Simplicia laxa
Common names
simplicia
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Grasses
Simplified description
Feeble, inconspicuous mat-forming grass of shaded habitats. Plants rooting at nodes. Leaf sheaths hairy. Inflorescences inconspicuous, delicate, pyramidal; flowering branches hairy, basal branches usually reflexed and spreading. Spikelets one-flowered, bearing prominent hairy lemma and much reduced, minute scale-like glumes.
Flower colours
Green
Detailed description
Plants trailing forming thick sprawling mats or diffuse interconnected patches up to 0.6 m across. Culms 0.40–0.80 m long, green to pale green when fresh, wiry, decumbent, with the apices weakly erect, culm internodes 4–8, elongated, sparsely (sometimes densely) hairy, or glabrous; hairs weakly flexuous, patent up 0.18 mm long; internodes usually shorter than subtending leaf-sheaths. Culm-nodes conspicuously swollen when fresh, maroon-black to black (0.13–)0.18–0.30 mm long, rooting freely on contact with ground. Basal leaf-sheaths glossy light brown to amber, membranous, ribbed, abaxially (often copiously) pubescent on ribs (and usually on interstices), hairs 0.20–0.25(–0.30) mm long, patent to retrorse; mid stem and upper leaf-sheaths pale-green to green, membranous, ribbed, abaxially pubescent on ribs (and sometimes on interstices), hairs copious, 0.35–0.40 mm long patent, mostly straight, sometimes curved or weakly flexuous. Ligule 2.8–3.5–(10) mm, membranous, lanceolate, apex erose to very deeply lacerate; abaxially sparsely to copiously hairy; hairs 0.20–0.24 mm long. Leaf-blade (100)–160–(200) × (2.8)–3.0–(3.6) mm, green to dark green, flat, linear-lanceolate, finely ribbed; adaxial ribs finely pubescent, abaxially glabrous (sometimes sparsely hairy at leaf base; margins ± smooth, sometimes irregularly finely scabrid and sparsely hairy. Panicle (40)–100–( 150) mm long, linear to ± pyramidal, usually with basal branch or branch pair reflexed (often unevenly so); rachis glabrous, branches (20)–40–(60) mm long, finely, antrorsely hairy (hairs 0.20–0.25 mm long), binate, initially contracted but as inflorescences mature, spreading to reflexed, devoid of spikelets in lower half; pedicels appressed to branchlets, 1.00–1.06 mm long, finely pubescent. Spikelets 2.8–3.2 mm, 1-flowered, lanceolate, light green. Glumes pale green (± hyaline), glabrous, broadly ovate-lanceolate to ovate, acute, 1-nerved, nerve extending beyond apex as a minute mucro, lower glume margins entire (sometimes with apex erose), ciliate towards apex, upper glume margins usually erose (sometimes subentire), ciliate; lower glume 0.5–0.8 mm, upper glume 0.75–1.0–(1.2) mm. Lemma 2.8–3.2–(3.4) mm, light green to grey-green (sometimes purple-green), ± evenly, densely pubescent, lanceolate, acute, apex mucronate (mucro 0.10–0.25 mm long), 3–(5)-nerved (nerves obscured by hairs); lemma hairs antrorse appressed, sericeous, 0.12–0.13 mm long. Palea 2.4–2.8 mm, lanceolate, pale green to green, pubescent, 1–2-nerved, (nerves obscured by hairs). Rachilla prolongation 1.25–1.30 mm, narrowly lanceolate, hyaline, margins minutely ciliate. Stamens 3. Filaments 0.20–0.25 mm long, hyaline. Anthers 0.30–0.45 mm, yellow. Ovary narrowly ovoid to weakly trigonous 1.0–1.25 mm long, dark green, ± glabrous (basal portion sometimes minutely ciliate); styles apical, 1.10–1.25 mm, hyaline; stigmas plumose, white. Caryopsis 1.4–1.5 mm long, laterally compressed, orange-brown when mature.
Similar taxa
Allied to Simplicia felix from which it is distinguished by the mid-stem and upper stem leaf sheaths finely ribbed and copiously hairy; by the hairy adaxial leaf-blade ribs; by the antrorsely hairy inflorescence branches, longer pedicels 1.00–1.06 mm long and pubescent lemma (see de Lange et al. 2016). Simplicia felix and S. laxa differ from S. buchananii by the decumbent rather than tufted grwoth habit, spreading to weakly ascendent rather thabn erect culms, by the nodes which root freely (plants thus forming nterconnected widely sprawling clonal patches) and by the linear to pyramidal, binate inflorescences, whose basal branch or branches are reflexed, and devoid of spikelets from lower half or so (see de Lange et al. 2016).
