Schoenus vacillans
Biostatus
Native – Endemic taxon
Interim conservation status
Please note, conservation statuses are often proposed by authors of newly described taxa when they are published between NZTCS assessment periods. If such proposed conservation statuses are consistent with the criteria of the NZTCS, they are presented here as ‘interim’ statuses in accordance with the NZTCS manual, whilst acknowledging that they have not been formally assessed by the NZTCS panel.
2024 | Threatened – Nationally Critical | Qualifiers: DP | Interim | Shepherd, LD, Ford, M, & Perrie, LR. (2024)
Category
Vascular
Structural class
Sedges
Detailed description
Tufted perennial. Culms erect, flaccid, ± terete, striate, glabrous but sometimes scabrid distally on involucral bracts, 100–390 (– 500) mm long (inc. inflorescence), 0.4– 1.0 mm diameter, 2–4 (– 8) nodes. Leaves with blade 40–135 (– 200) mm long; sheath wine-red, striate, ± shining; mouth glabrous; ligule ± present or absent . Inflorescence of 4–6(– 8) nodes, 50–250 mm long, 40–73% of culm length; 1–8 spikelets per node, in diffuse clusters; proximal involucral bract 35–110 (– 160) mm long. Spikelets sessile or stalked singly, rarely in stalked sub-clusters of 2; (1? –) 2 (– 3?) flowered, 3.3–4.8 mm long. Glumes (4 –) 5–6, usually light to medium brown with hyaline margin, rarely dark red brown, and usually with prominent pale midvein that occasionally has a green centre; midvein usually scabrous. Fertile glumes 2.6–3.4 mm long. Hypogynous bristles 4–6, much shorter than nutlet. Stamens 3. Nutlets trigronous, obovoid to subglobose, 1.0– 1.4 mm long, 0.6–0.8 mm wide, 3-ribbed, reticulate-pitted, white, with prominent apical beak.
Similar taxa
Schoenus vacillans is easy to recognise, in the field, the culms of Schoenus vacillans seem to be a darker green and more flaccid than the lighter green and more erect culms of S. apogon.
The inflorescences of S. vacillans are diffuse, being comparatively long (more than 40% of the total culm length), with 4 to 6 nodes (rarely up to 8), and only up to 8 spikelets per node. Within an inflorescence node, the spikelets are sessile or singly stalked, and only rarely in stalked pairs. By contrast, S. apogon has shorter inflorescences (usually less than 32% of the total culm length), usually only 1 to 3 nodes, and up to 40 spikelets per node. The spikelets can be in stalked sub-clusters of up to 15. The spikelet clusters of at least the distal inflorescence nodes appear hemispherical, an appearance that is entirely lacking in S. vacillans.
The glumes of Schoenus vacillans are light to medium brown with hyaline margins, and usually with a prominent cream midvein (around the keel). In S. apogon, the glumes are usually dark red brown with hyaline margins. The midvein area can be paler, and is occasionally narrowly cream, but then only proximally. At a distance, the inflorescence ‘heads’ of S. apogon usually appear much darker than those of S. vacillans.
Furthermore, the nutlets of Schoenus vacillans have a prominent apical beak that is short or absent in S. apogon. In S. vacillans, the hypogynous bristles are much shorter than the nut they surround, whereas they are similar in length or longer in S. apogon.
Distribution
North Island: Northland (Taipa, Warawara, Waimā, Tutamoe), Auckland (Coromandel, Te Aroha), Taranaki (Whitecliffs), central North (Ruapehu, Ohakune).
Habitat
Schoenus vacillans appears to prefer shady, often damp sites on the sides of gullies, creeks, and banks. Some records are from recently-disturbed sites such as old slips. In contrast to, S. apogon which occurs in open, grassland-like habitats including lawns and pasture, on banks or terraces at forest margins, and in gumland.
Most collection sites are from mountain ranges (including the Kaimai Range, Coromandel Range, Tutamoe Range, Waima Forest and Warawara Forest), but a specimen from Taipa was collected at an elevation of only 50 m (AK 212198).
Threats
Few of the records have been made within the last 30 years, and known populations are small. For example, a recent survey at Waima Forest by Marley Ford found 6 populations but most contained only 1–2 plants and the largest population, which was on a large slip, comprised only approximately 30 plants. The other five populations were found along tracks and smaller disturbed areas. Only a single site is known at present from the Coromandel Range, with some 40 plants in regenerating forest along an eroding 40 m stretch of a popular walking track. The apparent preference of S. vacillans for regenerating slip sites may complicate its in situ conservation, with existing plants at risk from further slips or from the loss of habitat with regeneration and succession. With fewer than 250 mature plants currently known, Schoenus vacillans meets the criteria of Nationally Critical, albeit with the qualifier Data Poor (de Lange et al. 2018). It is likely that further populations of S. vacillans exist in remote, difficult to access areas, such as the steep gullies of the Coromandel and Kaimai Ranges. We hope that our reinstatement of S. vacillans as a distinct species prompts searches for previously recorded populations as well as new populations
Detailed taxonomy
Genus
Family
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Other information
Etymology
schoenus: Rush
Previous conservation status
Please note, conservation statuses are often proposed by authors of newly described taxa when they are published between NZTCS assessment periods. If such proposed conservation statuses are consistent with the criteria of the NZTCS, they are presented here as ‘interim’ statuses in accordance with the NZTCS manual, whilst acknowledging that they have not been formally assessed by the NZTCS panel.
2023 | Not Evaluated
Referencing and citations
References and further reading
de Lange PJ, Rolfe JR, Barkla JW, Courtney SP, Champion PD, Perrie LR, Beadel SM, Ford KA, Breitwieser I, Schönberger I, et al. 2018. Conservation status of New Zealand indigenous plants, 2017. New Zealand Threat Classification Series 22. Wellington: Department of Conservation.
Shepherd, LD, Ford, M, & Perrie, LR. 2024. Genetic and morphological analyses support the reinstatement of Schoenus vacillans (Cyperaceae) as distinct from S. apogon. New Zealand Journal of Botany, 1-16.
Attribution
Fact sheet prepared by Marley Ford (24 August 2024). Brief description, Distribution, Habitat, Features, and Similar taxa sections copied and adapted from Shepherd et al. (2024).
NZPCN Fact Sheet citation
Please cite as: Ford, M. (Year at time of access): Schoenus vacillans Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/schoenus-vacillans/ (Date website was queried)