Flower, Fruit, Foliage and Form
Flower:
- Head of many (composite) small sessile (not stalked) flowers (florets)
- Florets perfect
- Aggregated (clustered) on common receptacle
- Surrounded by involucral bracts
- Outermost florets mature first, center ones last ( indeterminate )
- Ray florets:
- Corolla tubular only at base; expanded upward into prominent ligule
- No stamens, floret is functionally pistillate
- Disk florets:
- Regular, tubular corolla
- Usually normal and perfect
- Ligule florets:
- Corolla expanded to one side in a ligule
- Flower heads composed only of ligulate florets are ligulate heads
- Flower heads composed only disk florets are discoid heads
- Flower heads composed only disk florets in center and ray florets around margin are radiate heads
- Heads are single or in a panicle or corymb
| radiate head | ligulate head | discoid head |
Th Asteraceae Flowers animation will help to depict the different flowers that compose the inflorescences of the plants in the Asteraceae family. After viewing this animation, you should have a better understanding of the differences between ligulate, discoid and ray flowers.
*no audio on the video*
Fruit:
- Achene—dry, indehiscent (not splitting open) capsule
Form:Annual, perennial, or biennial herbs and occasionally shrubs. A basal rosette is often formed at the base of the plant (daisy) but leaves may (coneflower) or may not (rudbeckia) be present on the stem.
basal rosette
coneflower (Echinacea)
Leaves:
- Type: simple, rarely compound
- Arrangement: alternate, opposite, rarely whorled. Leaves sometimes opposite below and alternate above. Exstipulate (no stipules)
- Margins: various, entire to toothed, dissected, occasionally compound
Stems:Stems maybe hollow or solid and contain a milky white sap. Stems may also be prickly or pubescent.
Roots: Roots may be found near the surface (daisy) or a deep taproot (dandelion.)