Centaurea sect. Phaeopappus (DC.) Hoffmann, 1895

Ranjbar, Massoud & Negaresh, Kazem, 2013, A revision of Centaurea sect. Phaeopappus (Asteraceae, Cardueae), Phytotaxa 123 (1), pp. 1-40 : 3

Key to the species of Centaurea sect. Phaeopappus

1 Capitula arranged in a raceme; involucres <15 mm wide; appendages entire or irregularly denticulate C. stapfiana

– Capitula solitary; involucres> 15 mm wide; appendages ciliate ............................................................................... 2

2 Appendages never decurrent ....................................................................................................................................... 3

– Appendages sometimes shortly decurrent on crenate margins ................................................................................... 9

3 Median and upper cauline leaves broadly decurrent .................................................................................................. 4

– Median and upper cauline leaves not decurrent .......................................................................................................... 7

4 Flowers purple ............................................................................................................................................ C. handelii

– Flowers yellow or white .............................................................................................................................................. 5

5 Median and upper cauline leaves obtuse at apex; upper cauline leaves slightly longer than capitula; involucres ca. 20 mm long .................................................................................................................................................. C. obtusifolia

– Median and upper cauline leaves acute or acuminate at apex; upper cauline leaves almost shorter than capitula; involucres (25–) 30–40 mm long ........................................................................................................................................ 6

6 Plant glabrous; basal and lower leaves undivided; spine 3–7 mm long; achenes brown or dark brown and 6–8 mm long; pappus straw-coloured to brownish, 10–14 mm long ..................................................................... C. albonitens

– Plant loosely floccose-tomentose; basal and lower leaves lyrate; spine 5–12 mm long; achenes deep purple and 10– 11 mm long; pappus deep violet, 5–7 mm long ....................................................................................... C. heratensis

7 Plant 10–25 cm tall; stem erect to ascending or suberect; basal and lower leaves 10–12 cm long; synflorescence 3–4- cephalous; cilia ca. 1 mm long ............................................................................................................... C. microlopha

– Plant 30–70(–80) cm tall; stem erect; basal and lower leaves (22–) 26–40 cm long; synflorescence 1(–2)-cephalous; cilia 3–5 mm long ....................................................................................................................................................... 8

8 Plant arachnoid-canescent; all leaves undivided; cauline leaves broadly lanceolate to elliptic, obtuse to subacute at apex; appendages straw-coloured to light brown ....................................................................................... C. hellwigii

– Plant tomentose-canescent; basal and lower leaves divided; cauline leaves lanceolate or oblong, short acuminate or mucronate at apex; appendages blackish-brown ..................................................................................... C. spectabilis

9 Involucres subglobose, 25–35 mm wide ............................................................................................... C. farsistanica

– Involucres oblong or ovoid, (17–) 20–25 mm wide .................................................................................................. 10

10 Flowers purple or dark wine-red ............................................................................................................................... 11

– Flowers yellow .......................................................................................................................................................... 12

11 Involucres 20–23 mm long; cilia 5–9 on each side; spine 3–5 mm long, brownish or whitish .................... C. assadii

– Involucres 27–32 mm long; cilia 7–15 on each side; spine (3–) 4–8 mm long, dark brown to blackish ....................... ............................................................................................................................................................ C. daralagoezica

12 Terminal spine 4–11 mm long; appendages concealing a major part of phyllaries; leaves almost pinnatisect or pinnatipartite .................................................................................................................................................. C. phaeopappa

– Terminal spine 2–5 mm long; appendages only partly concealing the basal part of phyllaries; leaves often simple or with few divisions ..................................................................................................................................................... 13

13 Stem erect; basal leaves shorter than stem; upper cauline leaves shorter than capitula; pappus 13–16 mm long ........ .................................................................................................................................................................. C. indistincta

– Stem arcuate-ascending or suberect, sometimes strongly abbreviated; basal leaves almost longer than stem; upper cauline leaves longer than capitula; pappus ca. 22–24 mm long ................................................................. C. aucheri