This looks like some sort of Acacia, with an unusual leaf formation: bipinnate, but just two leaflets, each leaflet divided once. Near the road on Waimea Plantation Cottages property on Kauai.
Thank you. That has led me, by some path that I can no longer retrace (a Calliandra key, a photos page, a photo of something that didn't belong on that page), to Pithecellobium, maybe Pithecellobium unguis-cati, common name Catclaw blackbead. The leaf arrangement is right, branch looks good, I think I'm seeing thorns, twisted pods with black beads (new photo attached). Leaf petiole doesn't look hairy enough, and some of the leaf photos I see have whiter, more prominent veins, so maybe some other Pithecellobium.
Thank you Ron B for suggesting in some other thread Marie C Neal's In Gardens of Hawaii (Bishop Museum Press, 1965). I see (pp 400-401) that Pithecellobium dulce, common name Manila Tamarind, or in Hawaii, Opiuma, is commonly cultivated. The flowers are more white than P. unguis-cati, which is supposed to have purplish stamens. The pods twist spirally, which is more the case here. The Opiuma name comes from the resemblance of the seeds to the opium of commerce, not that that helped me any. There is a form with leaves that are variegated for part of the year. On the same page, I was interested to see that the Monkeypod tree, Albizia saman, previously called Samanea saman, used to be called Pithecellobium saman. The drawing on the opposite page shows, along with P. dulce, a Calliandra and an Acacia. [Edited]Wikipedia suggests the common name Madras thorn instead of Manila Tamarind, which is in both parts misleading. Among other junior botanical names are Inga dulcis, Mimosa dulcis, Albizia dulcis, Mimosa edulis, Acacia obliquifolia.
