Senecio quadridentatus

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Species

Senecio quadridentatus

Etymology

Senecio: From the Latin senex 'old man' (probably referring to the bearded seeds)

Common Name(s)

cotton fireweed, white fireweed, pahokoraka

Current Threat Status

2012 - Not Threatened

Previous Threat Status

2009 - Not Threatened
2004 - Not Threatened

Authority

Senecio quadridentatus Labill.

Family

Asteraceae

Flora Category

Vascular - Native

Synonyms

Erechtites quadridentata (Labill.) DC.

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

Features

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 altitudes 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.

Flowering

October - March

Main Flower Colour

Yellow

Other Flower Colour

Black

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.

Threats

Not Threatened

Chromosome No.

2n = 40

Endemic Taxon

No

Endemic Genus

No

Endemic Family

No

Where To Buy

Not commercially available.

Taxonomic notes

Unpublished Molecular evidence (nrDNA ITS sequences) held by University of Auckland place this species as sister to S. marotiri and S. dunedinensis.

 

References and further reading

Thompson, I.R. 2004: Taxonomic studies of Australian Senecio (Asteraceae): 1. The disciform species. Muelleria 19: 101-214.

This page last updated on 11 Aug 2014

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