Pachypodium geayi is an extraordinarily decorative bottle-shaped tree, 4-7(-8) m high whit stem and branches metallic grey thick and succulent. It strongly resemble cereiform cacti, with highly succulent, cylindrical stems armed with sharp spines.
P. geayi is often confused with the more common Pachypodium lamerei, but easily distinguished by having thinner leaves accented with a prominent midrib of a different colour than the rest of the leaf and in the hairs which adorn the young branches and the leaves.
P. geayi is one of the largest of the Madagascar species and may be regarded as more decorative than Pachypodium lamerei.