Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
White Heath Aster
Aster pilosus Willd.
- Family: Composite (Compositae)
- Flowering: August-October
- Field Marks: This aster is recognized by its numerous white flower heads subtended by
slender-pointed, green-tipped bracts and by its subulate-tipped leaves.
- Habitat: Wet or dry open areas, roadsides.
- Habit: Perennial herb from a thickened rootstock.
- Stems: Upright, branched, up to 5 feet tall, smooth or with spreading hairs.
- Leaves: Alternate, simple, oblanceolate to linear, sometimes slightly toothed, at least the uppermost subulate-tipped, otherwise merely pointed, tapering to the base, up to 4 inches long, the lower on long stalks, the upper without stalks.
- Flowers: Many crowded into heads, the heads 1/4-1/3 inch high, arranged in a much branched panicle often more than one-half the height of the plant, each head subtended by several slender-pointed, green-tipped, inrolled, appressed bracts, some of the flowers forming white rays, others forming a central yellow disk; ray flowers 16-35, white, 1/4-1/2 inch long; disk flowers 20-40, tubular.
- Sepals: 0.
- Petals: Some united to form flat white rays, others united to form tubular yellow disk flowers.
- Stamens: 5.
- Pistils: Ovary inferior, sparsely hairy.
- Fruits: Achenes ellipsoid, sparsely hairy, about 1/8 inch long, subtended by white hairs.
- Notes: Gleason and Cronquist use Asteraceae for this family. The ray flowers are sometimes purplish.
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