Asteraceae

Defining Characteristics

• Composite flower heads (capitula) — what appears to be one flower is actually many florets on a receptacle
• Ray florets (ligulate, often sterile) surrounding central disk florets (tubular, bisexual)
• Involucre of bracts (phyllaries) beneath the capitulum
• Inferior ovary producing a single-seeded cypsela (achene-like) fruit
• Pappus of hairs, scales, or awns atop the cypsela, often aiding wind dispersal
• Anthers fused into a tube around the style (syngenesious stamens)

Notable Genera

• Helianthus (sunflower)
• Bellis / Leucanthemum (daisy)
• Taraxacum (dandelion)
• Aster / Symphyotrichum (aster)
• Solidago (goldenrod)
• Artemisia (wormwood, sagebrush)
• Lactuca (lettuce)
• Chrysanthemum (chrysanthemum)

Notes

Largest family of flowering plants by species count. Economically important for food (lettuce, sunflower oil, artichoke), medicine (Echinacea, chamomile), and horticulture. Ecologically significant as major pollinator resources across most terrestrial biomes.