Pentapogon youngii
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Grasses
Detailed description
Slender tufts 0.3–1.3 m tall. Leaf-sheath papery, membranous, ribbed, glabrous or finely hairy, light green. Ligule 0.8–2.5 mm, truncate, ciliate to lacerate. Leaf-blade 120–350–(600) × 1–4 mm, stiff, flat or rolled, undersides smooth, upper ribbed, finely scabrid on ribs; margins finely scabrid, apex filiform, acute. Culm 0.4–1.15 m, nodes conspicuous, internodes usually smooth, sometimes scabrid near panicle. Panicle 70–160–(220) × 5–23 mm, linear-lanceolate, shortly and narrowly branched; rachis smooth, branches scabrid, pedicels slightly scabrid. Spikelets 4.5–7.5 mm, light green or purplish, crowded. Glumes 1-nerved, submembranous, elliptic-lanceolate, acute, scabrid, keel scabrid. Lemma (4)–5–6 mm, = glumes, scabrid, elliptic-lanceolate, apex denticulate; awn usually present, (0.5)–1–3 mm, straight, occasionally overtopping lemma apex. Callus hairs fine, covering (¼)-½ lemma length. Rachilla prolongation 1.5–2.5 mm, surmounted by dense hair-tuft 2–3.5 mm. Anthers penicillate.
Similar taxa
The narrow, cylindrical panicle places Pentapogon youngii near Pentapogon avenoides, P. quadrisetus, and P. lacustris. From these species it differs by the callus hairs extending for ½ the lemma length, and by the conspicuous hair tuft of the rachilla prolongation reaching the top of the lemma, or almost so. The lemma and rachilla prolongation characters place P. youngii close to P. aucklandicus from which it differs by the linear-lanceolate panicle, lemma 4–6 mm long, and by the straight awn rarely projecting beyond the glumes. In some plants the callus hairs are reduced, but in these cases the short awn and penicillate anthers are distinctive.
Distribution
Endemic. South Island only, where it is known from scattered sites from lake Sylvester (North West Nelson) south to Otago.
Habitat
Lowland to alpine. In forest clearings, tussock grassland, shrubland, boulderfield, on shaded bluffs, and along lake margins.
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: Sp, DPS, DPT
Threats
Naturally uncommon and of sporadic occurrence. In some lowland locations it may be threatened by grassland weeds.
Detailed taxonomy
Family
Poaceae
Synonyms
Agrostis youngii Hook.f., Calamagrostis youngii (Hook.f.) Petrie, Calamagrostis petriei Hack., Deyeuxia petriei (Hack.) Cheeseman, Calamagrostis youngii var. petriei (Hack.) Petrie, Deyeuxia youngii var. petriei (Hack.) Cheeseman,
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
October–February
Fruiting
October–March
Propagation technique
Difficult. Dislikes humid climates.Can be grown from the division of whole plants and fresh seed but plants tend to be short-lived.
Other information
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.
PENYOU
Chromosome number
2n = 28
Previous conservation statuses
2017 | At Risk – Naturally Uncommon | Qualifiers: DP, Sp
2012 | At Risk – Naturally Uncommon | Qualifiers: Sp
2009 | At Risk – Naturally Uncommon
2004 | Sparse
Referencing and citations
References and further reading
de Lange PJ, Schmid LMH. 2022. New combinations in Pentapogon for Aotearoa / New Zealand taxa earlier placed in Deyeuxia (Poaceae). Ukrainian Botanical Journal 79(2): 73–76.
Edgar E, Connor HE. 2000. Flora of New Zealand. Vol. V. Grasses. Manaaki Whenua Press, Christchurch, NZ. 650 p.
Attribution
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.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Pentapogon youngii Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/pentapogon-youngii/ (Date website was queried)