Senecio sterquilinus
Common name
Guano groundsel
Synonyms
Senecio lautus var. á macrocephalus Hook.f.
Family
Asteraceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Dicotyledonous Herbs - Composites
Chromosome number
2n = 40
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 | At Risk – Relict | Qualifiers: RR
Previous conservation statuses
2009 | At Risk – Relict | Qualifiers: RR
2004 | Range Restricted
Distribution
Endemic. North, South and Chatham Islands. Known from Stack H (Mokohinau islands group), Hawkes Bay (extinct), Matiu/Somes, Makaro/Ward, Brothers and Stephens islands in the Cook Strait. Also on the West Coast from Cape Foulwind south to Point Elizabeth. Around Wellington Harbour this species is occasionally seen at Petone Beach and Evans Bay. On the Chatham Islands it has been recently (2006) collected from the Forty Fours, Sisters and Western Reef
Habitat
A strictly coastal species usually found growing in the vicinity of sea bird nesting grounds or seal haul outs. Often found growing out of thick guano deposits on sparsely vegetated rock stacks dominated by sea birds.
Features
Annual to short-lived perennial, subsucculent, fleshy to succulent herb, forming densely branched, somewhat sprawling plants up to 0.6 x 0.6 m. Basal stem woody, purple-red or purple, glabrous, rest of stem purple, purple-green or green, sparsely covered with cobwebby hairs. Leaves fleshy, subsucculent to succulent, sparsely to moderately cobweb-hairy, especially on the undersides, often more densely so on emergent leaves, becoming glabrate to glabrous, cuneately narrowed to seed, amplexicaul, 30-200 x 10-80 mm, dark green and glossy above, paler green or purple-green below, elliptic to ovate or rhomboid, usually pinnately lobed to pinnatisect with very broad pinnately lobed or deeply toothed segments, rarely crenate to entire. Upper most leaves similar but smaller, usually less divided, base shortly and broadly cuneate, amplexicaul. Supplementary bracts and calycular bracteoles 9-30, 1.5-8 mm long. Involucral bracts 13-21, glabrescent to glabrous, 6-12 mm long. Ray florests 13-28; ligules dark yellow, closely spaced or overlapping, 3-10 mm long. Disc yellow 10-25 mm diameter. Cypsela 2.5-3.0 mm long, dark brown, dark purple-brown to black-brown, narrowly oblong to narrowly oblong-elliptic, scarcely narrowed at apex, base cuneate; ribs broad and rounded; grooves narrow to u-shaped; hairs retrorse in 4-10 rows filling grooves, often obscuring ribs as well. Pappus 5-6 mm long, white, caducous.
Similar taxa
Senecio lautus Willd. subsp. lautus is frequently sympatric with S. sterquilinus and could be potentially be confused with it. From S. sterquilinus, S. lautus subsp. lautus differs by its usually smaller growth habit, finer more divided leaves, and fewer involucral bracts (up to 15, mostly 10-13 cf. up to 25, mostly 18-21), and somewhat smaller seeds (2.2-3.0 cf. 2.5-3.0). Both species are clearly closely related, have the same chromosome number (2n = 40) and putative hybrids have been collected. On the Chatham Islands S. sterquilinus has been found growing with the endemic S. radiolatus F.Muell. subsp. radiolatus from which its distinction can be difficult, particularly with glabrescent forms of S. radiolatus. From that species S. sterquilinus differs by its smaller, more widely spreading habit, very fleshy/succulent glabrescent leaves which lack lanate hairs, greater number of ray florets 13-28 cf. 10-20.
Flowering
July - June
Flower colours
Yellow
Fruiting
July - June
Propagation technique
Easy from fresh seed. A strict anuual which thrives in very fertile (high N, P, K) damp soil in full sun. This species, along with S. radiolatus F.Muell was trialled in annual flower beds in parts of Lower Hutt during 1991, it was very succesful and popular with the public. The large, yellow flower heads often completely cover the plant.
Threats
A vulnerable herb of very restricted and probably relict distribution. Abundant at most of its known localities and seemingly dependant on sea bird guano to thrive. This makes it very vulnerable to any decline in nesting/roosting sea birds.
Etymology
senecio: From the Latin senex ‘old man’ (probably referring to the bearded seeds)
Where To Buy
Not commercially available
Attribution
Fact Sheet prepared for NZPCN by P.J. de Lange 1 November 2008. Description based on Webb et al. (1988) supplemented by observations obtained from fresh specimens and herbarium material
References and further reading
Webb CJ, Sykes WR, Garnock-Jones PJ 1988. Flora of New Zealand. Vol. IV. Botany Division, DSIR, Christchurch
Citation
Please cite as: de Lange, P.J. (Year at time of access): Senecio sterquilinus Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/senecio-sterquilinus/ (Date website was queried)