Perennial, biennial or annual, spinose or un–armed herbs or shrubs, rarely small trees. Leaves alternate, or sometimes in basal rosettes, entire or dentate to pinnatiscect-lobed, spinescent or spinulose or unarmed. Capitula one to many-flowered, solitary on scapes or corymbose or when 1-flowered aggregated into compound capitula-like synflorescence or heads, discoid, disciform or radiant, homo– or heterogamous with patent outermost florets. Involucre diversely shaped, usually of many series of bracts. Phyllaries spiny or not, leafy or membranous, apically usually drawn out into a membranous, fimbriate, lacerate or pectinate, spiny or unarmed appendages. Receptacle flat or convex, more often setose or paleate, rarely naked, rarely areolate to foveolate with fringed or scaly pit margins. Florets red, pink, purple, violet or blue, sometimes yellow or orange, usually tubular, rarely outermost row ligulate, all fertile or peripheral sterile through abortion and radiant. Corolla frequently almost actinomorphic, rarely ± zygomorphic, differentiated into lower tubular part and upper campanulate, straight or s-shaped, shallowly to deeply 5-lobed limb, outer florets elongated and radiating in Centaureinae or rarely ligulate in some genera (Atractylis). Staminal filaments glabrous, papillate or hairy, free or rarely connate into a tube; anthers sagittate, apically prolonged into a lignified, rigid, lanceolate appendage, basal appendages caudate, tails entire or fringed, rarely very short. Style usually papillate thickened below the dorsally papillose-pilose stigmatic branches, with a nectary at the base. Cypselas variable in shape, size and structure, oblong to obovoid-conical, angular or laterally weekly to strongly compressed, pale yellowish brown or mostly dark brown to blackish streaked or spotted, or entirely brown-blackish, with soft, parenchymatous or radially lignified pericarp, densely to sparsely soft hirsute or glabrous, mostly with a distinct apical rim, insertion areole basal, basal-lateral or lateral, with or without elaiosome; apically carunculate or not, Pappus of scales or bristles, uniseriate, biseriate, multiseriate, scabrid or plumose, free or connate into a ring connected to apical plate, rarely pappus absent.
A medium-sized tribe containing approximately 2360 species, in ca 75 genera, distributed in Europe, North Africa, Middle East, Central Asia, Indo-Pakistan subcontinent, China, rare in SE Asia, Australia, North and South America Represented in Pakistan by 38 genera and about 160 species.
Acknowledgements: We are thankful to the Directors and Curators of the following herbaria for providing herbarium and library facilities: A, B, DMHN, BM, E, GZU, HU, ISL, K, KUH, KAS, M, MICH, MSB, NY, O, RAW and W. The financial support of Pakistan Academy of Sciences (PAS) for the publication of this volume is gratefully acknowledged. It is a matter of pleasure to express our gratitude to Dr. Shahina A. Ghazanfar and Mr. John R. Edmondson (KEW) for critically reading the manuscript and offering valuable suggestions. Thanks are also due to late Prof. Dr. M. Ajmal Khan, Vice-Chancellor, University of Karachi and Prof. Dr. Anjum Perveen, Director, Centre of Plant Conservation for providing working facilities for the completion of this monumental work.