Rytidosperma telmaticum
Common name
tarn bristle grass
Synonyms
None
Family
Poaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Grasses
Chromosome number
2n = 24
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – an interim threat classification status has not been assessed by the NZTCS panel.
- Conservation status of New Zealand indigenous vascular plants, 2017 . 2018. Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley. Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | At Risk – Declining | Qualifiers: DP, RR
Previous conservation statuses
2012 | At Risk – Declining | Qualifiers: DP, RR
2009 | Threatened – Nationally Vulnerable | Qualifiers: DP, EF, RR
2004 | Not Threatened
Distribution
Endemic. South Island only, inland from mid Canterbury, the MacKenzie Country and from one site at Conroys Road, Alexandra, Central Otago.
Habitat
A species of intermontane basins, where it grows on the margin of kettleholes, tarns and small ponds.
Detailed description
Small low-growing olive-green tufted tussock-forming, self-compatible grass becoming pallid with many old small straw-coloured bladeless ligule-tipped sheaths below compact intravaginal innovations of 3–4 semi-pungent leaves much less than culms; sometimes open and evidently stoloniferous, rooting and shooting at nodes. Leaf-sheath 5–10 mm, usually glabrous but often long hairy, pale straw-coloured, shining, ridged, broader than leaf blade; upper surface with many fine hairs; apical tuft 0.50–0.75 mm, sparse, spreading. Ligule 0.2–0.3 mm, of fine hairs. Leaf-blade 10–25 × 2 mm, inrolled, glabrous, apex thickened and pointed, ciliate; disarticulating at ligule; undersides very finely prickle-toothed on nerves; margins very finely antrorsely prickle-toothed. Culm 20–200 mm, internodes smooth, shining; nodes 3–5, constricted, often geniculate below; inflorescence internodes 30–70 mm long, sheath sometimes with regular horizontal bands. Inflorescences racemose or a racemose-panicle 5–35 mm, bearing 2–7 spikelets on very short branches or solitary; margins of rachis and branches very finely toothed; pedicels hairy, hairs denser and longer below spikelets. Spikelets 4–5 mm, of 3–5 small closely compact florets usually included by glumes, occasionally upper florets exserted. Glumes c. 4–5 mm long, linear acute, faintly keeled, keels occasionally scabrid above, centrally purple or green, margins chartaceous, 3–5-nerves confluent above and central nerve excurrent; upper surface bearing abundant small white hairs. Lemma 1.50–1.75–2.25 mm, ovate, straw-coloured, sometimes purpled above, 5–7 nerves anastomising below sinus; dense long hairs in two rows less than or equal to lemma apex, upper row of irregular tufts, lower row of denser longer tufts reaching upper row, glabrous below lower row, single pair of marginal tufts at level of rhacilla apex often extending below, upper surface finely hairy; apex tridentate with two 0.2 mm long lateral lobes and finely ciliate mucro in sinus, 0.2–0.5 mm or absent, usually > lobes. Callus 0.10–0.25 mm, rounded-obtuse, disarticulation oblique, marginal hair tufts 0.3–0.5 mm overlapping lower lemma hairs. Rachilla 0.3–0.7 mm, glabrous. Anthers 0.30–0.75 mm, purple. Ovary 0.4–0.5 mm, stipitate; stigma-styles 0.75–1.00 mm. Seed 0.8–1.0 mm, stipitate, broadly ovate.
Manaaki Whenua Online Interactive Key
Similar taxa
Allied to Rytidosperma pumilum, from which it differs by its two rows of conspicuous hairs on the lemma, and by its shorter, rounder callus covered in long hairs.
Flowering
November–February
Flower colours
Violet/Purple
Fruiting
January–May
Propagation technique
Easily grown from fresh seed and by division of whole plants. Best kept in a pot, that is partially submerged in water and placed in the full sun. Dislikes humid conditions.
Threats
Changes to the hydrologic regime of the intermontane basins in which this species mostly occurs, caused by recent (2005+) changes in local agricultural practises, are resulting in increasingly longer periods of dry conditions. This is favouring the spread of weeds which in turn are outcompeting the indigenous turf vegetation in which this species grows. Ongoing deterioration of these habitats means that this species and many of its associates are probably under serious threat of extinction over large parts of their range.
Etymology
rytidosperma: Wrinkled seed
Where To Buy
Not commercially available.
Attribution
Description modified from Molloy and Connor (2005).
References and further reading
Molloy BPJ, Connor HE. 2005. Species novae graminum Novae-Zelandiae III. Two diploid species of Rytidosperma (Danthonieae: Danthonioideae). New Zealand Journal of Botany 43: 721–734.