Distribution
Endemic. South Island—Otago with one site at Honeycomb Cave, Karamea (de Lange et al. 2016).
Habitat
Simplicia laxa has been recorded from coastal to subalpine situations on base-rich rocks such as limestone, schist and basalt. All current populations grow on rock ledges, within crevices, overhangs and at cave entrances. It is suspected that the current habitats of Simplicia laxa are refugia, and that the species was once found in forested habitats (see de Lange et al. 2016).
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 | Threatened – Nationally Critical | Qualifiers: Sp, DPR, DPS, DPT, RR
Threats
Currently known from < 15 populations. Several of these are in decline, and very few are substantial in size. Many occur on private land without direct conservation management or in places subject to ongoing habitat deterioration through invasive weed pressure and habitat loss (for more information see de Lange et al. 2016).
Detailed taxonomy
Genus
Family
Synonyms
Simplicia laxa Kirk var. laxa
Taxonomic notes
North Island Simplicia occurrences discussed by Ogle (2010) and Smissen et al. (2011) together with one North Otago population now belong to a third species S. felix (de Lange et al. 2016). As far as is known Simplicia laxa is not present in the North Island, the specimens Kirk collected from the Wairarapa belong to S. felix (de Lange 2016; de Lange et al. 2016).
Endemic taxon
Yes
Endemic genus
Yes
Endemic family
No
Ecology
Flowering
November–March
Fruiting
January–May
Propagation technique
Easy from rooted pieces. Can be grown from node cuttings. Often difficult to maintain in cultivation, and short-lived. It does best in a dry shady site, and should be planted in a free draining, lime-enriched soil.
Other information
Plant of the Month
This plant has been featured as a Plant of the Month – see Trilepidea: NZPCN newsletter for January 2010 for the full story.
Etymology
laxa: Slack, loose
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.
SIMLAX
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 | Threatened – Nationally Critical | Qualifiers: CD, RR, Sp
2012 | Threatened – Nationally Critical | Qualifiers: CD, Sp
2009 | Threatened – Nationally Critical | Qualifiers: CD, Sp
2004 | Threatened – Nationally Endangered
Regional conservation statuses
Otago: 2025 | Regionally Threatened – Regionally Critical | Qualifiers: DPS, DPT, NR, NStr, PF, RF, Sp, TL
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 “Conservation Status of Indigenous Vascular Plants in Otago, 2025” Jarvie S et al. (2025) report.
Referencing and citations
References and further reading
de Lange PJ. 2016. When labels get mixed – lessons to be learned from a study of the Thomas Kirk ‘herbarium’ and historical Simplicia collections. Trilepidea 152: 1–11.
de Lange PJ, Heenan PB, Norton DA, Rolfe JR, Sawyer JWD. 2010. Threatened Plants of New Zealand. Canterbury University Press, Christchurch. 471 p.
de Lange PJ, Rolfe JR, Silbery T. 2014. Seen but unseen – rediscovering Simplicia laxa in the southern North Island. Trilepidea 124: 5–9.
de Lange PJ, Smissen RD, Rolfe JR, Ogle CC. 2016. Systematics of Simplicia Kirk (Poaceae: Agrostidinae)—an endemic, threatened New Zealand grass genus. PhytoKeys 75: 119–144. https://doi.org/10.3897/phytokeys.75.10328
Edgar E, Connor HE. 2000. Flora of New Zealand. Vol. V. Grasses. Manaaki Whenua Press, Christchurch, NZ. 650 p.
Kirk T. 1897. Description of a New Genus of Gramineae. Transactions of the New Zealand Institute 29: 497.
Ogle CC. 2010. Rediscovery of a rare species of grass in the genus Simplicia in the North Island. Wellington Botanical Society Bulletin 52: 38–46.
Smissen RD, de Lange PJ, Thorsen MJ, Ogle CC. 2011. Species delimitation and conservation genetics in the rare New Zealand endemic grass genus Simplicia. New Zealand Journal of Botany 49: 187–199.
Zotov VD. 1971. Simplicia T. Kirk (Gramineae). New Zealand Journal of Botany 9: 539-544.
Attribution
Fact Sheet prepared for NZPCN by P.J. de Lange (1 November 2009). Description from de Lange et al. (2016) For more information see Kirk (1897), Zotov (1971), Edgar & Connor (2000), and de Lange et al (2010).
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): Simplicia laxa Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/simplicia-laxa/ (Date website was queried)