Pachypodium baronii subs. windsorii is a remarkable caudiciform plant, 0.50-1.50 m high, with a grotesquely swollen, flask-shaped trunk that gives rise to several slender, twisting, mildly spiny branches, each of which carries a sparse crown of simple leaves.
It is a local or morphological form of Pachypodium baronii smaller in all parts, but commonly used to be know as a separate species and very popular with 'fat plant' collectors. The showy trumpet-shaped red flowers also held on much shorter peduncles.
It is the only red-flowered member of the genus.