Portulaca molokiniensis (portulacaceae), a New Species from the Hawaiian Islands

Hobdy, Robert W.
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University of Hawaii Press
Portulaca molokiniensis is a distinctive new species from the arid islands of Molokini and Kaho'olawe. It is clearly distinguishable from its closest relative, Portulaca lutea , by its spinose seeds, extended peduncle-like apical internodes, many-flowered capitate inflorescences, broad, decussate, imbricate leaves, larger flowers, long, sinuous style branches, and cespitose habit. Portulaca molokiniensis occurs in extremely dry coastal sites on leeward rainshadow islands in Hawai'i, well separated from P. lutea which occurs only on moist windward coastal sites. The new species of Portula ca described here was first collected by Charles N. Forbes on Molokini in February 1913. In a publication appearing later that year (Forbes 1913) he identified it as P. lutea Soland. ex G. Forster. It was collected again at the same locality on 13 October 1925 by Harold S. Palmer and identified by Edward L. Caum (Caum 1930) again as P. lutea. It was not documented again until 1978-1984 when it was collected twice on Molokini and three times on Kaho'olawe by various individuals and botanical survey parties (Stemmermann, Char, Higashino and Yosida 1979; Corn, Char, Clarke and Cuddihy 1980; Clarke 1982). It was only during the most recent surveys that these plants were recognized as being possibly distinct from Portulaca lutea. In order to evaluate their status, I initiated a study which included detailed observations and measurements of plants growing at both the Molokini and Kaho'olawe localities, similar observations and measurements of plants growing under cultivation on Maui, and herbarium studies at the Bishop Museum in Honolulu. These studies showed that the Molokini and Kaho'olawe plants possess a number of charactersistics distinguishing them from P. lutea as it occurs throughout its entire Pacific range.
Hobdy RW. 1987. Portulaca molokiniensis (portulacaceae), a new species from the Hawaiian Islands. Pac Sci 41: 64-67.
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