The New Zealand Plant Conservation Network

Species

Poa chathamica

Etymology

Poa: meadow grass
chathamica: From the Chatham Islands

Common Name(s)

Chatham Islands Poa

Current Conservation Status

2012 - At Risk - Naturally Uncommon

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2009 - At Risk - Naturally Uncommon
2004 - Range Restricted

Qualifiers

2012 - IE, RR
2009 - IE

Authority

Poa chathamica Petrie

Family

Poaceae

Flora Category

Vascular - Native

NVS Species Code

POACHA

Structural Class

Grasses

Synonyms

Poa anceps var. chathamica (Petrie) Zotov

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.

Features

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

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 Cooks Strait, North-West Nelson and northern Westland coastline.

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.

Threats

It is threatened by habitat modification, stock grazing and competition from introduced plants such as marram grass.

Chromosome No.

2n = 112

Endemic Taxon

Yes

Endemic Genus

No

Endemic Family

No

This page last updated on 7 Jan 2014