Description of a Rare New Cliff-dwelling Species from Kaua'i, Schiedea attenuata (Caryophyllaceae) Warren L. WagnerDepartment of Botany, MRC 166, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A. Stephen G. Weller and Ann K. Sakai Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92717, U.S.A.ABSTRACT. A new species of Schiedea is describedand illustrated. It is restricted to the sheer Kalalaucliffs on the island of Kaua'i, the oldest main islandof the Hawaiian Islands. It is most closely relatedto the sea-cliff species S. globosa H. Mann fromO'ahu, Moloka'i, and Maui. Recent collecting activities in the Hawaiian Is-lands by Kenneth R. Wood for his own investigationsof Kaua'i and for the Hawaii Plant ConservationCenter of the National Tropical Botanical Garden,especially rappelling the vast cliffs of Kalalau Valley,Kaua'i, have yielded more than a dozen new speciessince the publication of the Manual of the FloweringPlants of Hawai'i (Wagner et al., 1990). Woodcollected a highly distinctive new species of SchiedeaChamisso & Schlechtendal on one of these rappels.This species, described herein as Schiedea attenu-ata W. L. Wagner et al., is characterized by glossy,succulent, long-attenuate leaves, a short, relativelyopen inflorescence, perfect flowers with recurvednectary shafts, and 5-6(7) carpels. It has been col-lected twice on rappels into Kalalau Valley on theKalahu side below and west of the first lookout(southwesternmost) at 700-800 m. Although thediverse mesic cliff plant communities on the upperKalalau Valley north-facing cliffs are outstandingassemblages of rare species, fewer than 20 individ-uals of this new species were noted by Wood duringhis extensive investigations. The southwestern cor-ner of the upper Kalalau Valley has habitats thatmay harbor additional populations of this rare spe-cies. Plants grown from seed are currently under cul-tivation in the University of California at Irvinegreenhouse as part of a collaborative study on thephylogeny and evolution of dioecy in this endemicHawaiian genus. The extensive Kalalau Valley har-bors about 20% of the species of the lineage towhich Schiedea belongs, including, in addition to S.attenuata, Alsinidendron lychnoides (Hillebrand)Sherff, Schiedea apokremnos H. St. John, S. mem-branacea H. St. John, S. nuttallii W. J. Hooker,and S. spergulina A. Gray var. spergulina. Schiedea and Alsinidendron constitute a mono-phyletic radiation in the Hawaiian Archipelago, basedon the presence of highly specialized floral nectariesand the absence of petals in all species. Nectar iscollected and presented through a hypodermic-likeshaft in Schiedea and at the base of a flap-or cup-like structure in Alsinidendron. In a majority ofthe members of the subfamily Alsinoideae, to whichthe endemic Hawaiian genera belong (Pax & Hoff-mann, 1934; Weller et al., 1990), the nectary isrepresented by a mound of nectariferous tissue bi-sected by a lateral furrow located on the abaxialside of each antesepalous stamen (Thomson, 1942).Ontogenetic studies indicate that the nectary dif-ferences between Schiedea and Alsinidendron rep-resent changes in homologous structures (E. Harrisand Wagner, unpublished obs.). A preliminary phylogenetic analysis by us sug-gests that Schiedea attenuata is the sister speciesof the most widespread species, S. globosa H. Mann,a sea-cliff species found on O'ahu, Moloka'i, andMaui. Both of these species share the derived char-acters of succulent leaves, recurved nectary shafts,and more styles than the typical three found in mostSchiedea species. Schiedea globosa differs in pos-sessing a specialized dense globose inflorescence, asubdioecious breeding system, and a more sprawlinghabit. The phylogenetic analysis suggests that thehermaphroditic condition of S. attenuata may besecondarily derived.Schiedea attenuata W. L. Wagner, Weller & Sakai, sp. nov. TYPE: Hawaiian Islands. Kaua'i: Hanalei District, Kalalau rim, Kalahu side be-low and W of first Kalalau lookout, 300 m E of plane crash [site], [22�8'N, 159039'W, NW NovoN 4: 187-190. 1994.