Indigenous to American Samoa, widespread in the Pacific. It occurs as a sprawling shrub in sunny littoral habitats, rarely scandent in littoral forest, reported from near sea level to up to 60 m elevation. It is apparently restricted to a single locality in American Samoa, on slopes of the tuff cone island of ‘Aunu‘u, but is much more common in independent Samoa, where it has been collected at least 14 times. The hard seeds are used as marbles and the thorny stems and leaves were formerly attached to long sticks used to snare fruit bats, and to a lesser extent, pigeons and doves. The process of snaring fruit bats is called seu pe‘a, which is also an alternate name for this plant. It can most easily be distinguished from the similar Caesalpinia major in its pinnate, leaf-like stipules instead of subulate ones.
Scandent shrub, often sprawling, or a high-climbing liana, with prickly stems and leaves, tomentose young stems, and leafy, pinnately divided stipules. Leaves bipinnately compound, alternate; rachis up to 70 cm long, thorny, somewhat swollen at the base; pinnae in 3–11 pairs, 10–18 cm long, thorny; leaflets in 5–13 pairs, blades ovate to elliptic, mostly 1.5–3.5 (–6.5) cm long, rounded to subcordate at the base, acute to nearly rounded and mucronulate at the tip; upper surface glabrous, lower finely pubescent; margins entire; petiolules ca. 1–2 mm long. Inflorescence a many-flowered axillary raceme up to 20 cm long, rachis pubescent; flowers functionally unisexual, plants monoecious. Calyx of 5 oblong sepals 6–8 mm long, brown-pubescent on the outside, reflexed at anthesis; pedicel 2–6 mm long, subtended by a linear bract 8–11 mm long. Corolla of 5 free, yellow, petals, 4 of them oblong, 6–9 mm long, the other ca. 5 mm long and marked with red spots. Ovary of female flowers superior, with a simple style; ovary vestigial in male flowers. Stamens of male flowers 10, free, sterile in female flowers. Fruit a prickly oblong pod 5–9 cm long, containing 1 or 2 glossy gray, ovoid to subglobose seeds 1.5–2 cm in diameter. Flowering reported from March to May (but probably of longer duration), fruiting for much of the year.
Distinguishable by its scrambling shrub habit; leafy stipules; thorny stems; thorny, bipinnately compound leaves; small yellow flowers in racemes; pedicels 3–5 mm long; one petal shorter than the others and marked with red; and gray, marble-like seeds in a spiny pod.
48. Whistler 3767—North facing slope of the crater.
49. Whistler 5736—North facing slope of the crater.
50. Whistler 10930—North facing slope of the crater.
Other Samoan Collections: SAVAII: (9). APOLIMA: (2). MANONO: (1). UPOLU: (2).