Empodisma robustum Wagstaff & B.R.Clarkson, 2012

Wagstaff, Steven J. & Clarkson, Beverley R., 2012, Systematics and ecology of the Australasian genus Empodisma (Restionaceae) and description of a new species from peatlands in northern New Zealand, PhytoKeys 13, pp. 39-79 : 57-58

1. Empodisma robustum Wagstaff & B.R.Clarkson sp. nov.

Holotype.

( Fig. 8 ) New Zealand, Waikato, Hoe-O-Tainui, R. Mason, N.T. Moar 6750, 6/12/1958, CHR11159.

Etymology.

robustum describes the robust stature of Empodisma robustum .

Description.

Culms dark green, 38-139 cm in height (reportedly> 200 cm when supported by associated shrubs), 0.9-2.2 mm in diameter at the base, branching profusely. Leaf sheaths open, closely appressed, 5.2-21.0 mm in length, borne at intervals of 20.0-70.0 mm, light green to light brown early in the season maturing dark brown; mouth ciliate with a tuft of woolly white hairs. Lamina strongly reflexed from leaf sheath, 2.2-7.5 mm long, light green when young maturing dark brown. Spikelets brown; male spikelet 6.8-9.0 mm long, anthers 1.9-2.5 mm; female spikelet 5.8-8.9 mm; nutlets dark brown approximately 2.7 mm long. Flowering Aug.-Oct. See Figure 9 .

Comments.

Many herbarium specimens of Empodisma robustum include only the upper portion of the plant. These specimens may be difficult to distinguish from the larger specimens of Empodisma minus . Quality specimens should include a rhizome and the base of the culms, from which the distinguishing measurements are taken. Most collections of Empodisma robustum are either sterile or male, and the few females generally lack mature fruits. A chromosome count of 2n=24 was reported from plants collected at Moanatuatua Bog ( Briggs 1966, Johnson and Cutler 1973).

Representative specimens.

New Zealand, Lake Tangonge, H. Carse, H.B. Mathews, 25 Oct 1920, CHR295186; New Zealand, Moanatuatua Bog, W.F. Harris, 20 Nov 1951, CHR85625; New Zealand, Motutangi Swamp, T. Seymour, 15 July 1976, CHR287072; New Zealand, Tauhei, H. Carse, Aug 1925, CHR295191; New Zealand, Opuatia Bog, immature ♀ flowers J.T. Taylor, 27 July 1987, WAI8520; New Zealand, Torehape, not flowering, R.H. Chitty, WAI3280; New Zealand, Moanatuatua Bog, not flowering, R. Thompson, 3/77, WAI2099; New Zealand, Moanatuatua Bog, immature flower buds, H. Beaton 3/77, WAI2098; New Zealand, Kopouatai Peat Dome, immature flower buds, P.J. de Lange, 14 Mar 1988, WAI9008; New Zealand, ♂ in flower, R. Irving, M. Skinner, 12 Oct.1983, WAI 422; New Zealand, Tairua Ecological District, not flowering, B.R. Clarkson, 3 Feb 1998, WAI 16755; New Zealand, MoanatuatuaBog, not flowering, H.J. Beaton, 16 Aug1976, WAI 1100; New Zealand, Moanatuatua Bog, not flowering, K. Thompson 3/77, WAI 2100; New Zealand, Kaitaia, not flowering,W.F.B. Oliver, 26 Feb 1929, WELT19806; New Zealand, Ohaupo Swamp, ♂ flowers, T.F. Cheeseman, WELT19805; New Zealand, Ohaupo Swamp, not flowering, W. Petrie, WELT19804; New Zealand, Ohaupo Swamp, ♂ in flower, W. Petrie, WELT19803; New Zealand, Ohaupo Swamp, ♂ flowers, W. Petrie, WELT19802; New Zealand, Maitahi shrubland, not flowering, A.R Jamieson, AK231291; New Zealand, Rukuhia Swamp ♂ and ♀ plants in flower, L.M. Cranwell 18/34, AK109372; New Zealand, Lake Ohia, ♂ flowers, R. Cooper, R. Mason, N. Moar 1 Aug 1949, AK35820; New Zealand, Torehape Peat Dome ♂ flowers, A.E. Wright 10576, AK215859; New Zealand, Whangamarino Swamp, ♂ flowers, plants up to 1.2 m tall, E.K. Cameron 8839; AK234026; New Zealand, Kaihu Valley, ♂ flowers, A.R. Jamieson 30 Oct 1999, AK286616; New Zealand, Tomarata Lakes, not flowering, M.E. Young 20 March 2007, AK299780; New Zealand, Moanatuatua Peat Reserve, Rukuhia, ♂ flowers, F.J. Newhook July 1979, AK304253; New Zealand, Rukuhia Swamp, separate plants with ♂ and ♀ flowers, L.M. Cranwell 18/34, AK109373; New Zealand, Mangawhai Black Swamp, immature ♀flowers, M.E. Young 18 July 1999, AK239846; New Zealand, Mercer Swamp, P. Hynes 15 Feb 1964, AK101004; New Zealand, Tomarata Lakes, with few ♀ flowers, M.E. Young 20 March 2007, AK299780; New Zealand, Lake Ohia, ♂ flowers, A.E. Wright 10554, AK232056; New Zealand, Lake Ohia, ♀ flowers and fruits, A.E. Wright 10555, AK232055; New Zealand, Tokerau Beach, M.E. Young, L.J. Forester 17 Oct 2006, AK306920; New Zealand, Lake Ohia, ♂ flowers, J.E. Braggins 87/87A, AK304249.

The acronym for the University of Waikato herbarium was recently changed from WAI to WAIK. We cited the older WAI acronym which appeared on specimen labels that we studied.

Distribution.

New Zealand endemic ranging from North Cape southwards to approximately 38° S latitude.

Habitat.

Empodisma robustum is restricted to ombrotrophic raised peat bogs where it often coexists with Sporadanthus ferrugineus , fens and gumland heathland peats. Locally abundant, but populations becoming fragmented by intensive land use.

Conservation status.

Widespread drainage and conversion to pasture has dramatically reduced the extent of raised peat bogs in Northland and Waikato. This unique ecosystem is severely fragmented and provides habitat for a number of rare plant species such as Sporadanthus ferrugineus ( de Lange et al. 1999) and Dianella haematica (Heenan and de Lange 2007). However, Empodisma robustum is still relatively common in shallower/younger peat systems, and probably does not yet qualify as a threatened species. We recommend that its conservation status be regularly reviewed.

Figures

Figure 8. Type of Empodisma robustum, N 56 R. Mason, N. T. Moar 6750, 6 / 12 / 1958, CHR 11159.

Figure 9. Morphological characteristics of Empodisma robustum. A Vegetative shoot with attached leaves and flowers (actual size) B Rhizomes with emerging vegetative shoots (2.5 x actual size) C Vegetative shoot with attached pistillate flower D Pistillate flower with attached bracts E Gynoecium F Mature nut G Vegetative shoot with attached staminate spikelet H Staminate flower with attached bracts I Staminate flower. Scale bar = 1 mm.