What is "caesalpinia bonduc"

Nicker nut \Nick"er nut`\ A rounded seed, rather smaller than a nutmeg, having a hard smooth shell, and a yellowish or bluish color. The seeds grow in the prickly pods of tropical, woody climbers of the genus C[ae]salpinia. C[ae]salpinia Bonduc has yellowish seeds; C[ae]salpinia Bonducella, bluish gray. [Spelt also neckar nut, nickar nut.]

Caesalpinia bonduc, commonly known as Gray Nicker, is a species of flowering plant in the senna family, Caesalpiniaceae, that has a pantropical distribution. It is a vine-like shrub that reaches a length of and scrambles over other vegetation. Stems are covered in curved spines. Its gray seeds, known as nickernuts, are buoyant and durable enough to be dispersed by ocean currents.