Senecio minimus
Common name
fireweed
Synonyms
Senecio heterophylla Colenso, Erechtites minima (Poir.) DC. var. minima, Erechtites minima var. angustata Allan, Erechtites minima var. heterophylla (Colenso) Allan, Erechtites pumila DC.
Family
Asteraceae
Flora category
Vascular – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Herbs - Dicotyledonous composites
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.
SENMIN
Chromosome number
2n = 60
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley.
2012 | Not Threatened
Previous conservation statuses
2009 | Not Threatened
2004 | Not Threatened
Distribution
Indigenous. Three Kings, North, South, Stewart and Chatham Islands. Present in Australia.
Habitat
A weedy species of disturbed ground. Predominantly coastal to montane but occasionally extending into subalpine habitats. Most commonly associated with forest margins.
Features
Short-lived perennial to annual herb up to 2 m tall. Stems erect, green to dark purple, sparsely and minutely coarse-hairy below mid stem, becoming glabrous above. Mid stem leaves more or less evenly spaced and sized, 80-250 mm long, length:width ratio (l:w) 3-6, oblanceolate to narrow-elliptic, rarely broadly elliptic, not dissected often shallowly crenate; base auriculate, semi-amplexicaul; margin crowded-denticulate; upper surface dark green to greyish-green, glabrous or sparsely scabridulous; lower surface green or purple, sparsely cobbwebby. Upper most leaves narrowly elliptic, occasionally linear or narrow-lanceolate, l:w 3-10, often widest at auricles. Unit Inflorescences of many capitula; total number of capitula per stem often several hundred; overtopping absent or slight; mature lateral peduncles mostly 5-10 mm long. Capitula: calycular bracteoles 3-5, 1.0-2.0 mm long; peduncles mostly 5-10 mm long.; peduncle and margin of bracteoles more or less glabrous to lightly cobbwebby at anthesis; involucre 4.0-6.5 x 1.0-1.5 mm, involucral bracts 7-10, glabrous; stereomes (in dried material) mor eor less flat, green with black tips. Florets 12-25, c. 80% female; corolla lobes triangular, thickened apically; corolla of bisexual florets 4.5-6.0 mm long, 4-5-lobed; corolla lobes of female florets 3-4, 0.2-0.3 mm long. Cypsela 1.6-2.5 mm long, narrow obloid, sometimes slightly angular, dull brown or dark red-brown, somewhat lustrous with papillose hairs in lines. Pappus 5-6 mm long.
Similar taxa
Senecio minimus is most similar to S. kermadecensis which, as the name suggests, is endemic to the Kermadec Island group. That species differs from S. minimus by its bright green leaves, elliptic rather than mostly narrow-elliptic to narrow-lanceolate mid stem leaves, fewer involucral bracts (5-8 cf. 7-10 in S. minimus), and by the cypsela (seeds) which have hairs within the grooves between the ribs, rather than on the ribs. Some Northland, Auckland and Coromandel plants of S.minimus have broader elliptic leves and so approach S. kermadecensis but these plants match S. minimus with respect to involucral bract number and the distribution of hairs on the cypsela. This race of S. minimus deserves further critical study (see comments by de Lange & Rolfe 2010).
Flowering
Throughout the year but peaking in summer
Fruiting
Throughout the year but most common in late summer to early autumn
Propagation technique
Easy from fresh seed but can become invasive. Has little horticultural merit.
Etymology
senecio: From the Latin senex ‘old man’ (probably referring to the bearded seeds)
minimus: Smallest (rather a misnomer)
Where To Buy
Not commercially available.
Taxonomic Notes
In New Zealand two races are recognisable one, which is widespread is a robust plant with thicker, narrower leaves and usually distinctly hairy, green to grey-green stems. This race matches the type of S. minimus (see Drury 1974). The other is smaller, and has consistently dark purple stems and leaf undersides, and much broader glabrate leaves. This second race first appeared in Northland about 50 years ago and is actively spreading south. A collection of this race from the Poor Knights Islands was treated by Drury (1974) as S. kermadecensis which it approaches only in its leaf shape. Both races key out to S. minimus using Australian treatments.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 28 July 2007. Description by P.J. de Lange based on Webb et al. (1988) and observations obtained from fresh plants and herbarium specimens.
References and further reading
de Lange, P.J.; Rolfe, J.R. 2010: New Zealand Indigenous Vascular Plant Checklist. Wellington, New Zealand Plant Conservation Network. 164pp.
Drury, D.G. 1974: Illustrated and annotated key to the erechtitoid senecios in New Zealand (Senecioneae-Compositae) with a description of Senecio diaschides. N.Z. Journal of Botany 12(4): 513–540.
Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J. 1988: Flora of New Zealand Vol. IV. DSIR, Christchurch.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Senecio minimus Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/senecio-minimus/ (Date website was queried)