Senecio trapezuntinus Boissier (1875: 393)

Calvo, Joel, Álvarez, Inés & Aedo, Carlos, 2015, Systematics of Senecio section Crociseris (Compositae, Senecioneae), Phytotaxa 211 (1), pp. 448-450 : 448-450

24. Senecio trapezuntinus Boissier (1875: 393) . TYPE: Turkey, Trabzon, Trebizonde , [40º59'N 39º43'E], 27 Apri 1862, E. Bourgeau 127 (lectotype, designated here, G-150294 image!; isolectotypes, G-308018!, GOET-2420 image!, GOET-2421 image!, P-743133 image!, P-743134 image!, P-743135 image!, P-743136 image!, P-4115044 image!, P-4307008 image!, P-4307034 image!).

Perennial herb. Rhizome ca. 6 cm long, ca. 0.9 cm in diam., ± horizontal, with swelled fastigiate roots. Stem 68–77 cm, erect, leaved, corrugated, solid, not ramificated, glabrous, base without remnants of old leaves or tufts of hairs. Basal leaves 9–12.5 cm long, 6.5–8.2 cm wide, persistent, ovate (ratio basal leaf width / basal leaf length = 0.66–0.72), obtuse, cordate, with a petiole 8–17 cm long, dentate, sometimes irregularly dentate or crenate (teeth 2–7 mm deep), glabrous, concolorous. Cauline leaves 4–5; middle cauline leaves 9–10.4 cm long, 6.4–7 cm wide, alternate, lyrate to ovate (ratio middle leaf width / middle leaf length = 0.62–0.78), obtuse, sometimes acute, amplexicaul-auriculate to cordate-truncate with a petiole up to 13 cm long, dentate, sometimes irregularly dentate (teeth 3–4 mm deep), glabrous, tertiary venation conspicuous; upper cauline leaves 6.5–13 cm long, 2.9–6 cm wide (ratio upper leaf width / upper leaf length = 0.45–0.46), acute, amplexicaul, dentate (teeth 2–8 mm deep), glabrous. Synflorescence ca. 32 cm long, corymbose, with linear-lanceolate bracts, pinnatifid to entire. Capitula 10–17, 35–45 mm in diam.; involucre 15–16 mm in diam., 7–9 mm long, cupuliform; involucral bracts 21–23, 6.1–6.9 mm long, 1.2–1.6 mm wide, with scarious margin 0.3–0.4 mm wide, ensiform, acute, 0–2-keeled, apex usually with a black spot, glabrous; supplementary bracts 14–16, 2.9–3.9 mm long, 0.4–0.6 mm wide, subulate, without scarious margin, a third to a half as long as involucral bracts, rarely longer, weakly arachnoid, not imbricated. Ligulate florets 10–13, 17–22 mm long, yellow; tubular florets 8.2–8.5 mm long, 0.8–1 mm in diam., yellow. Achenes 4–4.4 mm long, 0.8–1 mm wide, subcylindrical (ratio achene width / achene length = 0.19–0.23), shorter than pappus (ratio achene length / pappus length = 0.65), with 10–11 ribs, with dense intercostal trichomes 0.1–0.2 mm long; pappus ca. 6.6 mm long, whitish. Chromosome number: 2 n =40 ( Altınordu et al. 2014: 2208). Figure 30 .

Distribution and habitat: — Turkey (endemic of Trabzon Province); rocky places; elevation of ca. 200 m ( Figure 28 ).

78 • Phytotaxa 211 (1) © 2015 Magnolia Press

CALVO ET AL.

Phenology: — Flowering from April to May.

Etymology: — The epithet trapezuntinus refers to Trapezund (also historically known as Trebizond, Tribisonde, and Trapezus), officially Trabzon. It is a town on the Black Sea coast of northeastern Turkey and the capital of Trabzon Province.

Discussion: — Senecio trapezuntinus is distinctive by its ovate, cordate basal leaves, glabrous and with a conspicuous tertiary venation, and the cauline leaves lyrate to ovate, usually amplexicaul-auriculate. More collections should be studied to better understand the variability of this species, such as in the capitula number.

The species is slightly similar to S. perralderianus from northwestern Maghreb (see comments under it), and S. olgae from Central Asia. Senecio trapezuntinus differs from the latter mainly in the shape of the basal leaves (ovate vs. deltate to lyrate, sometimes broadly ovate in S. olgae ), and in the number of supplementary bracts (14–16 in S. trapezuntinus vs. (3–)4–6(–8) in S. olgae ).

The collector numbers of the lectotype and the isolectotypes do not match. Probably the number written on the lectotype label (n.º 360) corresponds to a field number, while the number on the isolectotypes (n.º 127) corresponds to the number of “Plantae Armeniacae 1862” collected by Bourgeau. Moreover, Boissier wrongly recorded Balansa as the collector of the type material, instead of Bourgeau.

Selected specimens examined. TURKEY. Trabzon: Boztepe , 40º59’N, 39º43’E, 21 IV 2006, Ü . Budak , E . Hamzaoğlu & A . Aksoy 2006 ( MA) .

Figures

FIGURE 28. Distribution map for Senecio racemosus (Bieberstein) Candolle subsp. racemosus (▲), S. buschianus Sosnowsky (○), and S. trapezuntinus Boissier (●).

FIGURE 30. A–J. Senecio perralderianus Cosson—a. Habit (drawn from Dubuis 9769, MA).—b. Habit (drawn from Podlech 39203, G).—c. Capitulum (drawn from Dubuis 9769, MA).—d. Involucral bract (drawn from Dubuis 9769, MA).—e. Supplementary bract (drawn from Dubuis 9769, MA).—f. Ligulate floret (drawn from Podlech 39203, G).—g. Tubular floret (drawn from Podlech 39203, G).—h. Stamens (drawn from Podlech 39203, G).—i. Achene (drawn from Dubuis 9768, MA).—j. Indumentum of achene (drawn from Dubuis 9768, MA). K–P. Senecio trapezuntinus Boissier—k. Lamina of basal leave (drawn from Bourgeau 127, G).—l. Capitulum (drawn from Budak 2006, MA).—m. Involucral bract (drawn from Budak 2006, MA).—n. Supplementary bract (drawn from Budak 2006, MA).—o. Achene (drawn from Budak 2006, MA).—p. Indumentum of achene (drawn from Budak 2006, MA).