The Parkia Tree bears edible seeds that are in Thai known as sa-to. These seeds are arranged horizontally across the bean pods and can clearly be seen from the outside as the seeds are embossed on the skin of the pods.

These pods, known as bitter beans, are in some species spirally twisted, and ths also referred to as twisted cluster beans. The tree is rather uncommon and grows always close to streams. Its flowers secrete a nectar and are pollinated by bats. There are several kinds of Parkia Tree.

The most commonly species is Parkia speciosa, but also Parkia leiophylla, as well as two subspecies from Central Thailand, i.e. Parkia sumatrana and Parkia timoriana, are prevalent, of which the first has its seeds arranged diagonally across spirally twisted pods, while the latter has straight pods (fig.).