As a comment about Pachypodium (Pachypodium brevicaule)
The lowest and weirdest of the Pachypodiums, from the central highlands of Madagascar. This caudiciform succulent grows as a fat, low, amorphous blob with spines and deciduous leaves at the growth points. May reach almost 3 feet wide in old age, rarely over a third that size in cultivation. Usually yellow flowers, though a white-flowered version (leucoxanthum) does exist. Flowers appear early in the growth season.
This species is susceptible to rot on its own roots but much easier and likely a longer lived plant when grafted onto lamerei or geayi. Very seasonal growth pattern. Leaves, buds, and outside of petals are all covered with fine hairs.
Not a beginner Pachypodium, especially on its own roots. Requires warm temperatures, strong light, excellent drainage, and attention to watering. Water more in summer, especially when it's warm, and less in winter. Avoid letting the soil go completely dry. Keep the size of the pot proportional to the size of the plant, and do not overpot.