Centaurea stevenii Marschall von Bieberstein (1808: 356)

Negaresh, Kazem, Rahiminejad, Mohammad Reza & Ranjbar, Massoud, 2014, A taxonomic study on Centaurea sect. Rhizocalathium and C. sect. Pseudoseridia (Asteraceae, Cardueae-Centaureinae) in Iran, Phytotaxa 174 (1), pp. 43-60 : 56-59

Centaurea stevenii Marschall von Bieberstein (1808: 356) .

Phaeopappus stevenii (M.Bieb.) Koch (1851: 437) . Type :— GEORGIA. Steven s.n. (holotype LE).

Perennial plants with long and thick root, vertical or oblique. Stems usually decumbent (or prostrate), at end ascending, 10–40 cm tall, with few short branches, sometimes simple, grayish-green or more or less grayish, loosely covered with arachnoid hairs often mixed with articulate hairs, somewhat stiff or short hairs. Leaves petiolate (or the upper ones subsessile) with narrow base, lyrate to pinnatilobate, with 2–4 pairs of lateral segments or undivided, acute or subacute at apex, often subobtuse; terminal segments very larger, entire, lanceolate or oblanceolate; lateral segments small, oblong-elliptical or ovate-rhombic; loosely covered with arachnoid hairs often mixed with articulate hairs, and covered with sessile punctate glands. Capitula solitary, at tips of stems and lateral branches. Involucres ovoid, 15–20 × 10–15 mm, ± densely covered with arachnoid hairs. Phyllaries coriaceous, imbricate dark green or green-yellowish. Outer and median phyllaries broadly ovate; inner phyllaries oblong-lanceolate.Appendages small, coriaceous, brown or pale reddish-brown, usually reflexed, triangular, with (3–)5–7(–9) digitate spinules 2–3 mm long, almost equal, innermost membranous, unevenly toothed. Flowers yellow; central florets hermaphrodite, ca. 20 mm long, corolla with orange nerves; peripheral florets finely dissected, not radiant, 4-lobed, limb lobes linear-filiform. Achenes ovate-oblong, ovate-lanceolate, 4.5–5.0 mm long, 2.0– 2.5 mm wide, gray-brown, striate, sparsely hairy; hilum lateral, yellowish, ca. 1.5 mm long, glabrous. Pappus whitish, 1–2.5(–4) mm long, inner pappus hairs shorter. Flowering June to July.

Taxonomic and distribution remarks: — Centaurea stevenii makes a new record from Iran ( Fig. 11 ). It is occurs in the clay mountains around Bazargan of West Azerbaijan Province, at elevations of 1400–1700 m ( Fig. 3 ). The main distribution area of C. stevenii lies in E Turkey (?), Armenia and Georgia ( Fig. 3 ). The species is relatively far from the main distribution area of other species of C. sect. Pseudoseridia.

Chromosome numbers: — Centaurea stevenii is a diploid species with the chromosome number of 2 n = 2 x = 16 ( Fig. 11E , Table 1). Our results agree with the report by Poddubnaja-Arnoldi (1931) who reported the same chromosome number 2 n = 2 x = 16 for C. stevenii .

Selected specimens examined: — IRAN. Prov. West Azerbaijan: mountains around Bazargan, 1415 m, 22 May 2011, Ranjbar & Negaresh 25787 (BASU!); Bazargan, 1860 m, 24 June 2012, Ranjbar & Negaresh 32152 (BASU!); Maqoo, Ghara Ziaheddin toward Siah Cheshme, 40 km to Siah Cheshme, 1570 m, 10 July 2003, Rahiminejad & Dehghan 15247 (HUI!). GEORGIA. Prov. Tiflis, Dushet, Grossheim s.n. (B!). ARMENIA. Ani, inter stationes viae ferreae Ani et Bagravan, in declivibus stepposis lapidosis, 1500 m, 5 July 1960, Czerepanov & Tzvelev s.n. (B!).

Figures

FIGURE 3. Distribution of C. rhizantha (1), C. vanensis (2), C. lasiorhiza (3), C. ispahanica subsp. ispahanica (4), C. ispahanica subsp. sirjanensis (5), and C. stevenii (6).

FIGURE 11. Centaurea stevenii (Ranjbar & Negaresh 32152, BASU). A. close up of capitulum (focused on digitate spinules). B. close up of capitulum (focused on flowers). C. close up of achene with pappus. D. habit and habitat. E. metaphase plate (2n = 16). Scale A and B = 5 mm, C = 1 mm, D = 3 cm.