Recent Observations on the Plants of Nihoa Island, Northwestern Hawaiian Islands

Abstract

Terrestrial plants on Nihoa Island were censused, mapped, and collected during four expeditions to the island between May 1980 and May 1983. Distribution, abundance, and phenology of the vascular plants are reported, including maps and population estimates for the rarer species. With the possible exception of the exceedingly rare Amaranthus brownii, the island's endemic plants are present in small but stable populations. A total of 7 months of field work, including the first extended winter expedition to the island , permitted exhaustive searches for rare species and opportunities to estimate populations of winter annuals. Apparently, only one alien plant, Portulaca oleracea, is abundant on the island. A second alien species, Nephrolepis multiflora, probably reached the island naturally via wind or bird dispersal and occurs in very limited numbers.