Asteraceae (=Compositae)

"Sunflower Family"



Flower Characteristics Representatives
Vegetative Characteristics Images
Other Points of Interest Links


Flower Characteristics
  • inflorescence or few to many flowers borne in a head (=capitulum)
  • individual flowers are often called "florets" and are of 2 types:
  • 1)  disc flowers
    • regular and epigynous
    • no sepals as we know them, but a calyx of fluffy bristles called a pappus
    • tubular corolla of 5 lobes
    • stamens 5, epipetalous with the anthers connate
    • pistil with  inferior ovary of 2 carpels, but ovules reduced to 1, 1 locule, stigma branched and curved
    • floral formula: Asteraceae floral formula -achene
  • 2)  ray flowers
    • identical to disc flowers except the tubular corolla is expanded on one side into a long petal lobe making the flower irregular
    • floral formula: Asteraceae floral formula -achene (but frequently sterile in radiate heads)
  • heads of three types:
    • 1) discoid heads: only disc flowers (e.g. Antennaria)
    • 2) ligulate heads: only ray flowers (e.g. Taraxacum, Cichorium, Lactuca)
    • 3) radiate heads: both ray and disc flowers (e.g. Senecio, Helianthus)
Vegetative Characteristics
  • mostly herbs, a few shrubs (and a few tropical trees)
  • leaves simple or comound; margins entire, toothed, lobed, etc.; alternate but in some opposite or even whorled 
Other Points of Interest
  • the largest dicot family with 950 genera and 20,000 species
  • distributed all over the earth and in almost all habitats
  • food plants include lettuce, globe artichoke, endive, salsify, and chicory
  • pollen of ragweed (Ambrosia)causes allergic reaction in some humans
  • many weeds
  • many used as ornamentals: strawflower, shasta daisy, english daisy, marigolds, zinnia
  • Sunflower (Helianthus)
  • Goldenrod (Solidago)
  • Lettuce (Lactuca)
  • Aster  (Aster)
  • Ragweed (Ambrosia)
  • Marigold (Tagetes)
  • Blue Mink (Ageratum) 



Amaryllidaceae Cruciferae Lamiaceae Rosaceae
Apiaceae Cyperaceae Leguminosae Scrophulariaceae
Araceae Fabaceae Liliaceae Solanaceae
Asteraceae Fagaceae Magnoliaceae Umbelliferae
Brassicaceae Gramineae Orchidaceae Violaceae
Caryophyllaceae Iridaceae Poaceae  
Compositae Labiatae Ranunculaceae