A New Species of Nototrichium (Amaranthaceae) from Kaua'i, Hawaiian Islands

Abstract

Nototrichium divaricatum Lorence from the Hawaiian Island of Kaua'i, distinguished from its congeners by its compoundly branched inflorescences with divaricate branches and shorter spikes, is described and illustrated, and its affinities within the genus are discussed. Nototrichium (A. Gray ex Hillebrand) Hillebrand is a Hawaiian endemic genus of shrubs or occasionally small trees restricted to mesic and dry forest and shrubland communities. Nototrichium was originally established as a genus by Hillebrand (1888) to encompass three species: N. sandwicense Hillebrand (with two additional varieties), N. humile Hillebrand, and N. viride Hillebrand. Subsequently, Schinz (1931) described an additional species, N. fulvum Schinz. In a series of publications Sherff (1950a, b, 1951a, b, 1962) described over 20 varieties of N. sandwicense. St. John (1980) later described a new variety of N. viride. Many of these taxa were based on variable characters, such as pubescence density, leaf size, and inflorescence shape and length. In the most recent treatment of the genus, Wagner et al. (1990) recognized only two species, N. humile and N. sandwicense, with no infraspecific categories. The former species is federally listed as endangered and restricted to O'ahu (Wai'anae Mts.) and one locality on East Maui, whereas the latter species is much more common and widespread, occurring on all eight of the main Hawaiian Islands: Kaua'i, Ni'ihau, O'ahu, Moloka'i, Lana'i, Maui, Kaho'olawe, and Hawai'i (Wagner et al., 1990). Nototrichium belongs to subfamily Amaranthoideae based on its bithecal (tetrasporangiate) anthers and pollen of the Amaranthus-type (Eliasson, 1988). The following combination of characters distinguishes it from other genera of native and naturalized Amaranthaceae in Hawai'i: shrubby or arborescent habit, densely silky strigose pubescence, opposite leaves, flowers in terminal spikes, flowers and fruit ascending, and flowers 4-merous. Nototrichium is clearly related to the primarily Old World genus Achyranthes L., which differs by its reflexed flowers and fruit and 5-merous flowers, although certain anomalous species, such as A. arborescens R. Brown from Norfolk Island, have 4-merous flowers (Hillebrand, 1888; Wagner et al., 1990). Nevertheless, the pollen structure of Nototrichium closely resembles that of certain species of Cyathula Blume (Eliasson, 1988). An unusual species of Nototrichium not corresponding with any of the described taxa was first collected on the Na Pall coast region of northwestern Kaua'i by Steve Montgomery in 1985 and was relocated in 1991 by Kenneth R. Wood, staff member of the National Tropical Botanical Garden. Further exploration of this rugged area by Wood revealed a continuous band of this species comprising an estimated 1000 individuals growing on north-facing cliffs in Kalalau, Pohakuao, and Honopu valleys between ca. 600 and 1100 m elevation. Critical study of the specimens leaves no doubt that they represent a new species of Nototrichium. Nototrichium divaricatum Lorence, sp. nov. TYPE: Hawaiian Islands (U.S.A.). Kaua'i: Hanalei District, Kalalau rim, 3200 NW-facing cliffs below and E of first Kalalau lookout, diverse montane precipitous slopes with small pockets of forest and vertical cliffs, 10001100 m, 15 Sep. 1991, K. R. Wood, M. Query & D. Boynton 1227 (holotype, PTBG; isotypes, BISH, F, MO, NY, US). Figure 1. Species inflorescentia pluriramosa, ramulis divaricatis, ramulis primariis paribus 1(-2), interdum ramulis secondariis instructis, spicis brevioribus 5-20(-35) mm longis, (4-)8-30(-66) floribus a congeneribus bene distincta. Densely branching shrubs 0.3-2 m tall, most parts densely sericeous with straight, silvery-white, appressed, simple hairs 0.2-0.6 mm long; twigs densely white-sericeous, terete or slightly quadrangular, 1.5-2.5 mm diam., the internodes (0.5-)16.5 cm long; leaves opposite, petiolate, equal; petioles 3-12 x 0.8-1.5 mm, adaxially flattened or concave, narrowly winged distally, densely sericeous; lamina elliptic, narrowly elliptic, lanceolate, rarely rhombic-elliptic or obovate-elliptic, (2-)37.5 x (0.6-)1-4.6 cm, chartaceous, adaxially NovoN 6: 64--67. 1996. This content downloaded from 157.55.39.136 on Thu, 19 May 2016 05:15:05 UTC All use subject to http://about.jstor.org/terms Volume 6, Number 1 1996 Lorence Nototrichium divaricatum 65