Poa senex
Common names
Old Man poa
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Grasses
Detailed description
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.
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
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: DPS, DPT, RR
Threats
Not Threatened. Listed because it is a Naturally Uncommon, Biologically Sparse, Range Restricted Alpine endemic.
Detailed taxonomy
Family
Synonyms
None (first described in 1986)
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
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.
Other information
Where To Buy
Not commercially available.
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.
POASEN
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: DP, RR
2009 | At Risk – Naturally Uncommon | Qualifiers: SP, RR
2004 | Range Restricted
Regional conservation statuses
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Otago conservation status information is sourced from the “Regional conservation status of indigenous vascular plants in Otago” Jarvie S et al. (2024) report.
Otago: 2024 | Regionally Data Deficient | Qualifiers: TL
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.