Blackbead (Pithecellobium keyense) and cat’s claw (Pithecellobium unguis-cati) are two closely related, shrubby trees that are in the same family and genus—making them a challenge to differentiate.
Both provide several benefits to wildlife. Birds are drawn to their fruits and brightly colored arils (seed coverings) and the tree branches provide protection for nesting birds. They also attract butterflies as host plants and as a source of nectar.
They also have a comparable size and shape, growing to about 15 feet tall and wide. Both have the same unique compound leaf: two sets of two identical leaflets connected at the base, where they attach to the petiole. Their fragrant flowers are similar in color and shape. The seed pods curl (or contorted) when they ripen, and the insides are bright red with black seeds. Each seed has a red cap or arils. The seed pods are very showy and add to the uniqueness of these trees; yet they don’t assist in distinguishing blackbead from cat’s claw.
Here are some key differences: In the Florida Keys, the blackbead has orange to pink flowers but on the Florida mainland, the flowers are often whiter in color. The cat’s claw flower is white to light pink, so it’s not overly helpful in identification. The cat’s claw has thorns while blackbead thorns are fewer and smaller. The distinguishing difference lies in the length of the leaf petioles. The petiolule is a structure that connects the leaflets to the petiole. The petiole connects the leaf structure to a branch. The cat’s claw petiole is longer than the petiolule. The opposite is true of blackbead. Its petiolules are longer than the petiole.