Poa acicularifolia subsp. ophitalis
Common name
ultramafic cushion poa
Synonyms
None (first described in 1986)
Family
Poaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Grasses
Chromosome number
2n = 28
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 – Naturally Uncommon | Qualifiers: RR, Sp
Previous conservation statuses
2012 | At Risk – Naturally Uncommon | Qualifiers: RR, Sp
2009 | At Risk – Naturally Uncommon
2004 | Range Restricted
Distribution
Endemic. New Zealand: South Island (eastern Nelson and western Marlborough).
Habitat
Subalpine. An ultramafic endemic confined to ultramafic soil and scree.
Detailed description
Small, tufted blue-green perennial with tufts usually aggregated or with rhizomes interconnecting to form loose mats. Plants 100–200 mm at flowering with culms far overtopping leaves, arising from a woody, much-branched rhizome, with wiry, very long-creeping roots at nodes and numerous fine rootlets; branching intravaginal; leaf-blades disarticulating at ligule. Leaf-sheath light cream to later greyish brown, much wider than leaf-blade, glabrous, membranous, sparsely ribbed; margins very wide hyaline. Ligule 1–5 mm, apically glabrous, tapered, entire, abaxially scabrid near base or smooth, occasionally extending as a rim-like membranous contra-ligule. Leaf-blade 5–25 × c. 0.5 mm, involute, erect, firm, rigid, glabrous; margins sparsely prickle-toothed, slightly narrowed to firm abruptly shortly curved, sometimes pungent tip. Culm 30–150 mm, with 1–2 small cauline leaves, internodes glabrous. Panicle 15–35 mm, lax; rachis glabrous, branches capillary, smooth or very finely scabrid, with 1–2 spikelets at branchlet tips. Spikelets 4–8 mm, 2–5-flowered, light grey-green. Glumes subequal, 2.0–3.5 mm, 3-nerved, elliptic-ovate, midnerve scabrid near subobtuse tip, margins often finely scabrid. Lemma 3–4 mm, 5-nerved, oblong-elliptic, obtuse, short-pubescent throughout lower ⅓ to ½ but central internerves sometimes glabrous, scabrid above on midnerve and occasionally towards tip; margins scabrid above. Palea 2.5–3.5 mm, keels ciliate-scabrid, interkeel minutely hairy on lower ½. Callus ringed by short soft hairs. Rachilla 0.5–1 mm, usually ciliate; prolongation twice as long. Lodicules 0.5 mm. Anthers 1.8–3 mm. Seeds c. 1.5–2 × 0.5 mm.
Manaaki Whenua Online Interactive Key
Similar taxa
Most likely to be confused with Poa colensoi Hook.f., which is a highly variable species. The P. colensoi form present on ultramafic substrates differs from P. acicularifolia subsp. ophitalis by the scabrid rather than smooth upper leaf-blades, and short-hairy rather than almost glabrous or shortly scabrid lemmas. Poa acicularifolia Buchanan subsp. acicularifolia is confined to calcareous substrates and differs by its tightly compact, mat-forming growth, and shorter, rigid, cartilaginous, falcate leaves.
Flowering
October–December
Fruiting
December–March
Propagation technique
Easily grown in a small pot in an alpine house. Resents humidity and does best in free draining, base-rich soils.
Threats
An ultramafic endemic, which is naturally restricted to small areas of suitable habitat within the subalpine zone of this rock type. There are currently no known threats to this grass.
Etymology
poa: Meadow grass
Where To Buy
Not Commercially Available
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (June 2005). Description modified from Edgar and Connor (2000).
References and further reading
Edgar E, Connor HE. 2000. Flora of New Zealand. Vol. V. Grasses. Manaaki Whenua Press, Christchurch, NZ. 650 p.