Origin and Habitat: Madagascar on Isalo mountains,
Altitude: between 300 and 1000 m.
Habitat: It grows on sandstone escarpment, cliffs and rocks with some humus along with other rupicolous vegetation including Euphorbia primulifolia var. begardii, Ceropegia dimorpha, Euphorbia isaloensis, and Aloe isaloensis.

• Pachypodium rosulatum subs. gracilius (H.Perrier) Lüthy
• Pachypodium gracilius Rapan.
• Pachypodium rosulatum var. gracilius H.Perrier

• Pachypodium rosulatum Baker
• Pachypodium rosulatum f. cristata hort.
• Pachypodium rosulatum var. delphinense H.Perrier
• Pachypodium rosulatum var. drakei (Costantin & Bois) Markgr.
• Pachypodium drakei Costantin & Bois
• Pachypodium rosulatum subs. gracilius (H.Perrier) Lüthy
• Pachypodium gracilius Rapan.
• Pachypodium rosulatum var. gracilius H.Perrier
• Pachypodium rosulatum var. stenanthum Costantin & Bois

• Pachypodium rosulatum subs. bicolor (Lavranos & Rapan.) Lüthy
• Pachypodium bicolor Lavranos & Rapan.

• Pachypodium rosulatum subs. cactipes (K.Schum.) Lüthy
• Pachypodium cactipes K.Schum.

• Pachypodium rosulatum subs. gracilius f. cristatum
• Pachypodium gracilius f. cristatum

• Pachypodium rosulatum var. inopinatum (Lavranos) G.D.Rowley
• Pachypodium inopinatum Lavranos

• Pachypodium rosulatum subs. makayense (Lavranos) Lüthy
• Pachypodium makayense Lavranos

Description: Pachypodium rosulatumSN|14782]]SN|14782]] subs. gracilius is a beautiful caudex plant with bright yellow flowers. It is smaller growing than the type and has fewer thinner leaves, slimmer branches and a shorter corolla tube. Height up to 90 centimetres.
Trunk (caudex): The plant trunk is pachycaule, up to 40 centimetres across, and typically short and fat like a more or less regular balloon.
Branches: Narrow, tapering, ascending, reddish-brown, smooth but new shoot lanate up to two centimetres in diameter and reach a height of 60 centimetres.
Spines: Paired conical about 5 mm long.
Leaves: Elliptic to lanceolate, and smaller than other rosulatum about 3-11 cm long, 0,8-2,5 cm wide. Hairless above than beneath.
Flowers: Bright yellow 2-5 together on top of a peduncle 7-40 cm long. Corolla tube thin cylindrical up to 3 cm long, with narrow, ovoid lobes.
Fruit: 6-20 cm long.
Seed: Oblong 6 cm long.
Notes: The species name is often misspelled: "gracilis" or "gracilus".

Bibliography: Major references and further lectures
1) Urs Eggli Illustrated Handbook of Succulent Plants: With 487 Colour Photos.
2) Sara Oldfield Cactus and Succulent Plants: Status Survey and Conservation Action Plan IUCN/SSC Cactus and Succulent Specialist Group
3) Nick Garbutt, Hilary Bradt, Derek Schuurman Bradt Madagascar Wildlife: A Vistor's Guide
4) Stuart Max Walters, James Cullen The European garden flora: a manual for the identification of plants

Cultivation and Propagation: It is one of the most attractive species in the entire genus that can be grown both indoors, as well as outdoors in warm climates. It’s a moderate grower and an impressive caudex can be steadily developed. In the winters it is deciduous, except in very tropical areas.
Soil: Needs a draining cactus potting mix.
Watering: Water sparingly in summer and give extra well-drained soil to avoid waterlogged conditions, no water from November to March. The watering program will change depending on temperatures and stage of growth, but it is best not to let this plant dry out completely for any length of time. Indoors it is best to keep it on the dry side, or it is prone to rot. Outdoors it must be protected from the rain in winter. Do not let this specimen sit damp in cool weather. The older it gets the less water it must receive!
Hardiness: It is sensitive to cold and should be kept totally dry in winter at or around 4°C. Protect from frost. It tends to lose its leave and go dormant in winter (USDA Hardiness zones: 10 – 11).
Exposure: It like full sun to light shade.
Maintenance: This Pachypodium will not require any pruning to look like a very interesting and unusual bonsai, but after several years it can outgrow its indoor location, requiring a 'pruning'. It has amazing regenerative properties.
Repot: Repot the plant every 3 years; this is quite tricky given all the spines. The best way is to wrap several layers of newspaper around the trunk where it is to be handled.
Warning: This plant has spines use caution when handling.
Propagation: Seeds or (rarely) cuttings. Fresh seeds results in a remarkable yield of new plants, perhaps 90% and seedlings grow fairly easily. Soak seeds in warm water for 24 hours before sowing in a 5 mm deep, sterile, moist sandy medium (4 parts fine and 4 parts coarse river sand 1 part sieved, well-rotten compost; 1 part perlite; 1 part vermiculite. Keep the mix moist and at a temperature of 27–35°C to ensure rapid germination. Seed start sprouting in just 3-4 days ( but continue to germinate erratically for about 6 month) they are also propagated by removal of branches from old plant (if they need to be pruned). They should be allowed to dry for 5 to 8 days before potting up, however the cuttings often fail to root. Seedlings grow fairly slowly compared to other Pachypodium species. Young plants have more conical spines and begin early to swell nicely, branch and even flower.