Classification
Class
Magnoliopsida Brongn.
Order
Asterales Link
Family
Compositae Giseke
Genus
Senecio L.
 Nomenclature
Scientific Name:
Senecio esperensis (Sykes) de Lange in de Lange et al., 53 (2015)
Synonymy:
  • ≡ Senecio lautus var. esperensis Sykes, New Zealand J. Bot. 9: 533-536 (1971)
  • ≡ Senecio lautus subsp. esperensis (Sykes) de Lange in de Lange et al., Threat. Pl. New Zealand 437 (2010)
Holotype. ‘Kermadec Islands, L’Esperance; scoria pockets inside crater’, W. R. Sykes s.n., 19 Jul. 1969, (CHR 193800!).
 Description

Annual, succulent, herb up to (0.16–)0.35–0.90(–1.0) m tall. Stem stout, up to 20–30 mm diameter, ± terete to somewhat angular, erect, simple, only rarely branching from base, glabrous, dark green occasionally dark purple to purple-black; basal portion fibrous to somewhat woody, much scarred with leaf base remnants. Cotyledons 10–25 × 5–15 mm, ovate, petioles 8–12 mm long. Leaves glabrous, succulent, adaxially dark glossy green, abaxially paler. Lower cauline leaves with indistinct petioles 10–30 × 2–3 mm, winged, decurrent on stem; lamina 40–75 × 10–38 mm, oblong-spathulate, lanceolate to rhomboidal, irregularly and coarsely serrated with teeth up to 10 mm long, apex acute. Mid-cauline leaves gradually decreasing in size up the stem, lowermost sessile and auriculate, then amplexicaul; lamina 50–180 × 20–65 mm, oblong-spathulate to lanceolate, irregularly serrate to lobulate with teeth up to 5 mm long but never deeply pinnatifid, apex subacute to obtuse. Upper cauline leaves gradually decreasing in size up the stem, initially amplexicaul, lamina 10–130 × 8–30 mm, broadly lanceolate to lanceolate, with uppermost auriculate, lamina 7–20 × 3–8 mm, linear-lanceolate to linear; winged, with bases decurrent with stem, margins irregularly and unequally serrated, teeth up to 5 mm deep, apex subacute to acute. Inflorescence terminal, often partially obscured within foliage, much branched. Capitula numerous, usually densely clustered, broadly cylindrical, 7.0–7.5 × 5.0–5.8 mm; peduncles ± terete to square in cross-section, deeply ribbed, succulent, glabrous. Supplementary bracts 3–5, widely spaced, not or scarcely imbricate, 3.0–6.5 mm long, lanceolate to linear-lanceolate, succulent, glabrous, dark green, base amplexicaul in lowermost bracts, auriculate in uppermost, margin sparingly to prominently toothed 3–4 × each side, apex acute to acuminate. Calycular bracteoles subtending the involucre 3–5, imbricate, appressed when fresh, patent when dry, 1.2–3.8 mm long, broadly lanceolate, succulent, ± glabrous, dark green, base decurrent with peduncle, margin irregularly sinuate, weakly toothed or entire, apex maroon and crested with fine white, arachnoid trichomes. Involucral bracts (8–)10(–13), broadly lanceolate or ovate-lanceolate, (5.2–)5.6(–7.0) × (2.1–)2.9(–3.2) mm, longer than ray-florets, ± glabrous, dark green; mid-vein distinct, very dark green when fresh, drying brown-green; margin hyaline-green, broadening to apex, basally entire, sometimes wholly entire, but usually becoming distinctly scarious towards apex; apices tapering to acuminate, apex rounded to acute, crested with fine, white, arachnoid trichomes, dark green or tinged maroon. Ray florets ♀, (7.0–)7.8(–9.0), unequally disposed around disc; ligules spathulate, (2.0–)3.1(–5.0) × 1.5–1.8(–2.0) mm, basal unexposed limb green to dark yellow-green funneliform, upper exposed portion sulphur yellow, flattened; apex often recurved, blunt-ended or incised up to three times. Disc 4.5–6.0 mm diameter, disc florets ☿, similar to ray florets but larger, (12–)16(–20), 4.0–4.3(–4.6) mm long, dark sulphur yellow. Cypsela oblong-elliptic, slightly narrowed at apex, 2.0–2.5(–3.0) × 0.6–0.8(–1.0) mm; base cuneate; ribs 6–8, fawn-coloured, broad, glabrous; grooves between ribs mostly broad, U-shaped, sparsely hairy; trichomes mostly retrorse, 0.1–0.3 mm long; surface brown. Pappus caducous, minutely barbellate, 3.0–3.5 mm long.

[Reproduced from de Lange et al. (2014, New Zealand J. Bot. 53: 131–138) with permission from The Royal Society of New Zealand.]

 Biostatus
Indigenous (Endemic)
 Bibliography
de Lange, P.J.; Heenan, P.B.; Norton, D.A.; Rolfe, J.R.; Sawyer, J. 2010: Threatened plants of New Zealand. Canterbury University Press, Christchurch.
de Lange, P.J.; Liew, C.S.; Rolfe, J.R.; Pelser, P.B. 2015: Senecio esperensis (Asteraceae: Senecioneae) - a new combination for the L'Esperance Rock groundsel, Kermadec Islands. 53(3): 131–138.
de Lange, P.J.; Norton, D.A.; Courtney, S.P.; Heenan, P.B.; Barkla, J.W.; Cameron, E.K.; Hitchmough, R.; Townsend, A.J. 2009: Threatened and uncommon plants of New Zealand (2008 revision). New Zealand Journal of Botany 47: 61–96. [as Senecio lautus var. esperensis Sykes] [Nationally Critical]
de Lange, P.J.; Norton, D.A.; Heenan, P.B.; Courtney, S.P.; Molloy, B.P.J.; Ogle, C.C.; Rance, B.D. 2004: Threatened and uncommon plants of New Zealand. New Zealand Journal of Botany 42(1): 45–76. [as Senecio lautus var. esperensis Sykes]
de Lange, P.J.; Rolfe, J.R.; Barkla J.W.; Courtney, S.P.; Champion, P.D.; Perrie, L.R.; Beadel, S.N.; Ford, K.A.; Breitwieser, I.; Schönberger, I.; Hindmarsh-Walls, R.; Heenan, P.B.; Ladley, K. 2018: Conservation status of New Zealand indigenous vascular plants, 2017. New Zealand Threat Classification Series. No. 22. [Nationally Critical]
de Lange, P.J.; Rolfe, J.R.; Champion, P.D.; Courtney, S.P.; Heenan, P.B.; Barkla, J.W.; Cameron, E.K.; Norton, D.A.; Hitchmough, R.A. 2013: Conservation status of New Zealand indigenous vascular plants, 2012. New Zealand Threat Classification Series 3. Department of Conservation, Wellington. [as Senecio lautus subsp. esperensis (Sykes) de Lange] [Nationally Critical]
Sykes, W.R. 1971: Senecio lautus in the Kermadec Islands. New Zealand Journal of Botany 9: 533–538.