Rare near steam vents on the flanks of Kilauea volcano; also found on Po'opo'o Islet , South Lana'i. Seed capsules distinctively shell-like and difficult to open, compared to papery capsules in Portulaca villosa. Vulnerable to extinction due to small population size. I suspect it may hybridize with non-native Portulaca pilosa abundant at the Kilauea site. Endemic to
the Island of Hawaii & Lana'i.