pachypodium baronii typically grows on steep rocks composed of gneiss and granite. It predominantly occupies areas with ample sunlight, although it occasionally adapts to open, dry deciduous forests where it benefits from dappled light. In these environments, it takes advantage of micro-climates that are conducive for succulent growth. Alongside Pachypodium baronii, one might also find companion species such as Pachypodium sofiense, Uncarina species, Aloe bulbillifera, Euphorbia milii, Kalanchoe gastonis-bonnieri, Urera species, and Ischnolepis species.

Description:

Pachypodium baronii is a small, robust succulent shrub with a round or bottle-shaped thick base, called a caudex. It branches out extensively, reaching up to 2 meters or more in height. This species is known for its striking red flowers with a white center, each lasting several days. While not common in cultivation, it’s highly valued and grown by dedicated succulent enthusiasts and collectors worldwide. There are two recognized subspecies: the main one and Pachypodium baronii subs. windsorii. Unfortunately, in its natural habitat, this plant is rare and limited to just two small areas in the north of Madagascar. The location where var. windsorii was first found has been heavily impacted by aggressive collectors.
The caudex, or thickened base, is roughly 20-40 cm long and 20-50 cm wide. It tapers into a few stout, elongated branches that reach 30-50 cm in length and 4-8 cm in diameter, narrowing to about 3 cm. The epidermis, or outer layer, is pale grey or grey-green, often bearing traces of leaf scars. The branchlets are covered in stiff spines, measuring 1.5-7 cm in length and 0.8-1.5 cm in width.
The paired spines are broad and conical, often slightly curved, and measure (2-)6-8(-9) mm long and 1-4 mm in diameter at the base. They start off red and somewhat hairy, but turn brown, becoming smooth and hairless as they mature.
The leaves are arranged in loose clusters towards the tips of the stems. They are elliptic to oblanceolate in shape, 9-15 cm long and 4.5-6 cm wide. They have a leathery texture and are medium green, with a downy underside. The petiole, or leaf stalk, is pale reddish-green and downy, ranging from about 3-25 mm in length. The tips of the leaves are sharp and shiny, with a distinctive pale green midrib and dark green veining.
The inflorescence, or flower cluster, is carried on a stalk (peduncle) and typically holds 3-17 flowers. It measures 16-40 cm in length and 4.5-12 cm in width. The pedicels, which attach the flowers to the stalk, are pale reddish-green and measure 8-23 mm long. The bracts, small modified leaves, are oblong, measuring 5-11 mm in length and 2-2.5 mm in width, and are longer than the sepals.
The showy flowers are tubular with bright red petals and a white center, about 5-6 cm in diameter and 5.5 cm long. The sepals, which protect the flower bud, are dark green, smooth, and persist even after the flower blooms. They are narrowly ovate-acuminate in shape, measuring 2.5-6 mm in length and 1.5-2.5 mm in width.
During its blooming season, which extends from spring through the summer, the plant produces an abundance of these striking flowers.
The fruit of Pachypodium baronii is a twin-horned cylindrical follicle, spindle-shaped and either straight or curved, narrowing at the tip. It is small, about 4-11 cm long, 9-20 mm wide, and 7-10 mm thick. When fresh, it is pale reddish-green with longitudinal lines, but as it dries, it turns pale brown to greenish-brown or dark brown on the outside, and whitish to very pale brown on the inside. The wall of the fruit is about 1 mm thick.
The seeds are oval to elliptical in shape, measuring 6-7 mm in length, and have a pinkish-brown color.

Cultivation:

Caring for Pachypodium baronii can be a rewarding experience. This species, known for its striking appearance, can be successfully grown both indoors and outdoors in warm climates. It’s important to note that it is a slow-growing plant, and over time, it can develop an impressive caudex, or thickened stem.
During the winter months, Pachypodium baronii sheds its leaves and becomes dormant. It’s sensitive to cold temperatures and can be prone to rot if exposed to excess moisture in winter.
For planting, it requires a well-draining cactus potting mix with elements like peat, gneiss, and sand. The pH level should be around 4-5. It’s worth noting that it may need larger pots compared to other species.
When it comes to watering, it’s best to be cautious. In the growing season, sparing watering is recommended to encourage new growth, foliage, and flowering. Make sure the soil is well-drained to avoid waterlogging. From late autumn to mid-spring, refrain from watering entirely. While it’s important not to let the plant completely dry out, especially indoors, it’s equally crucial to avoid overwatering, which can lead to rot. In winter, protect it from rain, and ensure it’s kept on the dry side.
In terms of temperature, Pachypodium baronii thrives in nocturnal temperatures around 12°C and diurnal temperatures up to 40°C in spring to autumn. In winter, it’s crucial to keep it dry and protect it from frost. This species tends to lose its leaves and go dormant in colder months.
Exposure-wise, it prefers full sun to light shade. As for maintenance, it typically doesn’t require pruning, but after several years, it may outgrow its location and need a trim. Remarkably, it has excellent regenerative abilities.
When it comes to repotting, aim to do this every three years. However, handling the plant during repotting can be tricky due to its spines. One effective method is to wrap several layers of newspaper around the trunk where you plan to handle it.
A word of caution: this plant has spines, so handle it with care.

Propagation:

You can propagate Pachypodium baronii through seeds or, less commonly, cuttings. Using fresh seeds usually leads to a high success rate, potentially around 90%. Seedlings tend to grow quite well. To start, soak the seeds in warm water for about 24 hours. Then, plant them in a sterile, sandy mixture that’s about 5 mm deep. This mixture should be made up of fine and coarse river sand, well-rotted compost, perlite, and vermiculite in specific proportions. Keep the mixture consistently moist and at a temperature between 27–35°C for swift germination. The seeds will begin sprouting in just 3-4 days, although they may continue to germinate sporadically for up to 6 months.
Alternatively, you can propagate by removing branches from an older plant if pruning is necessary. These branches should be left to dry for 5 to 8 days before being potted. However, it’s worth noting that cuttings often have a lower success rate in rooting compared to seeds.
Seedlings of Pachypodium baronii tend to grow at a slower pace compared to other Pachypodium species. Young plants develop more conical spines and gradually start to thicken, branch, and even produce flowers. It’s possible for this species to begin flowering at around 4 years of age.

Curiosity:

Pachypodium baronii, like other species of the genus Pachypodium, has a swollen stem called caudex. This is an evolutionary device used by plants fomr semi-arid climate to cope with extreme droughts, as the swollen trunk conserve water and nutrients.

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