Poa senex
Common name
Old Man 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
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.
POASEN
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). 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: DP, RR
Previous conservation statuses
2009 | At Risk – Naturally Uncommon | Qualifiers: SP, RR
2004 | Range Restricted
Distribution
Endemic. New Zealand: South Island (Otago and Southland (Pisa Range, Old Man Range, Old Woman Range, Crown Range, Harris Mountains, Eyre Mountains).
Habitat
Alpine. On snow banks, in wet depressions, flushes, streamsides and other damp ground within alpine herbfield
Features
Diminutive, tufted, stoloniferous, glabrescent to glabrous, brownish green perennial grass, up to -250 mm tall, culms overtopping leaves; branching extravaginal; leaf-blades persistent. Leaf-sheath membranous, glabrous, ribbed, keeled. Ligule 0.5-1.5 mm, entire, tapered, glabrous throughout. Leaf-blade 10-35 × 1-2 mm, flat or folded, subcoriaceous, smooth, but midrib scabrid near curved tip; margins finely scabrid. Culm 30-200 mm, very slender, erect or geniculate at base, internodes glabrous. Panicle 10-30, ± open or contracted, with few, ovate spikelets; rachis, branches and pedicels slender with sparse, scattered prickle-teeth. Spikelets 2.0-3.5 mm, 2-3-flowered, light green, tinged purple. Glumes unequal, submembranous with hyaline margins, a few prickle-teeth on midnerve near tip; lower 1.5-2 mm, 1-nerved, narrow-lanceolate, acute, upper 2.0-2.5 mm, (1-)3-nerved, elliptic-oblong, subobtuse to obtuse. Lemma 2.0-2.5 mm, 5-nerved, elliptic-ovate, obtuse, glabrous, but midnerve with short crinkled hairs to c.½ length and sparsely prickle-toothed near tip, lateral nerves with a few hairs near base. Palea 1.5-1.8 mm, keels minutely scabrid, interkeel glabrous. Callus with a few wispy hairs. Rachilla c.0.5 mm, glabrous. Lodicules c.0.1 mm. Anthers 0.3-0.4 mm. Ovary 0.4-0.5 mm; stigma-styles 0.8-1 mm. Seeds c.1.0 × 0.5 mm
Similar taxa
Allied to P. sublimis Edgar and P. incrassata Petrie, two other species which are diminutive, small-anthered, alpines colonising damp ground. From these species Poa senex differs in having hairs on the lemma nerves. From P. sublimis it is further distinguished by the more contracted panicle with firmer branchlets, and from P. incrassata by the wider leaves, and by the flat, not hooded, lemma tip and glabrous, not papillose, lemma internerves.
Flowering
November - December
Fruiting
December - March
Propagation technique
Difficult. Can be grown from fresh seed and rooted pieces in an alpine house. Will not flower or thrive in warm or humid climates. Intolerant of drying out.
Threats
Not Threatened. Listed because it is a Naturally Uncommon, Biologically Sparse, Range Restricted Alpine endemic.
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, H.E. 2000: Flora of New Zealand. Vol. V. Grasses. Christchurch, Manaaki Whenua Press. 650 pp.