- Flowers: Perfect or imperfect and the plants then usually monoecious; two kinds of flowers:
- DISK - actinomorphic, tubular corolla
- RAY - zygomorphic, ligulate corolla
- Calyx = pappus, bracts = chaff
Stamens with free filaments attached to base of corolla, but anthers connate into a tube around style
Carpels 2, syncarpous; ovary inferior, 1-locular with 1 basal ovule
Inflorescences: Heads surrounded by phyllaries; heads arranged in secondary cymes or racemes
Fruits: Achenes
Habit: Mostly annual, biennial, or perennial herbs; shrubs or tree-like at high elevations in the tropics and on some islands
Leaves: Alternate, opposite, or whorled, mostly simple, often lobed or divided, rarely compound
A BIG family, most advanced dicot family
Divided into 13 tribes (you are NOT expected to know these tribes!)
Examples:
3 basic types of heads:
- both disk & ray flowers present
- Aster
- Bidens (beggar-ticks)
- Chrysanthemum
- Echinacea, Ratibida, Rudbeckia (coneflowers)
- Helianthus (sunflowers)
- Senecio (ragworts)
- Solidago (goldenrods)
- Tagetes (marigolds)
- Zinnia
- disk flowers only
- Arctium (burdock)
- Cirsium and Carduus (thistles)
- Cynara scolymus (artichoke)
- Eupatorium (Joe-Pye weed)
- Liatris (blazing stars)
- Vernonia (ironweeds)
- ray flowers only (sap often milky)
- Cichorium (chicory, endive)
- Hieracium (hawkweed)
- Krigia (dwarf dandelion)
- Lactuca (lettuce)
- Taraxacum (dandelion)
- Tragopogon (goat's-beard)
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