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1 Phyllaries evidently spine-tipped. |
..2 Leaf bases not decurrent on the stem, the stem merely angled; pappus absent; corollas pink-purple. |
....3 Central spines of the principal phyllaries 10-25 mm long |
....3 Central spines of the principal phyllaries 1-3 mm long |
..2 Leaf bases decurrent on the stem as wings (only shortly so in C. benedicta); pappus present in at least the central flowers in the head; corollas yellow. |
......4 Heads sessile, closely subtended and partially concealed by large foliar bracts |
......4 Heads obviously pedunculate, lacking large foliar bracts subtending the head. |
........5 Larger spines of the middle and outer phyllaries 5-9 mm long; marginal and central flowers of the head with pappus |
........5 Larger spines of the middle and outer phyllaries 11-22 mm long; marginal flowers of the head lacking pappus |
1 Phyllaries not spine-tipped. |
..........6 Plant an annual; flowers pale to medium blue, flowering Apr-Jun |
..........6 Plant a perennial; flowers pink to purple, flowering Jun-Oct. |
............ 7 Phyllary appendages tapering to long, often recurved, pectinately dissected, filiform tips |
............ 7 Phyllary appendages obtuse to acute, erect or ascending. |
............ ..8 Involucres 10-13 mm high |
............ ..8 Involucres 15-25 mm high. |
............ ....9 Phyllary appendages evidently decurrent along phyllary margins |
............ ....9 Phyllary appendages not or only slightly decurrent along phyllary margins. |
............ ......10 Phyllary appendages roundish (seldom triangular), scarious, light to dark brown, undivided to irregularly lacerate |
............ ......10 Phyllary appendages more-or-less triangular, brown to black, more-or-less wholly pectinate-margined. |
............ ........11 Heads discoid (the peripheral florets not expanded and showy); pappus blackish, < 1 mm long; green parts of phyllaries nearly or completely covered by black appendages, the involucres thus appearing totally black |
............ ........11 Heads radiate (the peripheral florets expanded and showy); pappus absent or rudimentary (when present usually not black); green part of phyllaries sometimes evident, or the appendages light to dark brown. |
............ ..........12 Heads relatively broad, the pressed involucres usually as wide as or wider than long; green parts of phyllaries usually covered by brown, variously pectinate fimbriate appendages, the involucres thus light to dark brown |
............ ..........12 Heads relatively narrow, the pressed involucres usually longer then wide; green parts of phyllaries not fully covered by black appendages, the involucres black and green |