Senecio macedonicus Grisebach (1846: 221)

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

12. Senecio macedonicus Grisebach (1846: 221) . TYPE: Greece, Macedonia, E . Frivaldszky s.n. (lectotype, designated by Strid (2000: 274), G-150321 image!; isolectotypes, GOET-2380 image!, K!, LE!, MO-5578157!, WU!) .

SYSTEMATICS OF SENECIO SECTION CROCISERIS

Phytotaxa 211 (1) © 2015 Magnolia Press • 49 Perennial herb. Rhizome 3.2–6.5 cm long, 0.7–1 cm in diam., ± horizontal, with swelled fastigiate roots. Stem 43–116 cm, erect, leaved, corrugated, solid, not ramificated, glabrescent to slightly arachnoid, base without remnants of old leaves or tufts of hairs. Basal leaves 9–21 cm long, 2.9–6.6 cm wide, persistent, sometimes withering early, lanceolate to broadly lanceolate (ratio basal leaf width / basal leaf length = 0.17–0.53), obtuse, sometimes acute, attenuate to cuneate, with a petiole 5–19 cm long, entire to crenate, sometimes slightly dentate, rarely irregularly pinnatipartite (lobes up to 25 mm deep), glabrescent to weakly arachnoid, concolorous. Cauline leaves 6–16; middle cauline leaves 7.2–18 cm long, 1.2–4.2 cm wide, alternate, lanceolate to broadly lanceolate (ratio middle leaf width / middle leaf length = 0.12–0.43), acute, rarely obtuse, sessile, sometimes attenuated into a petiole up to 8 cm long, entire to slightly dentate, rarely irregularly pinnatipartite (lobes 9–21 mm deep), glabrescent to weakly arachnoid, tertiary venation inconspicuous; upper cauline leaves 2–7 cm long, 0.6–2.8 cm wide, ovate to broadly lanceolate (ratio upper leaf width / upper leaf length = 0.17–0.52), acute, sessile, rarely with a short petiole, entire to subentire, rarely pinnatipartite, glabrescent to arachnoid-tufted near margin. Synflorescence 3.5–23 cm long, corymbose, with ovate-lanceolate bracts similar to upper leaves. Capitula (2–)5–9(–16), 27.6–45 mm in diam.; involucre 11.4–19.6 mm in diam., 8–13 mm long, bell-shaped; involucral bracts (20–)21–23(–24), 7.1–11.6 mm long, 1.4–2.2 mm wide, with scarious margin 0.4–0.7 mm wide, ensiform to subulate, attenuate, 0–2-keeled, apex often with a black spot, glabrescent to weakly arachnoid; supplementary bracts (8–)10–13(–17), 4.6–10.3 mm long, 0.6–2.1 mm wide, lanceolate to broadly lanceolate, rarely linear-oblong, sometimes with scarious margin up to 0.4 mm, a third to two thirds as long as involucral bracts, arachnoid to glabrescent, often slightly imbricated. Ligulate florets 11–21, 15.5–22.2 mm long, yellow; tubular florets 7.0– 10.3 mm long, 0.7–1.4 mm in diam., yellow. Achenes ca. 3.8 mm long, ca. 0.8 mm wide, subcylindrical, shorter than pappus, with ca. 10 ribs, with dense trichomes covering ± the whole surface 0.3–0.4 mm long; pappus 5.9–9.5 mm long, whitish.

Etymology: — The epithet macedonicus refers to the ancient Kingdom of Macedonia, the geographical area where Frivaldszky von Frivald collected the original material.

Discussion: — Senecio macedonicus is a robust plant characterized by bearing ovate-lanceolate synflorescence bracts, similar to the upper leaves, and supplementary bracts of the involucre lanceolate to linear-oblong, sometimes with scarious margin. It is a variable species mostly with regard to the abundance of indumentum, and the shape of leaves. It has to be noted that the septentrional populations tend to be less pubescent than the meridional ones, which are considered here within the intraspecific variability. Regarding the variability of the leaves shape, we recognize two subspecies.

Morphologically, the closest species to S. macedonicus are S. castagneanus from western Anatolia, S. pseudoorientalis from eastern Anatolia, and S. lopezii from southern Iberian Peninsula. Regarding S. castagneanus , the shape and size of the synflorescence bracts are useful characters to discriminate each other, ovate-lanceolate in S. macedonicus vs. linear-oblong to narrowly lanceolate, and usually smaller, in S. castagneanus . In the case of S. pseudoorientalis , which sometimes displays similar synflorescence bracts, the achene indumentum may be used for differentiation (glabrous in S. pseudoorientalis vs. hairy in S. macedonicus ). In addition, S. pseudoorientalis usually is less pubescent and shows smaller capitula. Regarding S. lopezii , see comments under that species.

Senecio macedonicus does not overlap with S. castagneanus . According to Matthews (1975), as S. macedonicus Ascherson misidentified the specimen Sintenis 628 of “Iter trojanum 1883”. It corresponds to S. castagneanus . On the other hand, Orphanides identified as S. tmoleus (synonym of S. castagneanus ) one specimen that we ascribe to S. macedonicus . It is number 109 of “Flora Graeca 1852” from Ziria mountains (Mount Kyllini-Peloponnese). Likewise, Boissier and Heldreich distributed a Heldreich collection, dated July 1844, from the “regione superiori Taygeti” (Peloponnese), under the “herbarium” name Senecio tmoleus var. longifolius . Oddly, Boissier later included this name in the synonymy of S. macedonicus .

Halácsy (1904: 484) described S. longipedunculatus from Mount Parnassus (Delphi, Greece), characterized by its capitula born on long pedicels (up to 20 cm), involucre 8–9.5 × 10–12.9 mm, glabrescent, and linear-oblong supplementary bracts. In addition, its cauline leaves decrease strongly in size as they progress up the stems. According to Kadereit (1991), it may be related to S. macedonicus since they grow in the same region, but the synflorescence bracts are not foliose and the upper cauline leaves are not well-developed as S. macedonicus has. Also, the supplementary bracts of the involucre are linear-oblong, in no case lanceolate or broadly lanceolate. These characters also might bring this taxon close to S. castagneanus . Unfortunately, S. longipedunculatus is only known from the original material with immature achenes that lack an essential character to compare it with S.

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castagneanus . Consequently, we prefer to include S. longipedunculatus under “Doubtful or excluded names”. More collections and further investigation is needed to elucidate its taxonomic position.