Chatham Islands Poa
Poa anceps var. chathamica (Petrie) Zotov
Vascular – Native
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.
2n = 112
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). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By 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.
2012 | At Risk – Naturally Uncommon | Qualifiers: IE, RR
Previous conservation statuses
2009 | At Risk – Naturally Uncommon | Qualifiers: IE
2004 | Range Restricted
Endemic. New Zealand: Chatham Islands (all main islands).
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.
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 50.0-600.0 × 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
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 Cooks Strait, North-West Nelson and northern Westland coastline.
September - January
January - February
Easily grown from fresh seed and rooted pieces. Does best in full sun. However, in cultivation it rarely flowers.
It is threatened by habitat modification, stock grazing and competition from introduced plants such as marram grass.
poa: Meadow grass
chathamica: From the Chatham Islands
Where To Buy
Not Commercially Available
Description modified from Edgar and Connor (2000).
References and further reading
Edgar, E.; Connor, H.E. 2000: Flora of New Zealand. Vol. V. Grasses. Christchurch, Manaaki Whenua Press. 650 pp. As currently circumscribed Poa chathamica is a very variable species.