Poa acicularifolia subsp. acicularifolia
Common names
limestone cushion poa
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Grasses
Detailed description
Small, blue-green perennial grass forming diminutive, compact, tight, interlacing mats, 100–150 mm at flowering. 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 stiff, rigidly cartilaginous, falcate, 5.0–25.0 × c.0.5 mm diameter, involute, glabrous; margins sparsely prickle-toothed, slightly narrowed to firm abruptly shortly curved, sometimes pungent tip. Culm 30–100 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 × 0.5 mm.
Similar taxa
Most likely to be confused with Poa colensoi Hook.f., which is a highly variable species. The most common form of P. colensoi present in the north-eastern South Island differs from P. acicularifolia subsp. acicularifolia by the longer, erect, firm rather than rigidly cartilaginous falcate leaves, scabrid rather than smooth upper leaf-blades, and short-hairy rather than almost glabrous or shortly scabrid lemmas. Poa acicularifolia subsp. ophitalis Edgar is confined to ultramafic substrates in eastern Nelson and differs by its more open, rather loosely interconnected rather than tightly compact mat-forming growth habit, and longer, less rigid, erect rather than falcate leaves.
Distribution
Endemic. New Zealand: Marlborough, North and Central Canterbury.
Habitat
Montane to subalpine grassland overlying calcareous rocks and soils. Also on limestone bluffs and screes.
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | At Risk – Naturally Uncommon | Qualifiers: RR
Threats
Potentially threatened by the spread of hawkweeds (Hieraceum spp.) and grasses (such as chewings fescue (Festuca rubra subsp. commutata) and cocksfoot (Dactylis glomeratus L.)) in the limestone habitats it favours. At present there is no documented evidence of decline but careful monitoring is needed at key sites to be sure this grass remains secure. Current observations (which lack hard data) suggest it still exists as stable populations within its main known habitats.
Detailed taxonomy
Genus
Family
Synonyms
Poa acicularifolia Buchanan
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
October–December
Fruiting
November–April
Propagation technique
Easily grown in a small pot in an alpine house. Resents humidity and does best in free draining, base-rich soils.
Other information
Etymology
poa: Meadow grass
Manaaki Whenua Online Interactive Key
NVS code
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.
POAASA
Chromosome number
2n = 28
Previous conservation statuses
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel 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: DP, RR
2012 | At Risk – Naturally Uncommon | Qualifiers: RR
2009 | At Risk – Naturally Uncommon
2004 | Range Restricted
Referencing and citations
References and further reading
Edgar E, Connor HE. 2000. Flora of New Zealand. Vol. V. Grasses. Manaaki Whenua Press, Christchurch, NZ. 650 p.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (June 2005). Description modified from Edgar and Connor (2000).
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.