Asteraceae
Asteraceae Bercht. & J.Presl (alternative conserved name Compositae), is the largest family of flowering plants, comprising approximately 1,900 genera and 32,000–33,000 species distributed worldwide. Molecular phylogenetic studies have substantially refined tribal and subfamilial relationships, recognizing more than 40 tribes within the family. Despite these revisions, Asteraceae remains a well-supported monophyletic group characterized by its unique capitulum (flower head) and specialized fruit morphology.
Key characteristics
- Herbs, shrubs, or rarely trees
- Inflorescence a capitulum (flower head) surrounded by involucral bracts
- Ray and/or disc florets present
- Stamens five with syngenesious anthers
- Inferior ovary
- Fruit a cypsela, commonly with a pappus
Distribution
Asteraceae has an almost cosmopolitan distribution, occurring on every continent except Antarctica. It reaches its greatest diversity in temperate, Mediterranean, montane, and semi-arid regions of South America, North America, Africa, Central Asia, and the Mediterranean Basin. Members occupy virtually every terrestrial habitat, including grasslands, deserts, alpine meadows, forests, wetlands, coastal dunes, disturbed sites, and agricultural landscapes. Many species are ecological pioneers and dominate secondary vegetation. Asteraceae is one of the most diverse flowering plant families in Pakistan and occurs throughout. Species inhabit alpine meadows, temperate forests, deserts, dry scrublands, riverbanks, cultivated fields, wetlands, and saline habitats. The family is particularly abundant in the Himalaya, Karakoram, Hindu Kush, Salt Range, Potohar Plateau, and uplands, where numerous endemic and medicinal taxa occur.