Where the Pachypodium lealii flower cluster sprouts on old growth, the spines may have already or mostly disappeared from the stem.
Protective apparatus like spines is less important where successful flower, fruit and particularly seed production have already amply ensured reproduction. The old tree has been rewarded many times with flowers, while age has a way of diminishing the vigour in growth.
Should resources suddenly increase for an energetic spurt, as may be caused by the occasional big rain, young stem growth may again be the order of the day. They may then arrive fully equipped with heavy duty thorns, like numerous armed troops on the parapets of a castle not lacking in provisions (Mannheimer and Curtis, (Eds.), 2009; Coates Palgrave, 2002).