Poa chathamica
Common names
Chatham Islands poa
Biostatus
Native
Category
Vascular
Structural class
Grasses
Detailed description
Light green, dark green to blue-green, widely creeping drooping perennial grass usually forming dense, leafy swards from long, narrow rhizomes, or stiffly erect tufts to 1 m. Leaves about equal to culms; branching extravaginal near plant base, intravaginal above; leaf-blades long persistent. Leaf-sheath light green to light brown or straw-coloured, coriaceous, distinctly ribbed, smooth to finely scabrid, keeled. Ligule 0.2–1.0 mm, truncate, stiff, rim ciliate, undersides with matted stiff minute hairs. Leaf-blade 50–600 × 2.5–4.5 mm, folded to flat, or inrolled and c. 1 mm diameter, coriaceous, underside smooth, upper surface ribbed, covered with short prickle-teeth and sometimes short stiff hairs; margins ± thickened, smooth to sparsely scabrid, midrib scabrid near straight-sided, pungent tip. Culm 100–900 mm, internodes smooth, densely scabrid below panicle. Panicle 55–120 mm, lax or contracted; branches spreading or erect, sparsely to densely scabrid. Spikelets 6.5–14.5 mm, 2–5-flowered, greyish green to light greenish brown. Glumes subequal, 3-nerved, elliptic-lanceolate, acute to acuminate, often with minute fine hairs near tip, occasionally scabrid throughout, midnerve ciliate-scabrid especially on upper ½; lower 4.5–7.5 mm, upper 4.5–8.0 mm; margins ciliate. Lemma 4.5–9.0 mm, 5-nerved, elliptic- to oblong-lanceolate, subobtuse to subacute, scabrid above or occasionally throughout, midnerve with long fine hairs to ½ length, lateral nerves hairy near base; margins minutely ciliate. Palea 3.5–7.5 mm, keels rather stiffly ciliate-scabrid, interkeel with sparse minute hairs. Callus with loose web of long fine crinkled hairs. Rachilla 0.5–1.0 mm, glabrous to sparsely minutely pubescent; prolongation twice as long. Lodicules 0.5–2.0 mm, occasionally hair-tipped. Anthers 2.0–3.5 mm. Seed 2.0 × 0.5 mm
Similar taxa
Poa chathamica appears to be related to P. anceps, P. xenica Edgar et Connor, and an as yet unnamed hexaploid complex of plants currently included within Poa cita Edgar. From Poa anceps, P. chathamica differs by the upper surface of the leaf blades which are ribbed, and covered in fine prickle-teeth, by the spikelets which are 6.5–14.5 mm long, by the hexaploid (2n = 112) rather than diploid (2n = 28) chromosome number, and its geographic isolation on the Chatham Islands. From P. xenica it differs by hermaphrodite rather than dioecious habit, smaller panicles (120 cf. 250 mm in P. xenica), callus which bears loose crinkly hairs rather than being glabrous, and restriction to the Chatham Islands. Distinction from the swarding, widely creeping hexaploid forms of P. cita is less clear and requires further investigation. Currently the hexaploid forms of P. cita appear confined to the southern Cook Strait, North-West Nelson and northern Westland coastline.
Distribution
Endemic. New Zealand: Chatham Islands (all main islands).
Habitat
Coastal and inland. Widespread on sand dunes, within restiad peat bogs, rough pasture, along stream banks, river gorges, on rock outcrops and cliff faces and in boulder falls.
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.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – these interim threat classification statuses has not been assessed by the NZTCS panel.
- 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: IE, RR
Threats
It is threatened by habitat modification, stock grazing and competition from introduced plants such as marram grass.
Detailed taxonomy
Family
Poaceae
Synonyms
Poa anceps var. chathamica (Petrie) Zotov
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
September–January
Fruiting
January–February
Propagation technique
Easily grown from fresh seed and rooted pieces. Does best in full sun. However, in cultivation it rarely flowers.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
FAC: Facultative
Commonly occurs as either a hydrophyte or non-hydrophyte (non-wetlands).
Other information
Where To Buy
Not Commercially Available
Etymology
poa: Meadow grass
chathamica: From the Chatham Islands
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.
POACHA
Chromosome number
2n = 112
Previous conservation statuses
2017 | At Risk – Naturally Uncommon | Qualifiers: IE, RR
2012 | At Risk – Naturally Uncommon | Qualifiers: IE, RR
2009 | At Risk – Naturally Uncommon | Qualifiers: IE
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.