Senecio quadridentatus
Common names
cotton fireweed, white fireweed, pahokoraka
Biostatus
Native
Category
Vascular
Structural class
Herbs - Dicotyledonous composites
Flower colours
Yellow
Detailed description
Short-lived, usually much branched, perennial herb up to 1 m tall. Stems erect, moderately to densely covered in appressed-cottony hairs. Mid stem leaves more or less evenly spaced and sized., linear to narrow linear, 80-220 mm long, length:width ratio (l:w) 15-40 (or 7-10 if lobes present), mostly entire, rarely dissected or lobed, sometimes coarsely dentate to lobate; segments remote 1-3 per side and mainly in proximal half, spreading, triangular, base attenuate or occasionaly with small entire auricles, not amplexicaul; margin entire or with frequentminute denticulations, appearing entire due to revolute margin; upper surface hairs appressed-cobwebby becoming glabrescent; lower surface green or purple-green, moderately to densely woolly. Upper stem leaves similar; auricles more frequent. Unit Inflorescence usually of many capitula; total number of capitula per stem often 50-200; overtopping variable; mature lateral peduncles mostly 5-25 mm long. Calycular bracteoles of capitula 4-8, 1.0-3.0 mm long peduncle and margin of bracteoles cobwebby to woolly at anthesis, or glabrate; involucre 6.0-10.0 x 1.2-2.0 mm; involucral bracts 8-14, basally cobwebby or glabrate, with apex erect; stereomes (in dried material) more or less flat, green or partially purple, sometimes minutely black-tipped or purple in a zone 1 mm long below tip. Florets 18-50, c. 80% female; corolla-lobes triangular, not or hardly thickened apically; corolla of bisexual florets 6-9 mm long, 4-lobed; corolla-lobes of female florets 3, 0.1 mm long. Cypsela 2.2-3.5 mm long, subcylindric, narrow to and constricted below apex, usually with 2-3 rows of hairs in narrow grooves between broad ribs, sometimes glabrous.
Similar taxa
Seencio dunedinensis Belcher is similar and could be confused. Generally it is a smaller less heavily branched plant, with much wider dark green to purple-green glabrescent leaves. The involucral bracts are 4–6 mm rather than 6–10 mm long. Senecio quadridentatus tends to grow at lower elevations than S. dunedinensis but at times the two species are sympatric and some of the variation seen between both species may be due to hybridism.
Distribution
Indigenous. Three Kings, North, South, Stewart and Chatham Islands. Present in Australia
Habitat
Throughout from coastal to subalpine habitats. Always in recently distrubed ground
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 | Not Threatened | Qualifiers: SO
Detailed taxonomy
Family
Asteraceae
Synonyms
Erechtites quadridentata (Labill.) DC.
Taxonomic notes
Unpublished Molecular evidence (nrDNA ITS sequences) held by University of Auckland place this species as sister to S. marotiri and S. dunedinensis.
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
October–March
Fruiting
December–May
Propagation technique
Easy from fresh seed. The silvery white foliage can be quite attractive but this species is invasive. Prefers full sun.
Other information
Etymology
senecio: From the Latin senex ‘old man’ (probably referring to the bearded seeds)
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.
SENQUA
Chromosome number
2n = 40
Previous conservation statuses
2017 | Not Threatened | Qualifiers: SO
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Referencing and citations
References and further reading
Thompson IR. 2004. Taxonomic studies of Australian Senecio (Asteraceae): 1. The disciform species. Muelleria 19: 101–214.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (12 July 2005). Description based on Thompson (2004).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Senecio quadridentatus Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/senecio-quadridentatus/ (Date website was queried)