Centaurea amadanensis Schultz Bipontinus (1847: 326)

Negaresh, Kazem & Rahiminejad, Mohammad Reza, 2018, A revision of Centaurea sect. Cynaroides (Asteraceae, Cardueae-Centaureinae), Phytotaxa 363 (1), pp. 448-450 : 448-450

3. Centaurea amadanensis Schultz Bipontinus (1847: 326)

Amberboa decurrens Candolle (1838: 560) . Phaeopappus decurrens (DC.) Boissier (1875: 600) . Tomanthea decurrens (DC.) Takhtajan (1939: 243) . Paraphysis decurrens (DC.) Dostál (1973: 76) . Type:— IRAN. Prov. Hamedan: Hamedan, 1837, Aucher-Eloy 3196 (lectotype G! designated here by Negaresh, isolectotypes G!, K!, P!: two sheets).

Biennial plants, with thick and napiform root, whole plant usually green, 40–150(–250) cm tall; collar of fibrous petiolar remains present at stem base. Stem erect, stout, simple, sometimes branched from near base to median part, up to 30 mm diam. at base, cylindrical, with thick green or yellowish striations, purplish in lower part, lower to median parts covered with sparsely to densely hirsute-articulate hairs, up to 3 mm long, upper part in juvenile phase lanate but in mature phase glabrous. Leaves coriaceous, papyraceous (on drying), ± loosely covered with hirsute-articulate on both sides, densely along midrib and veins, with white and elevated veins on both sides. Basal and lower cauline leaves large, basal ones usually withered at anthesis, with a long petiole, hastate or broadly ovate, broadly triangular, ovate-triangular or cordate-ovate, sometimes lyrate; terminal segments much larger, 13–20 × (8–) 12–15 cm, obtuse to subacute at apex; lateral segments smaller, 1–2 pairs, lanceolate; sometimes lower ones with auricles at base, or broadly decurrent along petiole. Median cauline leaves sessile, simple, broadly lanceolate, oblong to oblong-subpandurate, (8–)10–14(–18) × 2–4 cm, broadly decurrent, up to 50 mm along stem, or winged, obtuse or acute at apex. Upper cauline leaves increasingly smaller, sessile, simple, lanceolate, oblong-lanceolate to linear, 2–12 × 0.2–2 cm, narrowly decurrent, sometimes not decurrent, acute or acuminate at apex. Capitula numerous, variable in number, (2–)5 to 15(–50), usually arranged in a raceme but sometimes in raceme-dichasium, or upper capitula arranged in raceme and lowest ones arranged in dichasium, upper capitula sessile or shortly pedunculate, gradually longer towards base, up to 20(–30) cm long, lowest sometimes with 2–5 heads. Involucres ovoid or obconical, 25–35(–40) × 22–30(–35) mm. Phyllaries multiseriate, coriaceous, imbricate, green in vivo, yellow-brownish in sicco, densely floccose-tomentose hairs, acute at apex or with a short mucro (0.5–3 mm long, “subsp. gymnoclada ”), or with spiniform appendages (spine up to 20 mm long), rarely fringed in upper part, with 1–2 pairs short fringes ( “subsp. amadanensis ”), sometimes with denticulate appendages ( “subsp. ranjbarii ”). Flowers white in vivo, sulphur in sicco, rarely pink; central florets hermaphroditic, 38–40 mm long, corolla 15–16 mm long, 5-lobed, lobes 7–8 mm long, anther tube pink, style equal with corolla, stigma exserted part from corolla; peripheral florets sterile, finely dissected, shorter than central ones, very few (1–3 in each capitulum), very inconspicuous, not radiant, 3-lobed, limb lobes linear. Achenes oblong, 6–8 mm long, 3–4 mm wide, whitish or straw-coloured, smooth and shiny, glabrous; insertion areole lateral, 0.8–1 mm long. Pappus persistent, multiseriate, scabrous, whitish or pale brown, sometimes pink or pale purple, 10–15 mm long, bristles of inner rows slightly longer than others.

Taxonomic and distribution remarks: — Centaurea amadanensis is widely distributed in Ilam, Lurestan, Kermanshah, Kurdistan, Markazi and Hamedan Provinces, from SW to W Iran ( Fig. 5 ). Also, there are few populations in near central part of Iran (Isfahan Province) and Sulaymaniyah Province, NE Iraq ( Fig. 5 ). It is an Irano-Turanian element, and grows on rocky slopes, stony slopes, roadsides, fallow fields, among scattered shrubs, margin of Quercus forest, meadow-steppe slopes and mid-montane zones, at elevations of 700–2200 m ( Figs. 3E, 3F , 7 and 11 ). Centaurea amadanensis with C. karamianiae , C. mozaffarianii and C. nemecii forms a natural species group within C. sect. Cynaroides which is well known by morphological characters such as: peripheral florets very inconspicuous, very few (1–3(–5) in each capitulum), and shorter than central florets. It seems that these characters are important and can be used in phylogentic studies. In this group, C. amadanensis and C. mozaffarianii have a pink anther tube, whereas C. karamianiae and C. nemecii have a white anther tube. However, C. amadanensis is more widely distributed than others.

In Flora Iranica, Wagenitz (1980) recognized two varieties in C. amadanensis based solely on the length of spine: var. amadanensis and var. gymnoclada . But, he failed to pay attention to the geographical distribution of these varieties. Our field observations showed that there is a clear geographical delimition between these two varieties and they were not found together in the field. In view of the considerable stability of spine length in C. amadanensis , and also because of the geographical or ecological differentiation, we suggest a new taxonomical assignment. In addition, we described a new peculiar subspecies, i.e. subsp. ranjbarii , because it has pink flowers and denticulate appendages which are an exception in the C. amadanensis complex ( Fig. 12 ). So, C. amadanensis can be treated as including three subspecies.

Figures

FIGURE 3. Different habitats on the Centaurea sect. Cynaroides. A. C. imperialis. B. C. regia. C. C. nemecii. D. C. alfonsoi. E and F. C. amadanensis.

FIGURE 5. Distribution of Centaurea amadanensis subsp. amadanensis (circles), C. amadanensis subsp. gymnoclada (squares), and C. amadanensis subsp. ranjbarii (triangles).

FIGURE 7. Centaurea amadanensis Schultz Bipontinus subsp. amadanensis (Ranjbar & Negaresh 29623, BASU). A. inflorescence. B. close up of capitule. C and D. habit and habitat. Scale A = 3 cm, B = 1 cm, C and D = 6 cm.

FIGURE 11. Centaurea amadanensis Schultz Bipontinus subsp. gymnoclada (Jaub. & Spach) Negaresh (Ranjbar & Negaresh 30545, BASU). A. capitula. B. inflorescence. C. habit and habitat. D. leaves. Scale A = 1 cm, B = 3 cm, C = 10 cm, D = 6 cm.

FIGURE 12. Centaurea amadanensis Schultz Bipontinus subsp. ranjbarii Negaresh (Negaresh & Ranjbar 33186, BASU). A. habit. B. close up of capitule. C. leaves. Scale A and C = 5 cm, B = 1 cm.