Species
Rytidosperma nudum
Etymology
Rytidosperma: wrinkled seed
nudum: bare
Common Name(s)
None known
Current Conservation Status
2012 - At Risk - Naturally Uncommon
Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB
Previous Conservation Status
2009 - At Risk - Naturally Uncommon
2004 - Range Restricted
Qualifiers
2012 - RR
2009 - DP, RR
Authority
Rytidosperma nudum (Hook.f.) Connor et Edgar
Family
Poaceae
Flora Category
Vascular - Native
RYTNUD
The
National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
Structural Class
Grasses
Synonyms
Danthonia nuda Hook.f., Notodanthonia nuda (Hook.f.) Zotov
Distribution
Endemic. North Island, Central Volcanic Plateau (Mt Ruapehu), Ruahine and Tararua Ranges.
Habitat
Subalpine to alpine in flushes and bogs.
Features
Diminutive, diffuse tufted grass, leafy at ends of elongating shoots, rooting at nodes; leaves somewhat acute, more or less equal to culms, dis-articulating at ligule. branching intravaginal. Leaf-sheath pale straw-coloured to light grey, glabrous; apical tuft of hairs few, 1-2 mm long. ligule to 0.4 mm. Leaf-blade to 80 mm, folded, narrow, rather soft, glabrous. Culm to 100 mm, internodes glabrous. Panicle small, erect, to 30 mm, of few spikelets on short pedicels; rachis and pedicels slender, closely short-scabrid and some longer hairs at branch axils. Spikelets usually 3-flowered, awns barely exserted from glumes. Glumes purplish centrally, ovate, obtuse, more or less equal, 3.5-7.0 mm long; lower 3-5-nerved, upper 3-nerved. Lemma 2.3-3.5 mm, 5-9-nerved, upper and lower rows of hairs very sparse, upper row usually of small marginal tufts with a few scattered hairs, elsewhere glabrous, margins with scattered hairs; lobes 0.2-0.5 mm, acute to acuminate, not awn-tipped; central awn 1-2 mm long, erect, column scarcely evident. Palea 2.4-2.8 mm long, reaching base of awn, sinus, = upper lemma hairs, inter keel glabrous, margins occasionally with a few long hairs. Callus c.0.3 mm long, a few marginal hairs not reaching lower lemma hairs, or marginal tufts denser, slightly overlapping lower lemma tufts. Rachilla 0.5-0.8 mm. Anthers 0.7-0.8. Seed not seen.
Similar Taxa
Recognised by the awn of the lemma 1-2 mm long, and the lemma which is 2.3-3.5 mm, 5-9-nerved, with the upper and lower rows of hairs very sparse, and the upper row usually comprised of small marginal tufts with a few scattered hairs, otherwise glabrous. The lemma margins have scattered hair and lobes 0.2-0.5 mm, which are acute to acuminate. Its relationship to the other indigenous species is not clear though it seems closest to R. australe and R. pumilum. The small, few-flowered spikelets and absence of seed are useful field characters.
Flowering
November - January
Fruiting
Not known
Propagation Technique
Grows easily enough from the division of whole plants
Threats
A very local endemic, rarely collected.
Chromosome No.
2n = 24
Endemic Taxon
Yes
Endemic Genus
No
Endemic Family
No
Where To Buy
Not commercially available. 
Taxonomic Notes
Some botanists believe that this uncommon species is a naturally occurring, uncommon, sterile hybrid (B.P.J. Molloy pers. comm.; de Lange et al. 2009; de Lange & Rolfe 2010), especially as the seed of this species has never been seen. However, the recent (2012) discovery of this species growing in abundance in alpine flushes on Mt Ruapehu (P.J. de Lange, N.J. Singers, J.R. Rolfe & M.A.M. Renner unpubl. data), in morphologically uniform populations suggests that it is a functional species. Currently this species is listed as Taxonomically Indistinct in Appendix 3 of de Lange et al. (2009) having previously been listed as "Range Restricted" by de Lange et al. (2004). Clearly this status will need to change and as as an interim measure the status of "At Risk / Naturally Uncommon" appended DP [Data Poor], RR [Range Restricted] is here suggested (P.J. de Lange unpubl. data).
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 30 August 2006. Description adapted from Edgar & Connor (2000).
References and further reading
de Lange, P.J.; Norton, D.A.; Heenan, P.B.; Courtney, S.P.; Molloy, B.P.J.; Ogle, C.C.; Rance, B.D.; Johnson, P.N.; Hitchmough, R. 2004: Threatened and uncommon plants of New Zealand. New Zealand Journal of Botany 42: 45-76.
de Lange, P.J.; Norton, D.A.; Courtney, S.P.; Heenan, P.B.; Barkla, J.W.; Cameron, E.K.; Hitchmough, R.; Townsend, A.J. 2009: Threatened and uncommon plants of New Zealand (2008 revision). New Zealand Journal of Botany 47: 61–96.
de Lange, P.J.; Rolfe, J.R. 2010: New Zealand Indigenous Vascular Plant Checklist. Wellington, New Zealand Plant Conservation Network. 164pp.
Edgar, E.; Connor, H.E. 2000: Flora of New Zealand. Vol. V. Grasses. Christchurch, Manaaki Whenua Press. 650 pp.
This page last updated on 17 Jan 2014